Green Building Innovation_ TU Delft

Thermal and visual comfort study Gertrudis College in Roosendaal AR3B320 - Green Building Innovation

Technical University Delft, 21 November 2012 Tutors: R.M.J. Bokel and G.J. Hordijk

Anne Cowan 1502492 Aris Gkitzias 4180380 Paressa Loussos 1373528 Martin van Meijeren 1376101

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Preface In front of you is the report of the study on the Gertrudis College in Roosendaal. As master students of Building Technology in the faculty of Architecture at the TU Delft, we chose to do the project “Green Building Innovation”. In this project the indoor comfort of a building is the main subject of study, and the Gertrudis School provided an interesting occasion due to the placement of a new sunshade system and new TV screens.

The management of the school, as well as Hunter Douglas (the company that produced the new sunshade system), were curious of the effect of these sunscreens on the indoor comfort. For the past eight weeks we have done a climate comfort study in this school, to see what effect this new sunshade had in comparison to the old sunshade of the school. The results of this study we have worked out in this report.

For us it was a great opportunity to learn more about thermal and visual comfort and making measurements, but also about performing comfort surveys and analyzing the result from these different parts.

Without the help of people from different parties, this study wouldn’t have been possible. First we would like to thank Regina Bokel and Truus Hordijk, from the department of Building Physics in the Architecture faculty, for guiding us during this comfort study and for their help to make this report.

Also we would like to thank the company Hunter Douglas for their support. Especially Wouter Beck for all the information he gave us on the new sunshade system and Sander Teunissen for his help on gaining the sunshade data.

Furthermore we would like to thank everybody from the Gertrudis College who helped us in collecting all information we needed in order to draw conclusions. Especially thanks to Principal Frank Looijen for his support during our surveys and measurements in the school.

Anne Cowan

Aris Gkitzias

Paressa Loussos

Delft, November 2012

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Martin van Meijeren

Table of Contents 1. Introduction .................................................................................................................................................................... 6 1.1 Description of the building ................................................................................................................................ 7 1.2 General goals .......................................................................................................................................................... 9 1.3 Research question ................................................................................................................................................. 9 1.4 Chosen classrooms ............................................................................................................................................. 10 1.5 Measurement plan .............................................................................................................................................. 11 1.6 Survey ...................................................................................................................................................................... 11 2. Thermal comfort .......................................................................................................................................................... 12 2.1 Definitions .............................................................................................................................................................. 12 2.2 Requirements........................................................................................................................................................ 14 2.2.1 Standards for thermal comfort ............................................................................................................... 14 2.2.2 Other school studies ................................................................................................................................... 16 2.3 Research method................................................................................................................................................. 17 2.4 Thermal performance ........................................................................................................................................ 18 2.4.1 Survey results ................................................................................................................................................ 18 2.4.2 Analysis method of the thermal measurements .............................................................................. 22 2.4.3 Thermal measurement results ................................................................................................................ 24 2.4.4 Room temperature and use of the sunscreens................................................................................. 28 2.4.5 Relative humidity and Water vapour pressure ................................................................................. 31 2.5 Air quality and velocity ...................................................................................................................................... 33 2.5.1 Survey results ................................................................................................................................................ 33 2.5.2 CO2 measurement results ........................................................................................................................ 34 2.5.3 Velocity measurement results ................................................................................................................ 35 2.6 Simulations in Capsol ......................................................................................................................................... 40 2.6.1 Calibration method..................................................................................................................................... 40 2.6.2 Geometry Input ............................................................................................................................................ 41 2.6.3 Simulation Function references ............................................................................................................. 42 2.6.4 Control of the sun shading....................................................................................................................... 46 2.6.5 Calibration results........................................................................................................................................ 48 2.6.6 Comparison between fabric rollers and louvers .............................................................................. 53 2.6.7 Thermal behaviour of all the rooms ..................................................................................................... 55 2.6.8 Alternatives in the use of the new sunshade .................................................................................... 57 2.7Thermal comfort conclusions .......................................................................................................................... 60 2.7.1 Effects of physical characteristics of the rooms on thermal comfort (sub questions) ........ 60 2.7.2 Effects of the old and new sunshading systems on thermal comfort ...................................... 62 (main research question)..................................................................................................................................... 62

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3. Visual Comfort .............................................................................................................................................................. 64 3.1 Definitions .............................................................................................................................................................. 64 3.1.1 Illuminance .................................................................................................................................................... 64 3.1.2 Daylight factor .............................................................................................................................................. 65 3.1.3 Luminance ..................................................................................................................................................... 65 3.1.4 Discomfort glare and Luminance contrast ......................................................................................... 66 3.1.5 Performance indicators for discomfort glare .................................................................................... 67 3.2 Requirements........................................................................................................................................................ 68 3.2.1 Illuminance Levels requirements ........................................................................................................... 68 3.2.2 Luminance Ratios requirements ............................................................................................................ 69 3.3 Survey results ........................................................................................................................................................ 70 3.4 Illuminance measurements ............................................................................................................................. 72 3.4.1 Measurement method ............................................................................................................................... 73 3.4.2. Results illuminance measurements ..................................................................................................... 74 3.4.3 Illuminance levels Datalogger analysis................................................................................................ 79 3.5 Luminance measurements .............................................................................................................................. 81 3.5.1 Measurement method ............................................................................................................................... 81 3.5.2 Calculation method (LR)............................................................................................................................ 84 3.5.3 Luminance ratio results ............................................................................................................................. 87 3.6 Dialux model ......................................................................................................................................................... 93 3.7 Visual comfort conclusions ........................................................................................................................... 101 4. Conclusions and Recommendations ................................................................................................................ 103 4.1 General conclusions ........................................................................................................................................ 103 4.2 Recommendations ........................................................................................................................................... 105 5. Appendices................................................................................................................................................................. 107 Appendix A: Survey ................................................................................................................................................ 107 Appendix B: Figures of thermal comfort analysis and Capsol simulation .......................................... 111 Appendix C: Tables thermal comfort ............................................................................................................... 127 Appendix D: Hand measurements .................................................................................................................... 129 Appendix E: Figures visual comfort .................................................................................................................. 130 Appendix F: Tables visual comfort .................................................................................................................... 135 Bibliography ................................................................................................................................................................... 145

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1. Introduction

1. Introduction This report offers our research on the indoor comfort of the Gertrudis College in Roosendaal. The research was done because of the placement of a new sunshade system with louvers, which replaced the existing fabric rollers on the west faรงades in August 2012.

In this report we will first start with a general description of the building and the new and old sunshade systems. Also we will discuss the research question. The aim of this report is to see what the thermal and visual comfort is in this school, and to see the difference between the new and the old sunshade systems for the indoor comfort. The sub questions are divided into thermal comfort and visual comfort. In addition we explain the choice of the classrooms, which are used for our study.

This is followed by chapters on the thermal and visual comfort. These two chapters are built up in a similar way. First, important definitions are explained, accompanied by an overview of current standards on indoor comfort parameters. Furthermore we look at other studies conducted for schools. The method we used will be explained, followed by a presentation and discussion of the results, and a comparison of the results to comfort standards.

In order to be able to predict the performance of the sunscreens in future situations and to be able to make a more extensive comparison of the effects of the old and new system on indoor comfort, the classrooms and sunshading systems have been modelled in simulation software. We used Capsol for the thermal comfort and Dialux for visual comfort assessment.

We end with conclusions per chapter, which will contain an answer to the sub research questions.

At the end, conclusions regarding the main research questions are drawn, followed by recommendations and a discussion.

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1. Introduction

1.1 Description of the building The Gertrudis College is a typical Dutch high school in the city of Roosendaal (see Figure 2).

The school was outfitted with a new external sun shading system in August 2012. Therefore, our research will focus mainly on the effect of this intervention on the thermal and visual comfort of the classrooms.

General description of the school The building complex consists of a multifunctional ground floor with two internal patios. At street level there are mainly public uses such as an auditorium, workshops, an indoor sports hall and the administration offices.

Additionally, in the west and east part of the school there is a two-storey wing with educational spaces, such as classrooms, computer rooms and science labs. This wing is divided into three groups, each one of them has a different colour.

Placement of sun shading The new sun shading has been integrated in the south-west faรงade of the school on the first and second floor. Figure 2 shows the spatial articulation of the building and the position of the new shading system and where, at the time of the measurements, the old sunshades were still in place.

Figure 1: Floor plans of school with new and old sunshade systems

Figure 2: Aerial photograph of the Gertrudis College

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1. Introduction

Old sun shading of the building In the north-east faรงades of the buildings there are still external roller shades from fabric sun screens. In addition, most of the classrooms have either internal curtains or internal vertical louvers.

The problem with these external roller shades is that in many rooms they are only computer controlled. Only in some situations like the science lab (see Figure 3) the fabric shades can be manually controlled. The problem in these rooms is that one command controls the sunshades for the whole row, including the adjoining classrooms. This makes it hard to control each classroom separately. Internal sun shading is then extremely necessary.

Another problematic feature of the old sunshade is that it does not close the faรงade completely.

There are still gaps in the bottom and in between two sunshades, which gives unpleasant glare for the students.

Features of the new system For the new system there are external retractable horizontal louvers (venetian blinds) which are centrally controlled by a computer (see Figure 4). In addition they can also be manually controlled for each classroom independently.

The louvers are made out of aluminium and have a white colour (RAL7040), with a reflectivity of around 54% and an emissivity of 0.71. They are connected to the faรงade of every classroom in three places, which makes the span of one louver at least 3.5 meters. Each of the lamellas has a width of 80mm and is 0,4mm thick. They can be controlled to adjust the louver angle.

Figure 3: Inside view of the old sunshade system with fabric rollers

Figure 4: Inside view of the new sunshade system with louvers

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1. Introduction

1.2 General goals The main objectives of this study are as follows: 1. To investigate the influence of sun shading on a) The thermal comfort (including ventilation) b) The visual comfort c) The visual performance 2. To compare the new louver system with the old fabric sun shading and see which one is more effective.

3. To investigate occupants’ perception of the level of thermal and visual comfort in classrooms in general.

4. To conclude which schoolboard system is the best using different sunshade types and positions.

5. To see what the influence is of the sun shading during a whole year, by performing simulations on the computer with Capsol for thermal comfort, and with Dialux for visual comfort.

1.3 Research question In order to achieve these goals, an answer needs to be found to the main research question, which is the most important objective of the research.

Main research question: What is the effect of the new sun shading system of the Gertrudis School on the thermal comfort, visual comfort and the indoor air quality in the classrooms, compared with the existing sunshading?

This main question is divided in sub questions, concerning thermal and visual comfort separately, in order to structure our investigations.

Sub questions of thermal comfort: 1. What is the effect on the thermal comfort in the classrooms under the influence of different sunshade positions and different outdoor conditions, for the new and old sunshade?

1.1 What are the differences in thermal comfort between a room on the top floor and a room on the first floor?

1.2 What are the differences in thermal comfort when a west orientated classroom is compared with an east orientated one?

1.3 How does a corner room, with two external glass façades, differ in terms of thermal comfort from a classroom with one glass façade?

2. What effect do the two different sunshade types have on the air flow and air quality in different situations?

3. What is the influence of the different types of sunscreens on the indoor temperature in extreme conditions? (This will be answered with computer simulations.)

Sub questions of visual comfort: 1. What are the illuminance levels in the classrooms in different sunshade positions, for the new and old sunshade?

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1. Introduction 1.1 How much of the time is artificial light needed, when using the sun shading?

2. What is the general luminance contrast in the classrooms, in different sunshade positions, for the new and old sunshade?

3. What is the influence of the positions of the sunscreens (old and new) on the visibility of whiteboard/ blackboard, TV-screen and smart board?

4. What is the influence of the sunscreens on the illuminance levels in extreme conditions? (This can be answered with computer simulations.)

1.4 Chosen classrooms In order to choose the right spaces for the measurements we have to analyze the different types of classrooms and find the ones with similar characteristics.

In the west wing of the school there are two main types, the classrooms with southwest orientation and the ones with northeast orientation. Our target is also to compare the overall comfort in classrooms in different floors. Thus, we have to find the types with the same features in the 1st, as well as in the 2nd floor.

We focus mainly on the southwest faรงades because the new sun shading system has only been installed at these faรงades (see Figure 5). However, it is also important to know what happens with the old fabric rollers. In the east wing of the school we spotted a classroom (W107) with the proper orientation and with the old sun shade (problem though is the different use of the room as it a science lab).

Figure 5 shows the rooms that are subject of the research.

Figure 5: Floor plans for 1st and 2nd floor, with the rooms that are measured

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1. Introduction

For the Southwest orientation four classrooms are chosen: • G104 which is between two classrooms and it has only one external façade, and the floor is exposed to the outside conditions.

• R203 with two façades exposed to the outdoor condition but only one of them has windows, on the west side of the building.

• R205 with two façades, both with windows exposed to the outdoor condition and with different volume than G104 and R203.

• W107 which is a slightly larger room, on the east side of the building.

For the Northeast orientation only one type is chosen: -R209 which is between two classrooms with only one external façade.

The different classrooms also have different types of sunshading.

-G104, R203 and R205 have the new sunshade -W107 and R209 have the old sunshade There is also a difference in thermal insulation of the roof of the classrooms: -R203, R205, R209, W107 have a roof -G104 has another classroom on top of it, but the floor is exposed to the outside Summarizing, observation of the above mentioned classrooms will provide us information on; • the influence of the new sun shading in two identical classrooms on the first and second floor.

• the thermal comfort in rooms with two external glass façades compared to the ones with only one external façade.

• the differences between classrooms with west-oriented façade and east-oriented façade.

• the effectiveness of the new external system, compared to the old fabric rollers or the use of only the internal curtains.

1.5 Measurement plan For the two different parts of this comfort study, the visual and thermal one, there will also be different measurement plans. These will be explained separately in chapters 2 and 3.

For thermal comfort all rooms are needed from Figure 5 to answer the sub-questions. For visual comfort the rooms R203, W107 and G104 are taken. R203 has the new sunshading and W107 has the old fabric roller-shades, to compare them. Further to answer the question of the visibility of the boards, G104 has a TV-screen, R203 has a whiteboard and W107 has a blackboard.

1.6 Survey Two types of surveys were made. First, a questionnaire for the students, (see Appendix A, Figure A2 and Figure A- 3) in order to get a general idea for the thermal and visual comfort in different classrooms. Secondly, a logbook (or longitudinal questionnaire) was kept up by the teachers (see Appendix A, Figure A- 1), in order to be able to analyze and explain information recorded by the data-loggers.

The outcomes of these surveys will be explained in chapters 2 and 3, concerning the thermal and visual comfort.

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2.1 Thermal comfort, Definitions

2. Thermal comfort This chapter will provide definitions for thermal comfort and indoor air quality and important related aspects. Then, the strategy used to assess the thermal comfort will be discussed. This is followed by the analysis of the survey and measurement results. Finally, also a Capsol model will be presented to simulate different conditions.

2.1 Definitions The parameters that determine the thermal environment are: temperature (air, radiant and surface), humidity and air velocity. The personal information that is important is the clothing and activity level (Olesen, 2001). The things that can influence thermal discomfort are: draught, vertical air temperature differences, radiant temperature asymmetry, and the surface temperature of the floor (Olesen, 2001).

According to Lechner (Lechner, 2009) there are four environmental conditions that allow heat to be lost: Air temperature, humidity, air movement and mean radiant temperature. Especially the combination of temperature and humidity affects the comfort a lot, which can be understood by the psychometric chart (Figure 6).

Figure 6: The comfort zone and various types of discomfort outside that zone are shown in this psychrometic chart (Lechner, 2009)

Temperature [째C] There are different types of temperatures that can be measured: Air temperature (Ta), Globe temperature (Tg), Mean radiant temperature (Tr) and Operative temperature (Top). For this research only the air temperature will be measured.

Relative humidity [%] The relative humidity is the ratio of the water vapour pressure to the maximum vapour pressure possible at the temperature in question (in percentages). Surveys show that the humidity has little effect of thermal comfort, but it is important to measure it in warm and hot conditions (Nicol, Humphreys, & Roaf, 2012). The air quality is experienced by the amount of warmth that is stored in the air (enthalpy). The enthalpy is higher when the temperature and the relative humidity are high 12

2.1 Thermal comfort, Definitions (Leijten & Kurvers, 2007). When the temperature and the relative humidity are both relatively high, this can lower the thermal comfort.

Air velocity [m/s] In school buildings, the occupant density is much higher than for example office buildings (1.82.4m2/person instead of 10m2/person for office buildings) (Clements-Croome, Awbi, Bak贸-Bir贸, Kochhar, & Williams, 2006). Thus, the ventilation is much more critical for the indoor air quality of schools, because of the air contamination.

The air velocity is important in the case of the classrooms in Gertrudis. The air refreshment in this school is done by natural ventilation through windows. Due to high necessary refreshment rates, the velocity near the windows will be high.

Air quality, amount of CO2 [ppm] The air quality is mainly experienced by the people in a building by the amount and type of air pollution in the air, for example chemicals, bacteria, spores, moulds or dust particles (Leijten & Kurvers, 2007). With pollutants it is important that there is enough ventilation to lower the concentration of them in the air. Especially for children the air quality concerning pollutants is important, because they are more vulnerable to them (Bak贸-Bir贸, Clements-Croome, Kochhar, Awbi, & Williams, 2011). The air pollutants, for example spores and moulds, will not be measured in this research, due to the fact that there was not the right equipment for this. The CO2 will be used to determine the air quality.

The CO2 value is an important parameter to determine the air quality of the building and it is a good indicator for ventilation (Valk, 2007). The CO2 concentration in the air is connected to pollution in the air that is emitted by the human body, so it is a good indicator to the quality of the inside air (CO2 Indicator, 2012).

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2.2 Thermal comfort, Requirements

2.2 Requirements 2.2.1 Standards for thermal comfort Temperatures There are at the moment three international standards that relate to thermal comfort: ISO Standard 7730 (2005), ASHRAE Standard 55 (2004) and CEN Standard EN15251 (2007) (Nicol, Humphreys, & Roaf, 2012). These standards concerning thermal comfort will be discussed here.

According to NEN-EN-ISO 7730, the criteria for a classroom (category C), is 24,5° ± 2,5°C in the summer, and 22,0°C ± 3°C in the winter. The maximum mean air velocity in summer should be 0,24m/s and 0,21m/s in the winter (NEN-EN-ISO 7730, 2005). These values are also dependant on the metabolic rate, the clothing factor and the Predicted Percentage Discomfort, and can be found more specifically for different metabolic and clothing values in tables in NEN-EN-ISO 7730.

ASHRAE 55 gives acceptable operative temperature ranges, specifically for naturally conditioned spaces (see Figure 7). Also it gives the optimal temperature for comfort related to the mean outdoor temperature, in equations and in a graph (Nicol, Humphreys, & Roaf, 2012): Tcomf = 0.31T0 + 17.8 °C In this equation T0 is the prevailing mean outdoor temperature.

The maximum and minimum of the acceptable range is given by the following equation: Taccept = 0.31T0 + 17.8 ± Tlim°C The limits differ for the percentage of building occupants who may find the conditions acceptable (Tlim (80%) = 3.5°C and Tlim(90%) = 2.5°C).

Figure 7: Acceptable operative temperature ranges for naturally conditioned spaces, from ASHRAE 55 (Nicol, Humphreys, & Roaf, 2012)

EN15251 gives different values for mechanically conditioned buildings and free-running buildings.

This standard is similar to the ASHREAE 55 standard, but uses data from other projects. For category III (existing building, acceptable level of expectation), there is an equation given with a limit of ±4°C (Nicol, Humphreys, & Roaf, 2012): Tcomf = 0.33 Trm + 18.8 °C In this equation Trm is the exponentially weighted running mean temperature of the outdoor temperature.

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2.2 Thermal comfort, Requirements

Figure 8: Acceptable operative temperature ranges for free-running naturally conditioned spaces (after standard EN15251) (Nicol, Humphreys, & Roaf, 2012)

For the thermal comfort, “Handreiking nieuwe frisse scholen” (Boerstra, Van Dijken, Looijen, Van der Burg, Eekma, & Ten Hoor, 2007) states that the temperature in 90% of the time should at least be 19°C. When outside temperatures are lower than 20°C, the maximum operative temperature should be at 24°C. With outside temperatures above 20°C, the maximum operative temperature should be 4°C above the outside one.

CO2 levels For the air quality, there is agreement that 1200-1500 ppm should be allowed as a maximum value, and 800-1000 ppm CO2 should be aimed for (Valk, 2007). In an urban area the outside air contains about 500ppm, in a rural area 400ppm (Van Ginkel, Wensveen, & Doorgeest, 2008). The average for a classroom is 2500ppm CO2 after a lesson hour according to Valk.

Because the building is from the 1970’s, the requirements for the thermal comfort are not very high. For example, according to the “Handreiking nieuwe frisse Scholen” (Boerstra, Van Dijken, Looijen, Van der Burg, Eekma, & Ten Hoor, 2007), there are different quality classes. For this building we should take class C (this class gives values for an existing school). This class gives, for air quality, a requirement of maximal CO2 concentration of 1200 ppm.

Ventilation The amount of air refreshment is advised to be 750m3 for a classroom of 50m2 (1000m2 for newly built schools), because then even with 30 children in the room the CO2 levels do not exceed 1200ppm (Van Ginkel, Wensveen, & Doorgeest, 2008). For a standard classroom of 3 meter high, this would mean a refreshment rate of 5.

The standard rooms of the Gertrudis College are about 54m2. Boerstra et. al. (2007) also gives guidelines for ventilation. This should be 12,5m3/hour per m2 for 25 students (in a room of 50m2, this implies 25m3 per student per hour).

Also there should be at least 4 operable windows, with at least the half of them at higher that 1.5 meter. This requirement is met in all the classrooms of the Gertrudis College. For avoiding draught the air speed should not be higher than 0,23m/s with closed windows in the summer and 0,19m/s in the winter.

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2.2 Thermal comfort, Requirements

Relative humidity Low values of the relative humidity below 15-20% can cause dryness and irritation of eyes and airways, while too high levels can cause microbial growth (NEN-EN 15251, 2007). According to NEN15251 for category III (acceptable levels for existing buildings), the design criteria for dehumidification is 70%, and for humidification 20%.

With higher temperatures, the discomfort about the air quality rises with higher relative humidity (see Figure 9). For summer it is best to Figure 9: Dissatisfaction concerning the air quality, compared to the have the relative humidity below 60% and in winter below 80% relative humidity.

(Lechner, 2009).

2.2.2 Other school studies Studies in Groningen by the GGD, show that for the indoor environment in high schools, 97% of the investigated schools have values that are unacceptable, even though 80% of them fulfilled the requirements of the Bouwbesluit (Meijer & Duijm, Binnenmilieu in scholen, 2009). The value of 1400ppm is considered unacceptable by the GGD. The study of the GGD (Meijer & Duijm, Binnenmilieu van de openbare scholen in Groningen, 2009) showed that, for some schools, the diagonal ventilation (windows in more than one façade) can render lower CO2 levels than the ventilation though a single façade.

This GGD study also showed that 98% of the time, the CO2 value during the study hours during five days was at least 2600 ppm. The percentage of time that the CO2 value was above 1400 ppm during a lesson hour is not given for High Schools, but for Primary Education and Special education, this is 27 respectively 11% of the time. For naturally ventilated rooms this was 29,1% for Primary Education. As expected, the CO2 levels for naturally ventilated rooms (2737ppm) were higher than mechanically ventilated rooms (1989 ppm).

The optimal temperature is advised to be between 19-23°C. In the GGD study for High schools, about 8% of the time the temperature is above 23°C. The average values for the relative humidity in high schools are 45%, with an average outside temperature of 5,2°C. During this time, for 80% of the classrooms, the RH never goes above 60%, and only for lower than 1% of the classrooms the relative humidity goes above 60% half of the time.

Often the air quality in schools with natural ventilation is quite bad, for example in research of Polish schools the ventilation rate comes in the range of 2-6m3/h, instead of the required 20m3/h, with very high CO2 concentrations of 4200ppm (Sowa, Wachenfeldt, Panek, & Aschehoug, 2006).

Also research of Finnish schools (Kurnitski & Palonen, 2006) show results from measurements in classrooms, which have an average of 1,6l/s (5,8m3/h) for naturally ventilated schools, much lower than 5,5l/s for mechanically ventilated classrooms (19,8m3/h). But even in the Netherlands it is apparent that in general the air quality is bad in high school.

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2.3 Thermal comfort, Research method

2.3 Research method In comfort studies there are four main research parameters that should be investigated (Nicol, Humphreys, & Roaf, 2012): Physical measurements, personal variables, subjective measures and behaviour. All these factors were investigated during this research, as well as others, like the room characteristics.

Survey (general questionnaire) In the survey, the personal variables (clothing insulation) and subjective measures (for example thermal experience and preference) were investigated via a questionnaire (see Appendix A, Figure A- 2 and Figure A- 3). Concerning the personal variables, the questionnaire focused on the clothing insulation (clo). Also the metabolic rate is important, but since all students mainly sit during a lesson it was assumed that they have a low metabolic rate.

Concluding, the thermal comfort will be measured by taking: • Personal measurements (clothing insulation) • Subjective measurements (thermal comfort vote and preference for change) Behaviour (longitudinal questionnaire/ logbook) During the survey also the user behaviour was noted. For example; if the doors are opened or closed, the positions of the solar shading, if the artificial lighting is on and what kind of blackboard/smartboard they are using.

Objective physical measurements There are four important physical variables for thermal comfort (Nicol, Humphreys, & Roaf, 2012): a) Air temperature (Ta) [C] b) Radiant temperature and mean radiant temperature (Tr) [C] c) Air velocity [m/s] d) Water vapour pressure (Pa). This will be calculated with the help of the Relative humidity [%].

For the air quality the CO2 levels [ppm] were measured.

We do two types of measuring: • Measuring with devices manually on site (air temperature, CO2 levels, relative humidity and air velocity) • Measuring with data loggers (air temperature, relative humidity and illuminance [lux]).

The necessity of the hand-measurements has to do with: • greater accuracy in the measurements and check if there are significant temperature fluctuations in different spots inside the rooms (if there is for example different temperature close to the façade area, especially during clear sky, or close to the corridor area) • better simulation of the different conditions related to the use of the sun shade.

• measurement of all types of temperatures , Ta, Tr and Tg In this research only the air temperature Ta was measured and used, which could be done with both dataloggers and hand measuring equipment.

The data-loggers record measurements every ten minutes during the whole measuring period.

These data-loggers are placed in a specific point (next to the blackboard) in the room. But also hand measurement needed to be done at the time of the surveys. This way, measurements on multiple places in a classroom can be made and read out easily.

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2.3 Thermal comfort, Research method The air velocity was measured with a hot-wire anemometer. In general, the velocity is difficult to measure, because it changes a lot even over a relatively short period of time of 5 minutes. Mainly, this happens because it is very dependent on directionality. Therefore, during the velocity measurements, the maximum and minimum is taken over a period of two minutes, this was used to calculate the average.

2.4 Thermal performance 2.4.1 Survey results Previous measurements showed that temperatures often did not deviate a lot at different points in one room, but sometimes temperature differences up to 1°C were visible (see Appendix D, Figure D- 1 and Figure D- 2). But since there was limited time during the surveys, only a single temperature measurement was made in the middle of the room.

The outcome of the survey should enable us to say something about the pupils’ experience over the room temperature, together with the preferred sensation.

It is not possible to derive an obvious relationship between the temperature experience and the actual room temperatures while conducting the survey, see Figure 10 and Figure 12. In Figure 10 at all temperatures about 60% of the students experience the temperature as comfortable, with approximately 10-20% (comfortable) warm and 20-25% (comfortable) cold. There is a slight slope in the figure, less people find it cold at a higher temperature and more people find it warm. Only between 22,8°C and 23,4°C there is a higher percentage of students who find it cold. To see if this is caused by the clothing factor, in Figure 11 the average clothing factor per experience is shown.

But in this figure it is not evident that the students had a lower clothing factor between 22,8°C and 23,4°C.

Temperature experience 100%

21 pupils

38 pupils

81 pupils

57 pupils

21,4-22,0°C

22,1-22,7°C

22,8-23,4°C

23,5-24,1°C

90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Too warm (-2)

Comfortable warm (-1)

Comfortable cold (1)

Too cold (2)

Comfortable (0)

Figure 10: Survey result, experience for the temperature

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2.4 Thermal comfort, Thermal performance

Temperature vs. average clothing, temperature experience 1,2

1

Clothing factor

0,8

0,6

0,4

0,2

23,7

23,6

23

22,9

22,8

22,7

22,5

21,8

0 Temperature ( °C) Figure 11: Temperature against the clothing factor during survey, temperature experience

Concerning the temperature preference, Figure 12 shows the temperature preference per measured temperature range. Students seem to want the least change in temperature between 21,4°C and 22°C. Above 22°C more students prefer a change in temperature. Again this cannot be explained with Figure 13, where the different preferences are put in a graph with the clothing factor and temperature.

Temperature Preference 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

21 pupils

38 pupils

81 pupils

57 pupils

21,4-22,0°C

22,1-22,7°C

22,8-23,4°C

23,5-24,1°C

Warmer (-1)

No change (0)

Colder (1)

Figure 12: Survey result, preference for the temperature.

19

2.4 Thermal comfort, Thermal performance

Temperature vs. average clothing, temperature preference 1,2

Clothing factor

1

0,8

0,6

0,4

0,2

23,7

23,6

23

22,9

22,8

22,7

22,5

21,8

0 Temperature ( 째C) Figure 13: Temperature against the clothing factor during the survey, temperature preference

The average temperature preference was slightly lower than zero, which means that they preferred to have the temperature slightly warmer (see appendix A, Figure A- 4). The average temperature experienced was between comfortable and comfortable cold (see appendix A, Figure A- 5). Thus we can conclude from these figures that, in majority, the rooms were experienced as comfortable at all measured temperatures during the survey, even though the temperature was experienced as slightly cold. For the temperature experience, there was not a difference for the given zones of the room (see Appendix A, Figure A- 6).This might be because this was a general survey, and the children do not sit at the same place every lesson and every day (otherwise for example children always sitting next to a window might experience the room colder).

The more clothing the students wear, the lower the experienced temperature (Figure 14). This might be explained by the fact that the colder the people are, the more clothing they wear. Also, the more clothing the students wear, the warmer they would prefer the temperature (Figure 15).

20

2.4 Thermal comfort, Thermal performance

Temperature experience

3 2 1 0 0

0,2

0,4

0,6

0,8

1

1,2

-1 -2 -3

clothing insulation 2 Too cold 1 Comfortable cold 0 Comfortable -1 Comfortable warm -2 Too warm…

Figure 14: Survey results: temperature experience correlated with clothing insulation, with regression line

Temperature preference

2

1

0 0

0,2

0,4

0,6

0,8

1

1,2

-1

-2 clothing insulation 1 Colder 0 No change -1 Warmer Figure 15: Survey results: Temperature preference correlated with clothing insulation, with regression line

Comfort temperature For calculating the mean comfort temperature, Griffiths’ method will be used. This method can also be used in a smaller sample of comfort votes (Nicol, Humphreys, & Roaf, 2012).

The comfort temperature can be calculated with the following equation: Tcomf = Top – (C-CN)/G Tcomf = Comfort temperature (°C) Top = Actual operative temperature (°C) C = Comfort vote (deviates from -2 to 2 in this survey) CN = Numerical value of C for neutrality (0 in all cases) G = Griffiths slope (K-1) Surveys found that the most likely value for the Griffiths slope is about 0,5K-1 (Nicol, Humphreys, & Roaf, 2012). When using this equation with G=0.5K-1 for all separate students, the average comfort temperature is 22.3°C.

21

2.4 Thermal comfort, Thermal performance

2.4.2 Analysis method of the thermal measurements In order to assess the thermal comfort, the most important parameters, room (air) temperature and relative humidity, are recorded by data-loggers for a time span of two weeks. To be able to explain the values of these loggers, the tutors using the measured rooms were asked to keep up a logbook. This was done only for rooms G104, R205 and R209, with a maximum of five days. For this time span, the state of the sunscreen and other parameters such as lighting and ventilation were written down in the logbook (longitudinal questionnaire).

Although this method was the only feasible way of assessing the measurement conditions, it is not ideal, because the logbook records were made only at the start of every lesson. A higher frequency would have given more accurate results since the conditions are likely to change during a lesson.

Unfortunately, the records were not always taken in consecutive days as well, so comparing the classrooms is difficult.

Another data source was provided by the controller of the new sunshade system. By reading out the history of this control module (which stores data on the position of the screen and the rotation of the louvers), a very accurate image of the usage is obtained. It is not possible to read out the controller of the old sunshade system, therefore we need the logbook in order to report the usage during the data-logger measurements.

Due to a defect data-logger in W107, no data was obtained for this room. This does not endanger the ability to compare the old and new sunshading since room R209 (fabric roller, with an east façade) is recorded too.

An important fact to note is that in the following graphs of the datalogger output, the beginning of a day is shown as: the name of the day, followed by 24:00.

Outside conditions Before discussing the measurements outcomes, it is important to give a short impression of the exterior conditions during the measurements.

Figure 16 shows the condition of the sky during weeks 39 and 40. Both weeks were mostly overcast, except for the weekends in which a clear sky occurred. This is confirmed in the graph in Figure 17, which gives the global and direct radiation data (horizontal plane) that belong to the occurring sky conditions. The weekends show peaks in global and direct radiation, with a proportional division over the course of a day.

The direct radiation values (see Figure 17) are derived from the KNMI data for global radiation (measured in Woensdrecht) by using the method of derivation as described by Velds (Velds, 1989).

More specific, the formulas of De Jong have been used, which are derived from hourly data of De Bilt. When focusing on the weekdays only (relevant for the occupancy), the rooms were exposed to more direct radiation in week 39 than in week 40, especially near the weekend. In week 40, two days form an exception to the very overcast conditions: Monday and Thursday. During the rest of the week, the direct radiation did not exceed 150 W/m2. Despite these lower radiation values, the outside temperature was on average higher than in week 39 (which had low temperatures at clear nights).

Both weekends (especially the second one) show complete clear sky conditions, providing good conditions for a review of the performance of the sunscreens from a thermal point of view.

Considering the fact that the sunscreen is controlled by an outside light intensity threshold, week 39 provides more suitable conditions for a closer look to the performance of the sunscreens and their influence on the thermal comfort during occupied hours. For this week information from the tutors’ logbooks is available. Unfortunately, it was only possible to read out the history from the sunscreen controller from week 40 on. On the contrary, the second week lacks logbook data.

22

2.4 Thermal comfort, Thermal performance

23

9

21

8

19

7

17

6

15

5

13

4

11

3

9

2

7

1

5

0

Sky condition (9=full overcast)

Outside temperature

Figure 16: Exterior conditions, week 39 and 40

Global and direct radiation (W/m2)

600,0

500,0

400,0

300,0

200,0

100,0

0,0

Global radiation

Direct radiation

Figure 17: Direct radiation as part of global radiation, week 39 and 40

23

Sky condition

Exterior temperature (째C)

Therefore, the following discussion of the results will be composed of outcomes from week 39 and 40, depending on the subject and the room.

2.4 Thermal comfort, Thermal performance

2.4.3 Thermal measurement results General discussion – all rooms Larger differences between the room temperatures can be observed in week 39 than in week 40.

This is a result of the absence of solar gains in the second week (Figure 17), which limits the differences between the various room temperatures to less than one degree. In general, the temperatures are within a 17 to 21 degree range for almost all cases. Maximum fluctuations do occur in classrooms G104 (especially week 40) and R203, which reach day-night fluctuations of five degrees. Fluctuations in R205 and R209 are 1 or 2 degrees less.

Figure 18 and Figure 19 justify the preliminary conclusion that the internal gains due to occupancy have a big impact on the thermal behavior of the rooms, since temperature peaks in the scale of the weekdays are absent during weekends. Therefore, the weekends provide a better basis for comparing the rooms in terms of the effect of physical parameters such as orientation, amount of glass and the amount of outside-exposed construction on the thermal aspects. Both weekends have clear sky outside conditions, so solar gains will influence the rooms as well.

23,0

Temperature (°C, hourly)

21,0 19,0 17,0 15,0 13,0 11,0 9,0 7,0 5,0

R209

R203

G104

R205

Outside

Figure 18: Room temperatures resulting from the data-loggers, week 39 23,0 21,0

Temperature (°C, hourly)

19,0 17,0 15,0 13,0 11,0 9,0 7,0 5,0 Sun 09/30 24:00

8

16 Mon. 24:00

8

16

R209

Tu. 24:00

8

16 Wed. 24:00

R203

8

G104

16

Thu. 24:00

8

R205

16

Fri. 24:00

8

Outside

Figure 19: Room temperatures resulting from the data-loggers, week 40

24

16

Sat. 10/6 24:00

8

2.4 Thermal comfort, Thermal performance Effect of exposed walls or floors in the indoor temperature Rooms R203 and G104 show identical temperature curves during the weekends (except for Saturday 29th), and a day-night range of 17 to 19°C which is significantly smaller than during the weeks. Low room temperatures occur during cold nights. This can be explained by the physical properties of these rooms and their position within the building. G104, on the first floor, has a floor slab exposed to exterior conditions, which will have a cooling effect on the room. The same goes in a slightly smaller extent for the north orientated (brick) wall of R203.

R205 contains an extra wall exposed to outside conditions as well, but the orientation of this wall is south, which is beneficial in terms of solar gains. R209, which does not drop to such minimum temperatures during night, is situated in between two classrooms, but it also has a roof. The fact that R203 is positioned on the second floor (containing a flat roof), and G104 is first floor, barely seems to influence the maximum temperatures.

Effect of the facade orientation in the indoor temperature The effect of the room orientation can be derived from the weekend data as well. R209, containing an east-orientated glass façade, shows temperature peaks relatively early, around 12:00. The remaining, west orientated, classrooms R203, R205 and G104 reach their maximum temperatures beyond normal lesson hours, around 16:00 or 17:00. In the first weekend before week 39, this temperature shift due to the orientation is evident. R205, containing a flat roof and a second south glass façade, is on average one degree warmer throughout the whole day. Differences in outside temperature do have a small influence on the rooms; see Saturday 22nd and Sunday 23rd.

The rooms do not exceed 22°C, even when the outside temperature is high (e.g. Monday 1st of October) and more direct radiation occurs. Most probably the sunshading worked well in these situations. An overview of the measured temperatures during weekdays between 08:00 and 17:00 is provided in Table 1: Table 1: Room temperatures between 08:00 and 17:00

Week 39 Tmin (°C) Tmax (°C) Tavg (°C) Week 40 Tmin (°C) Tmax (°C) Tavg (°C)

R209

R203

G104

R205

Outside

17.6 21.1 19.9

16.8 21.0 19.7

16.8 22.1 19.8

19.0 21.8 20.5

12.9 19.1 15.3

19.1 22.0 20.3

17.8 21.5 20.3

18.0 22.0 20.4

19.2 22.5 20.8

10.6 20.7 15.9

Despite the overcast sky, week 40 is the warmest (outside and thus inside). Table 1 also shows that R205 is on average more than 0.5 degree warmer than the other classrooms, a trend that was visible in Figure 18 as well and is explained before.

25

2.4 Thermal comfort, Thermal performance Review of temperature requirements An overview of various requirements on comfortable temperatures in classrooms has been given in paragraph 2.2.1 Standards for thermal comfort. Since the measurements are taken at the end of September and start of October, we are between winter and summer. The outside conditions are relatively cold (see Table 1), leading to maximum occurring room temperatures below 22.5°C. Average temperatures (day and night) for week 39 and 40 were resp. 12.4 and 13.9°C. Temperature requirements for winter: 1. NEN-EN-7730 prescribes Tcomf =22,0°C ± 3°C. 2. Having an outside average temperature of 14°C, ASHRAE Standard 55, predicts that less than 80% of the occupants will find the thermal conditions acceptable if the temperature drops more than 3.5 degree below 22°C , while 90% at 2.5 degree colder than 22°C. 3. The “Handreiking Frisse Scholen” requires a minimum temperature of 19°C for more than 90% of the occupation time.

Thus, 19oC is the limit for the lowest comfortable indoor temperature at that period.

In general, room R205 seems to be the only room matching these requirements during occupied hours (between 08:00 and 17:00) for both weeks. In case of the other rooms, temperatures below 19°C are common during the first hour of the day, especially in room G104.

Further analysis of the temperature data (see Table 2) reveals that the first week is critical with some cold nights and lower daily averages. R209 (east oriented) comes close to meeting the requirements, while the room temperatures of R203 and G104 are below 19°C during circa 20% of the occupied time between 08:00 and 17:00. According to ASHRAE standard 55, 10-20% of the occupants have considered these conditions uncomfortable. In week 40, all rooms are above the minimum temperature for more than 90% of the time.

Table 2: Time that room temperatures are above 19°C, as percentage of total occupied time

Room Week 39 Between 08:00 - 17:00 Between 09:00 - 17:00 Week 40 Between 08:00 - 17:00 Between 09:00 - 17:00

R209

R03

G104

R205

89 % 97 %

78 % 86 %

77 % 86 %

97 % 100 %

96 % 100 %

93 % 97 %

91 % 97 %

99 % 100 %

At 09:40, after the start of the first lessons, R209 meets the requirements as well. R203 and G104 are still too cold in week 39. Of course radiators are available in the rooms, but most probably they are not used yet.

For week 40 all rooms are within the comfortable range.

The room temperatures do never even approach the maximum allowed temperature levels that are given by the different institutes that are mentioned. Even on days with high direct radiation (Figure 17), room temperatures stayed below 23 degrees. Most of the time, the peak temperatures are around the desired temperature of 22°C. Summer conditions are simulated in the Capsol software (see chapter 2.6.6 Comparison between fabric rollers and louvers).

26

2.4 Thermal comfort, Thermal performance Room temperature and occupancy– Room R209 Table 3 (below) contains the number of hours each room was used, which shows that room R203 is used more frequent during both weeks. The same goes for G104 in the second week, causing bigger maximum temperatures during the day.

Table 3: Room occupation, hours per day for week 39 and 40

Week 39 G104 R203 R205 R209 Week 40 G104 R203 R205 R209

Monday

Tuesday

Wed/day

Thursday

Friday

Total

9 6 6 6

5 7 7 4

3 7 8 4

4 7 2 4

2 7 5 3

24 34 28 22

7 6 6 5

6 8 5 3

8 4 7 4

6 8 4 2

8 5 6 4

35 31 28 18

In Figure 20 and Figure 21, R209, contrary to other rooms, is mostly occupied in the mornings only, something which causes the temperature peak at 12:00. Another conclusion from the occupancy graphs is that the internal heat load produced by persons in the room has immediate impact on the rise of the room temperature, more than all other factors. The graphs for room R209 only function as an example. The other rooms show identical reactions (see Appendix B, Figure B- 1 and Figure B- 2).

24

30

22 20 20 18 16

15

14 10 12 5 10 8

0

Mon. 6:00 12:00 18:00 Tu. 6:00 12:00 18:00 Wed. 6:00 12:00 18:00 Thu. 6:00 12:00 18:00 Fri. 6:00 12:00 18:00 Sat. 09/24 09/25 26/12 09/27 09/28 09/29 24:00 24:00 24:00 24:00 24:00 24:00

Pupils (schedule)

Pupils (logbook)

Outside temperature

Room temperature

Figure 20: Occupancy in room R209 week 39, against inside temperatures

27

Number of pupils

Room temperature (°C)

25

2.4 Thermal comfort, Thermal performance

28 24,0

26 24

Room temperature (°C)

22,0

22 20

20,0

18 18,0

16 14

16,0

12 10

14,0

8 12,0

6 4

10,0

2 8,0 Mon. 10/1 24:00

0 8:00

16:00

Tue. 10/2 24:00

8:00

16:00

pupils present

Wed. 10/3 24:00

8:00

16:00

Thu 10/4 24:00

Room temperature

8:00

16:00 Fri 10/5 8:00 24:00

16:00

Sat 10/6 24:00

8:00

Outside temperature

Figure 21: Occupancy in room R209 week 40, against the inside temperatures and the lesson turns.

When we zoom out, and go back to the temperature graphs for all rooms in Figure 18 and Figure 19, it is possible to say something about the influence of the internal gains in general. The reason for the fact that R203 and G104 do fluctuate more than the other rooms, lies, beside physical parameters, in occupation.

Room temperature and ventilation – Room R209 Sometimes even temperature drops occur in the short period in between two consecutive lessons, which must be related to a higher ventilation rate. In order to make this understandable, lines at lesson changes are added to Figure 21. When students leave the room, doors are opened, and the ventilation rates increase. Details for one day (Friday 5th) can be found in Appendix B, Figure B- 4.

Ventilation rates are hard to be reconstructed based on information from the logbooks, because (we assume that) tutors only kept records during occupied hours. With one record every lesson hour, it is hard to predict exactly the ventilation rate since parameters that influence the air refreshment (open windows or door) are very likely to change during one lesson.

In the afternoons, the temperature starts to decrease again, also because this east room lacks direct sun.

2.4.4 Room temperature and use of the sunscreens Room temperature and use of fabric rollers - R209 Before the analysis of how the rollers are used, it is necessary to mention that the earlier comparison between the occupancy according to the logbook and the schools official schedule (see Figure 20), showed that the logbook is filled in for 18 out of 22 occupied hours. Since R209 was only occupied in the mornings and the fact that it is east orientated, the logbook covers all the hours the sunscreen could have been down because of direct sunlight.

In Figure 22, the use of the fabric rollers during week 39 has been plotted. Although drawing a conclusion for this is still hard, we can see that the rollers were down only during two hours on Tuesday (25/09). In Figure 17 we noticed that on this Tuesday morning KNMI measured significantly more direct radiation (above 300 W/m2) than on other weekdays. The fabric roller does seem to influence the temperature. Unfortunately, no data is available for the weekend, 28

2.4 Thermal comfort, Thermal performance although the sunshading is probably down on Saturday and Sunday. Despite the solar loads, temperatures do not show expected peaks before 12:00.

2 24,0

20,0

Position sunshading

Room temperature (째C)

22,0

18,0

1

16,0 14,0 12,0 10,0 8,0

0

Fabric roller down (2=yes, 1=no)

Outside temperature

Room temperature

Figure 22: Room R209 week 39, temperatures against the fabric roller position

Room temperature and use of louvers - G104, R205 From the control system of the new sunshading, data on the usage of the screens in classrooms G104 and R205 could be extracted, displayed in Figure 23 and Figure 24. With a few exceptions, the sunscreen is down from 9:30 till 16:30h on Monday and Thursday, two days with a lot of sun.

The louvers seem to reduce the solar gains successfully since the room temperatures hardly exceed 22째C, a temperature similar to days with small solar gains. In overcast situations, like Sunday and Friday, the screens are up which means the system works well. Wednesday night formed an exception, most probably the control system did not function well.

However, sometimes the system does show unexpected behaviour. The effect in the room temperature due to these differences will be analysed in the following paragraphs.

5 24,0

Room temperature (째C)

22,0

4

20,0 3

18,0 16,0

2 14,0 12,0

1

10,0 8,0

0

Position sunscreen (0=up, 1=half closed horizontal, 2=lamels horizontal, 3=lamels 30, 4=lamels 55, 5=lamels vertical) Outside temperature

Figure 23: Room G104 week 40, temperatures against the sunshade position 29

2.4 Thermal comfort, Thermal performance

5 22,0

4

20,0 3

18,0 16,0

2

14,0 12,0

1

Position sunshade

Room temperature (°C)

24,0

10,0 8,0

0

Position West sunscreen (0=up, 1=half closed horizontal, 2=lamels horizontal, 3=lamels 30, 4=lamels 55, 5=lamels vertical) Position South sunscreen Outside temperature Room temperature

Figure 24: Room R205 week 40, temperatures against sunshade position

Effect of different positions of the louvers in the indoor temperature of G104-R205 (during weekend 29th-30th] The afternoon of Saturday the 29th, the screen was up during a period of direct sun on the façade around 16:00. This caused a peak in the temperature of G104. In contrast to room G104, the sunscreen worked in R205 on Saturday the 29th (see Figure 24) resulting in a room temperature that was two degrees lower than G104. This is a very interesting comparison, since the weekend does not contain unknown parameters such as ventilation rates, nor occupancy. Thus, this difference can be seen as a direct effect of the use of the new sunscreen.

Effect of different rotation of the louvers in the indoor temperature of G104-R205 The effects of different louver configurations were examined thoroughly during the weekend of September 29th, in Figure 24. Until 11:00, both sun screens of R205 were down with louvers completely closed (vertical). After that, in both rooms louver rotation changed to 30°C (less opaque, almost horizontal), resulting in an immediate temperature increase of one degree. After 12:00, when the sun moved away from the south façade, its sunscreen went up, while the screen on the west façade closes more to 55° around 15:00 and finally to completely closed after 17:00.

From 15:00, the room temperature stabilised at 22°C. A further temperature increase during the low west sunset was prevented by the change in louver rotation. So, although the differences between the rotations of the louvers are small, an effect of on the rooms’ temperature is noticeable.

Additionally, in Figure 24, similar control actions take place on Monday October 1st, which was another sunny day. With students inside the room, the temperature levels are two degrees higher than during the weekend, but more closed louvers (both systems) still did prevent the room from heating up. As soon as the configuration of the screens changed to less opaque (horizontal/half open) during the last two lessons at 15:00, the temperature increased to 23°C due to the direct sun.

Summarizing, the conclusions of the sunscreens use are: The influence of both systems is more clear during the weekends (no uncertain cooling parameters e.g. ventilation). Saturday 29th and Sunday 30th of September are very suitable because they are between week 39 and 40, (see Figure 22, Figure 23 and Figure 24).

30

2.4 Thermal comfort, Thermal performance

Both systems seem to work properly on thermal control as the temperatures in R203 and R209 during this weekend, justify our conclusion that both systems successfully reduce the temperature peaks from direct solar gains if the sunscreen is applied.

On the few weekdays with high direct radiation values, the room temperature can be kept at levels that are similar to days with an overcast situation (for all rooms). Peaks and big temperature differences between the rooms during the week should mainly be assigned to internal gains and not to external gains.

Less opaque louver configurations seem to be sufficient in order to maintain the room temperature comfortably at 22°C. The fact that the louvers in R205 are in a more closed configuration than in G104, indicates that the less opaque configurations (horizontal and 30°) are insufficient in terms of visual comfort. This means louvers were not closed because of thermal discomfort, but because a less opaque configuration caused glare which hindered the tutor in performing his lesson tasks.

2.4.5 Relative humidity and Water vapour pressure The relative humidity of the different classrooms, measured by data-loggers over a longer period, is plotted in Figure 25. The rooms have the following relative humidity: 61% for R203 and G104, and 57% for R205. R205 has a lower relative humidity than the rest. This might be because of better ventilation, because the classroom is slightly bigger than the other two, or only because of the higher temperature. In summer it is best to keep the relative humidity below 60-70%. The values sometimes exceed the value of 70%, especially R203, and sometimes G104. R205 stays under the 70%.

100,0

Relative Humidity (%, hourly)

90,0

80,0

70,0

60,0

50,0

40,0

R203

G104

R205

Outside

Figure 25: Relative humidity R203, G104, R205 and outside

The relative humidity can be translated to Water vapour pressure Pa [kPa], with the following formulas (Van der Linden, 2006):

4030.18 ⎞ ⎛ pmax = 100exp ⎜18.956 − ⎟ T + 235 ⎠ ⎝

The meaning of the symbols are: pmax the maximum vapour pressure in Pa T the temperature in °C

And: 31

2.4 Thermal comfort, Thermal performance

ϕ=

p pmax

p φ

⋅ 100%

vapour pressure relative humidity in %

Figure 26 shows that the vapour pressure is between 1000 and 1200 Pa during the weekends.

During occupied hours high peaks occur, which lower when the students leave the classrooms between 12 and 4 PM. This graph confirms that R205 has lower vapour pressure than the other rooms.

2

2000

Vapour pressure (Pa, hourly)

1800

1600

1

1400

1200

1000

800 Fri. 09/21 24:00

12

Sat. 09/22 24:00

12

Sun. 24:00

12

Mon. 24:00

Rain occurrence (1=yes)

12

Tu. 24:00

R203

12

Wed. 24:00

G104

12

Thu. 24:00

12

R205

Fri. 24:00

12

Sat. 24:00

12

0 Sun 09/30 24:00

Outside

Figure 26: Vapour pressure R203, G104 and R205 for week 39, related to the occurrence of rain

Requirements fulfilment RH Relative humidity values that are not within the range of 20 to 70% need (de)humidification, according to (NEN-EN 15251, 2007). Figure 25 has shown that relative humidity values never go below 45 %, but they do exceed the 70% at some points. Especially R203 and G104 contain a few peaks that are quite high. In the few cases the 70% is exceeded, it is not by a significant amount, therefore it can be considered as acceptable.

Compared to other classroom studies, for example the study of the GGD (Meijer & Duijm, Binnenmilieu van de openbare scholen in Groningen, 2009), the relative humidity values seem slightly high. In the GGD study for High schools, the average value for the relative humidity was 45%, but with an average outside temperature of 5,2°C. The outside temperatures at the time of the data-logger measurements were not that low, which is probably the reason why the average relative humidity is higher.

32

2.5 Thermal comfort, Air quality and velocity

2.5 Air quality and velocity This chapter will discuss the possible relation between the ventilation rates and the different sunshades.

2.5.1 Survey results For the survey, in total 58% of the students experience draught (Figure 27), and 62% also found the air stale or musty (Figure 28). It is not possible to assign the draught problems to specific positions within the classroom, because the survey had a general character and the students can sit at different locations in other lessons.

Do you sometimes suffer from drafts? (yes)

Do you find the air stale or musty sometimes?

93%

64% 61% 58%

64%

72%

64%

58%

39%

39%

Figure 27: Survey result, percentage of people who suffer from draughts in different situations

62%

62% 48%

Figure 28: Survey result, percentage of people who find the air stale or musty in different situations

Do you experience draught?

35 30 % of students

25 20 Yes

15

No

10 5 0 Zone A

Zone B

Zone C

Zone D

Figure 29: Survey results: experience of draught in different zones of the room

33

Figure 30: Zones made to analyze results of the survey

2. 5 Thermal comfort, Air quality and velocity

2.5.2 CO2 measurement results

CO2 levels 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 0 windows 1 window 1 window 2 windows 3-5 + door windows 0 windows

1 window

1 window + door

2 windows

3-5 windows

Figure 31 shows that the more windows are opened, the lower the CO2 levels. With 3 to 5 windows opened and door closed, the amount of CO2 stays around the maximum allowed value of 1200ppm. When there are no students in the room for a longer time, the CO2 levels are 500800ppm (see Appendix D, Figure D1 and Figure D- 2).

With 3-5 windows opened the refreshment rate was assumed to be between 4.5 and 7.5 air changes per hour, which means that these are the only refreshment rates at which the classrooms will fulfil the requirements.

Figure 31: Measurement results during survey: CO2 levels, depending on the amount of opened doors and windows

Figure 32 does not show much difference for the experience of the room concerning air quality with different CO2 levels. The students that were in the room with 1200 ppm CO2 found the air the least stale, but still almost 50% of the students were displeased with the air. Above 1700 there was not much difference in the people who found the air stale or musty. This might also be because this was a general survey, and they might talk about the situation in the classrooms in general.

CO2 levels: Do you find the air stale/musty? (% YES) 80% 70% 60% 50% 40% 30% 20% 10% 0% 1230

1750

1780

3200

4510

CO2 levels (ppm) Figure 32: Survey result, percentage of people who found the air must, compared to the CO2 levels

The survey showed that almost 60% of the children experience draught at some point. This is probably because so many windows need to be open to make the CO2 levels low enough to meet the requirements.

For the air quality, 1200ppm is the maximum that is allowed according to the requirements. But at this concentration (1230ppm) during the survey, almost 50% of the students are displeased already.

34

2.5 Thermal comfort, Air quality and velocity

2.5.3 Velocity measurement results The new louver sunshading system has a large span of more than 3,5 meters wide, which makes it more vulnerable to wind. When the velocity of the wind exceeds 12m/s for at least 5 seconds, the sunshading will always go up automatically to prevent damage. For all velocities below 12 m/s, the system works properly if there is too much solar radiation. In closed position, it is still possible to open a window in order to ventilate.

The fact that new sunshading system (in contrast to the old fabric rollers) covers the façade completely might have an influence on the air velocity. It is reasonable that a sunshade system which is close to the glazing decreases the velocity at window openings and thus the ventilation rate in a room. The influence of the old and new sunshading on the air velocity will be examined.

Velocity of new sunshade system (G104) The influence of the new sunshade system on the ventilation rates will be examined in room G104.

These ventilation measurements were made on 26-09-2012 (week 39). The average outside velocity on that day between 09:00 and 16:00 was 4,3m/s (Woensdrecht data KNMI).

Figure 33: Inside view of room G104 towards the outer façade

Different sunshade positions To see the influence of the solar shade on the ventilation rate, the velocity is at the opening of the windows were measured with different conditions of solar shading. These measurements were done in room G104. These different positions of shading were done when all 4 windows and the door were opened.

To see if there is a significant difference between the upper and the lower rows of windows, first the four windows are divided into upper and lower rows. The louvers stop at the bottom of the glass windows, so the velocities there might be higher. There were measurements made for the lower windows (1 and 3) and for the upper windows (2 and 4). See appendix C, Table C- 1 and Table C- 2 for more detailed values for each window.

Table 4: Average velocities for G104 for upper and lower windows in different sunshade positions

Angle of louvers

Average velocity lower windows (1 and 3) (m/s) No louvers 1,74 Horizontal 1,88 45° 1,5 Vertical 1,35 Average velocity of all 1,62±0,39 positions 35

Average velocity upper windows (2 and 4) (m/s) 1,15 2,17 1,18 1,24 1,44±0,59

2. 5 Thermal comfort, Air quality and velocity There is not a large difference between the velocities in the upper windows and the lower windows. Therefore we can assume that all four windows can be considered the same, to derive an average of four different measurements per louver position (see Table 5).

Table 5: Average velocities for G104 for different sunshade positions

Angle of louvers

Average velocity window1

Average velocity window2

Average velocity window 3

Average velocity window 4

No louvers Horizontal 45° Vertical

1,73 2,51 1,58 1,50

0,78 2,02 1,78 1,19

1,75 1,50 1,21 1,20

1,51 2,33 0,58 1,30

Average velocity all windows (m/s) 1,44±0,39 2,09±0,38 1,28±0,46 1,30±0,13

Standard deviation of averagesG104

3

Velocity (m/s)

2,5 2 Max. S.D.

1,5

Min. S.D. 1

Average

0,5 0 No louvers

Horizontal

45 °

Vertical

Figure 34: Average of the average values of the four windows, with the standard deviation

It becomes evident that there are not enough measurements made to make real conclusions for the velocity. But it seems like the averages of no louvers, 45° and vertical louvers have about the same average. Only the horizontal position is higher. A possible explanation is that the air is guided by the horizontal position of the louvers to go inside, but it might also be a large deviation due to changing outside wind velocities.

An assumption could be that when the louvers are completely closed, the air cannot come in well, so the velocities would be lower. But this cannot be concluded from the data.

The standard deviation is also calculated in Table 5 for the averages of each of the 4 windows, for every angle of louvers. What is noticeable is that the standard deviation for completely closed louvers is smaller. So the air speeds might be more constant when the louvers are in the closed position.

Open and closed door To see the influence of the opening of the door on the ventilation rate, only windows 1 and 3 were opened in room G104. The difference in air velocity in the windows was examined. The angle of the louvers was 45° in the situation of the open and closed door. The average air velocity with opened door was 1,5 m/s and with closed door 0,44 m/s (see Table 6). These values show that the velocity in this situation was significantly larger when the door was opened compared to the closed situation.

36

2.5 Thermal comfort, Air quality and velocity Table 6: Difference for velocities between open and closed door for G104

Door is

Nr.1 min (m/s)

Nr. 1 (m/s)

Open Closed

0,2 0,1

2,95 0,55

max Nr. 3 (m/s)

min Nr. 3 (m/s)

0,31 0,25

2,1 0,85

max Average both windows (m/s) 1,5 0,44

Refreshment rate The openings of the windows were about 8 cm wide, but because there is also air coming from the sides, the width of the opening is put at 10cm wide. The total window length is 1,48 cm.

When assuming that in most conditions at least 2 windows are open and the door is closed, the average velocity is 0,44m/s in the window. For two windows this would give the following calculation: 2 windows * 0,1m * 1,48m * 0,44m/s = 0,1302 m3/s Æ 468,9 m3/h The room is 7,7m*7m*2,85m = 153,6m3. This means that there is a refreshment rate of at least 3h-1.

When the door is opened this would be higher.

Velocity of old sunshade system (W107) The next measurements in room W107 were done on 6-10-2012. This room has the old sunshade system with fabric rollers. This room is bigger, with five columns of windows instead of four. But the windows that were chosen for the ventilation measurements had the same placement (and numbering in Figure 35) as the G104 room. The average velocity on that day between 08:00 and 16:00 was 2,3m/s, which is almost the half of the velocity at the day that G104 was measured.

Figure 35: Inside view or room W107 towards the outer façade

Different sunshade positions The difference of W107 with G104, is that the old sunshading system only has one position when it is down. All four windows were left open as well as the door. The specific measurements for each window can be seen in Appendix C, Table C- 3 and Table C- 5. Also the averages with standard deviation of all values per window have been noted inTable 7. There seems to be no large difference between louver positions, but again no real conclusions can be made as the difference in velocity between the sunshade positions is smaller than the measurement error. Not enough measurements were made and not accurate enough for a clear conclusion.

Table 7: Velocities for W107 for different sunshade positions

Sunshade position

Average velocity window1

Average velocity window2

Average velocity window 3

Average velocity window 4

Sunshade up Sunshade down

0,51 0,75

0,37 0,34

0,22 0,29

0,31 0,46

37

Average velocity all windows (m/s) 0,35±0,11 0,46±0,18

2. 5 Thermal comfort, Air quality and velocity Open and closed door Also for W107 measurements were made to look at the difference between open and closed door, with the sunshading down and windows 1 and 3 opened (see Appendix C, Table C- 4 for measurement values). The average velocity for opened door was 0,42 m/s and 0,54m/s for a closed door.

The difference between the door opened and closed does not seem very large in this room. This might be because the doors and windows in classrooms adjoining to the hallway were not open at that time, which makes cross-ventilation less effective.

Datalogger analysis To see the influence of the ventilation rate on the thermal comfort and air quality in the room, it has to be correlated to the data of the loggers. To be able to connect the ventilation rate to the results of the dataloggers, the longitudinal questionnaire was used. This gave information about the windows and doors that were opened during certain hours.

First ventilation values need to be given to different window and door situations. This was done globally, and with the help of the values that were measured in W107 and G104.

We assume a velocity of 0,5 m/s per window, which doubles when the door is opened. With one window open this would mean a refreshment rate of 1,5h-1. With all doors and windows closed, we assume that there is at least a refreshment rate of 0,5h-1 due to infiltration. We assume that a refreshment rate above 10h-1 is not realistic. See Appendix C, Table C- 6, for the exact used refreshment rates.

With the help of the longitudinal questionnaire (which said how many windows and doors were opened at certain times), the ventilation rates could be correlated against the room temperature for week 39 (See Appendix B, Figure B- 3 for complete graph). In Figure 36 one day is enlarged to see the effect of the refreshment rate better.

The gray lines in the graph show the moments when there are new students coming into the classrooms. It is evident that at some class changes, often the temperature gives a drop of at least 0,5째C. This is probably because the doors are opened, which increases the refreshment rate substantially. Also there is not a heat load in the room for a few minutes. With higher refreshment rates the temperature seems to rise slower than when the refreshment rate is lower.

Ventilation rates R209, Monday week 39

10

Room temperature (째C)

22,0 20,0

8

18,0 6

16,0 14,0

4

12,0 2

10,0

Refreshment rate in volume/hour

12 24,0

0

8,0 8:00

14:00

Ventilation rate

Lesson turn

Outside temperature

Room temperature

Figure 36: Ventilation rates R209 with room temperature for week 39, when the ventilation rate is unknown it is 0 38

2.5 Thermal comfort, Air quality and velocity

Maximum velocity Important for the thermal comfort is that the velocity is not too high, as has been told in the requirements for thermal comfort in the beginning of chapter 1. The maximum mean air velocity in summer should be 0.24m/s, and 0.21m/s in the winter (NEN-EN-ISO 7730, 2005).

For G104 and W107 hand measurements were made for the air velocity in five points in the room, at least half a meter from the window at around 1.4 meter height. Two windows were opened in these conditions. None of these values exceed 0,2m/s, but it should be noted that these are average values so the maximum values might exceed 0,2m/s.

The survey showed that almost 60% of the students suffer from draughts at some point. At the window itself the velocity can reach up to 2m/s, as can be seen in Table 5, which exceeds the requirements. Also when more than 2 windows are opened, the velocities might become too high, also for people further from the window.

Discussion There were not enough measurements made to make clear conclusions. There is a good possibility that the air velocities are lower when the louvers are completely closed in G104, but more precise measurements need to be made for that.

For this research the maximum and minimum was noted, from which the average could be calculated. It can be seen in Figure 37 that the spread of the measured values is very large, because only the maximum and minimum at one point is measured. It is for example better to make a weighted average of the velocity by measuring the velocity after a certain time interval more times to get the weighted average.

4

Velocity measurements G104

3,5 Velocity (m/s)

3 2,5 Maximum

2

Minimum

1,5

Average

1 0,5 0 No louvers

Horizontal

45 째

Vertical

Figure 37: Maximum and minimum measured velocities for windows 1 to 4, with the averages of all values

39

2. 6 Thermal comfort, Capsol

2.6 Simulations in Capsol Aim of the thermal simulations is to verify some of the conclusions made by that the analysis of the thermal measurements (see chapter 2.4.2 Analysis method of the thermal measurement), as well as to compare the efficiency of the old and new sun shading.

Initially the rooms in Capsol will be simulated under the very same conditions that the measurements were made. This way the model can be validated by comparing the values of the simulation with the true measurement form the data loggers. Secondly, the temperatures during the whole year will be simulated to see how much the indoor temperatures exceed the wanted values.

In general, the main target of the research is the evaluation of the different effects on the thermal comfort of the rooms caused by the old and new sun shade system, in classrooms with different orientation and geometric properties (see chapter 1.3 Research question). Therefore, all the rooms will be simulated, G104, R203, R205 and R209.

2.6.1 Calibration method The valid recorded temperature data for all classrooms are from 21/09/12 until 06/10/12. Thus, the calibration of the simulation model will be made for week 39 (Sat 22/09-Fri 28/09) and week 40 (Sat 29/09- Fri 05/10).

The most crucial dates in calibrating the Capsol model, were the weekends of week 39 (22/0923/09) and week 40 (29/09 -30/09). During these days, unpredictable factors that affect the temperature of the room, like the internal heat load from the artificial light are nil. Additionally, the ventilation and the position of the shading system cannot change under the influence of the users.

Therefore, having all these conditions known (or stable), it was possible to conclude some concrete results for unknown parameters like the thermal mass, the insulation and the ZTA & Uvalues of the sun shade systems.

Presentation method of the graphs Most of the following presented graphs are not the direct graphs that Capsol renders. There are two reasons behind that choice. Firstly, for greater flexibly in comparing data from multiple simulations with different parameters. Secondly, for minimizing the 'jigging' effect in the Capsol graphs. Manipulators such as dynamic ventilation cause steep fluctuation of the temperature, which is relative unrealistic, making at the same time difficult the clear overview of the graph. In order to 'soften' the temperature curve the alphanumeric output of the mean temperature per hour has been transferred in excel. The visual reliability of the re-plotted graphs is presented in Figure 38 and Figure 39.

Figure 38: Temperature graph of G104 rendered in Capsol.

40

2.6 Thermal comfort, Capsol

G104 no sun shade (12-14 June) 35 30

T[°C]

25 20 15 T_out G104_Jun_no sun shade

10

R203_Jun_no sun shade R209_Jun_no sun shade

5 12-jun

13-jun

14-jun

15-jun

Figure 39: The same temperature presented in Figure 38, but plotted in Excel using alphanumeric values from Capsol (mean temperatures per hour).

2.6.2 Geometry Input The CAD drawings of the school provide useful information for the dimensions of some structural elements that consist the thermal mass of the rooms. Based on that, the side walls proved to have been made of a double layer of 10 cm brick. However, the thickness of the concrete slabs as well as the insulation in external walls, the floor or the roof remained unknown. After some calculation experiments, focusing mainly on weekends as explained in chapter 2.6.1 Calibration method', the insulation in the roof and the floor slab proved to a very influential parameter. For example without insulation in the exposed floor in G104 and in the roof of R203, the indoor temperature couldn’t reach similar values with the ones from the data loggers (see Figure 40).

R203 Week 39 (22-24Sep)

22

1000 900

20

800 700

T [°C]

18

600 500

16

400 14

300 200

12

18:00

12:00

6:00

24-9 mon

18:00

12:00

6:00

23-9 sun

18:00

12:00

6:00

10

22-9 sat

100

T(out)

R203_dataloggers

R203_Capsol_f

R203_Capsol_no roof insulation

R203_Capsol_no brick insulation

Q global [W/m2]

0

sensor west [W/m2]

Figure 40: Comparison of the indoor temperature curve in R203 under the influence of different assumptions about the insulation of the room.

41

2. 6 Thermal comfort, Capsol Thus, the final conclusion for the thermal mass and the insulation were: • • • • •

d (concrete slab): 240mm Rc (external brick wall): 1.1 m2K/W, with d(ext. polysterine): 30mm Rc(concrete slab-G104):1.8 m2K/W, with d(ext. polysterine): 60mm Rc (roof-R203,R209):1,8 m2K/W, with d(ext. polysterine)=60mm no insulation in the facade parapet

The geometry of the external façades has been analyzed in three 'wall' types; glass, frame, and parapet. A similar analysis has been made for the interior façades; the only exception is R203 in which the interior façade consists only of a single brick wall. In general, the room R205 has many differences in the modeling compared to the other rooms. For more information about the geometry input see Appendix B: Figure B- 12 -Figure B- 13 and for the materials Figure B- 16-Figure B- 21.

2.6.3 Simulation Function references Climate conditions In order to compare the real temperatures from the data loggers with the Capsol simulation, the first step was the creation of the existing outdoor conditions for September 2012 in Roosendaal (week39 and 40).

As it has been already explained, in the final temperature reference, data from the control sensor of the louvers (between 29/09 and 12/10) have been combined with the temperatures recorded from Woensdrecht in 2011-12. Additionally, the horizontal global solar radiation was also taken from the same meteorological station, while the conversion to direct and diffused radiation was made with the method of derivation as described by Velds (Velds, 1989). (See Appendix B, Figure B- 5 - Figure B- 8 for more information about the climate function references used for the calibration of the Capsol simulation.)

Internal heat loads The internal heat load reference consists of three values: • Qi of an occupied room during the lessons • Qi of a non occupied room during the working hours of the school • Qi of a non occupied room when the school is closed Qi of an occupied room This parameter is the most crucial, as it is the main internal heat load in a room, it consists of the heat load due to occupancy and the heat gain from the artificial lighting. However, both these factors are not constant during the day, they change from one hour to the other, and they are different for every room. So, all the rooms have their own heat load function references that 'follow' the time schedule of the courses (see Figure 41 and Figure 42, as a comparison of the different function references between G104 and R203 only for week 40).

It was impossible to calculate the exact amount of pupils during every lesson for all the days in week 39 and 40. Instead of that, based on information from the tutor's logbook, it was possible to estimate an average occupancy for all the classrooms. Therefore, during the courses, an assumption for an average amount of 27 persons has been made.

Concerning the artificial lighting, in every classroom there are 12 fluorescent lamps, so, the maximum heat gain from all them is 420 W (35W x12). However, the artificial lighting isn't used all the time, especially during the moths of September and October where the daylight levels are still high. So, it was made a simplification of using 50% of the maximum heat gain from the lamps.

Additionally, during the breaks and the hours that the classrooms are free of lessons, a minimum heat load of 140 W remains. Finally, heat load from other equipment wasn't taken into 42

2.6 Thermal comfort, Capsol consideration, as it is instantaneous, for example it was observed that the TV-screens weren't used during all the time of a course.

Heat load from average occupancy: Heat load from the luminaries: Total average heat load:

Qp= 28 x 75 W = 2100 W Ql= 420 x 50%=210 W Qi(during courses)= Qp + Ql = 2310 W

Qi (when the school is closed) When the school is closed there is no internal heat load in the rooms, at least for the examined period of week 39 and 40.

The reliability of the above values has been verified through calculation experiments in Capsol.

The initial estimation for the internal heat load was slightly bigger, due to higher influence of the artificial lighting. However, the value of 2310 W, for an occupied room, it was giving the closest output to the real measurements.

The final function references for the Internal heat loads have been designed for five weeks because of a needed accuracy during the warm up period that precedes of week 39 and 40. The function references have been made with values per minute. Thus, in the function references week 39 starts at minute 3020, while week 40, at 40320.

(For a general overview of the different heat load references in all the rooms see Appendix B, Figure B- 22- Figure B- 27).

Figure 41: Function reference of the internal heat load in G104 for week 40.

43

2. 6 Thermal comfort, Capsol

Figure 42: Function reference of the internal heat load in R209 during week40.

Ventilation rates In general, the Gertrudis school is a free running building, so the ventilation, in most of the rooms depends on the presence of the user. Similarly to the internal heat load, the function reference of ventilation is unique for every classroom following the course schedule.

The design of this function reference is based on four values: • Ventilation rate during the lessons (nroom) • Ventilation rate during the breaks (nbreak) • Ventilation rate when the occupancy is nil during the working hours (nroom_02) • Ventilation rate when the school is closed (ninfiltration)

Ventilation rate during the lessons During the different lesson hours the ventilation rate changes due to the influence of the users. It would have been impossible to estimate these changes with precision. Thus, an average ventilation rate based on information from the tutor's logbook, considered the most reasonable choice. In most of the cases during the lessons, two windows are opened with the door closed.

These conditions provide a refreshment rate close to n=3 (see chapter 2.5.3 Velocity measurement results) despite the fact that for healthier indoor environment a rate of 5 or even 6 would had been preferable.

Additionally, when the indoor temperature is really high, it is assumed that the condition of having only two windows open will change. Thus, when the indoor temperature exceeds 25oC the room is provided with 750m3/h of fresh air instead of 450m3/h (n=3). This last dynamic parameter is not integrated in the ventilation reference, it is regulated by the controls of the Capsol simulation (see Appendix B, Figure B- 14 and Figure B- 15).

Ventilation rate during the breaks During the breaks the air velocity increases significantly due to cross ventilation caused by the door which remains opened. In chapter 2.5.3 it has been analyzed that a cross ventilation can create high air velocity, resulting in maximum ventilation rate close to 9. However, this velocity is highly depending on unstable parameters, and a choice for a ventilation rate of n=5 considered more realistic.

44

2.6 Thermal comfort, Capsol Finally, the ventilation rate when the occupancy is nil during the working hours, has been estimated to n=0.8, while, the calculation of the air infiltration from the cracks of the faรงade determine a ventilation rate close to 0.2.

Figure 43: Ventilation reference for G104, weeks 36-40.

Figure 44: Ventilation reference of G104, week 40 .

45

2. 6 Thermal comfort, Capsol

2.6.4 Control of the sun shading The specifications of the sun shade system were mainly verified through the calibration process explained in chapter 2.6.1 Calibration method. The conclusions for the physical properties of the faรงade and the sun shading elements were: Single glass (6mm): ZTA (g-value)=0.85 and U-value=5.67W/m2K Fabric rollers: ZTA (g-value)=0.2 and U-value=5.48 W/m2K Louvers(a): ZTA (g-value) =0.1 and U-value=4.79 W/m2K Figure 45, shows an example with different g-values for the fabric rollers, proving that a value of 0.2 is more accurate than 0.24.

For simulating in Capsol the central control of the louvers and the rollers, three control sensors have been made. The three sensors calculate the global solar radiation in a vertical plane with east, west and south orientation identically to the orientation of the facades in rooms G104, R205 and R209. The threshold for activating both louvers and fabric rollers was estimated to 150W of global solar radiation in the vertical plane of every sensor. In all the plotted graphs, it is presented the global solar radiation in the sensors compared to the global radiation in a horizontal plane that was used as a function reference. These values are quite different, thus , the activation of the sun shading does not derive directly from the levels of horizontal global radiation.

However, the louvers have the ability to adjust their g-value when they are totally closed. In the simulation model, above 250W of global solar radiation (on the vertical plane of the sensor) the louvers decrease their ZTA to 0.06. (see Appendix B, Figure B- 14 and Figure B- 19). In Figure 46, the effect of activating the louvers in 150W is displayed, as well as the improvement in the calibration if the ZTA value is decreased to 0.06 above 250W. Thus, this ZTA value simulates the ability of the louvers to almost totally block the incoming solar radiation if this is concerned necessary.

The effect of the interior curtains in R205 Special mention has to be done for the shading of R205, not for the external system but the existence of heavy internal curtains and the way that the users controlled them. Initially, R205 had the biggest deviations of indoor temperatures from the data loggers. While in all the other rooms (R203, R205, G104) the simulation seemed to be quite close to reality. In R205 the predicted temperature curve were constantly displaced upwards by 1 or even to 2 degrees (see Figure 53and Figure 54). A given explanation was that, the 'heavy' interior curtains in R205 were closed by the users, after the working hours, affecting drastically the u-value of the facade.

Thus, the biggest change in the calibration of the final model for R205 was that during the night there are closed curtains in the room, changing the U-value of the facade from 5.67W/m2K to 2.93 W/m2K (see that material in Appendix B, Figure B- 21). In the early morning hours they are replaced by a glass facade without interior curtains, so, during the courses the shading works with the same way like in the other rooms (see the controls in R205 in Appendix B, Figure B- 15). Figure 53 and Figure 54 show the difference in simulations with and without the influence of the heat losses from the interior curtains).

46

2.6 Thermal comfort, Capsol

R209 Week 38 (15-17 Sep) 1000

24

900

22

T [째C]

800 20

700

18

600 500

16

400

14

300 200

12

100

10 18:00

12:00

6:00

17-9 mon

18:00

12:00

6:00

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18:00

12:00

6:00

15-9 sat

0

T(out)

R209_dataloggers

R209_Capsol_roller g-value:0.2

R209_Capsol_roller g-value:0.24

Q global [W/m2]

sensor east [W/m2]

Figure 45: Comparison of the indoor temperature curve in R209 under the influence of different ZTA values of the fabric rollers.

G104 Week 39 (22-24Sep) 22

1000 900

20

800

T [째C]

18

700 600

16

500 14

400 300

12

200 10

T(out)

G104_ dataloggers

G104_Capsol_ Qd>150W ZTA: 0.1, Gd>250W ZTA;0.06

G104_Capsol_ Qd>150W ZTA: 0.1

Q global [W/m2]

sensor west [W/m2]

18:00

12:00

6:00

24-9 mon

18:00

12:00

6:00

23-9 sun

18:00

12:00

6:00

22-9 sat

8

100 0

Figure 46: Comparison of the indoor temperature curve in G104 under the influence of different ZTA values activation sensitivity in direst solar radiation.

47

2. 6 Thermal comfort, Capsol

2.6.5 Calibration results The Table 8 shows the average indoor Table 8: Average indoor temperature in week39-40, between temperature between Capsol simulations 08:00 until 16:00 per day. and data loggers in weeks 39 and 40. The Tavg(째C) R209 R203 G104 R205 average temperatures have been 08:00-16:00 calculated between 08:00 and 16:00. Such loggers 20.1 20.0 20.1 20.6 a comparison indicates that the general Capsol 19.5 19.4 19.5 20.1 accuracy of the simulation during the working hours is close to a deviation of 0.5o C. However, for a better overview, a per day analysis has been made (see Figure 47-Figure 54). In general, despite the occasional bigger deviations, the credibility of the model appears sufficient for comparing the different sun shading systems. (Examples of temperature graphs from the calibration of the models directly from Capsol, without using the method of hourly mean temperatures, can be seen in Appendix B, Figure B- 34Figure B- 35.)

Critical analysis of the calibration results In rooms G104 and R203 the comparison between the dataloggers and the final Capsol simulation, shows small deviations which do not exceed 0.5o C. The biggest problem though is a shift of the temperature curve in the x axis (time). This problem is quite intense during the weekends, in a way that the room warms up faster in the simulation.

Uncertainties in the internal heat load, the ventilation rates, and the position of sunscreens are the main reasons behind bigger deviations. For example in G104 on 29/09 (see Figure 48) and in R203 on 04/10 (see Figure 50) there is an unexpected rise of the temperature that does not keep up with the simulation. However, the controller of the louvers showed that the system didn't work properly, or it was over written by the users.

Additionally, in G104 on 24/10 (see Figure 48) there is a significant down peak in the indoor temperature during the night and early morning hours; this can only be explained by the influence of a higher ventilation rate due to open windows. Similar deviations during the early morning hours, but in smaller degree, appear also in G104 on26/09 and 03/10, as well as in R203 on 03/10.

In R209, the biggest problem was that the calibration didn't match the results from data loggers for two of the critical days during weekends. On 30/09 (see Figure 50) there is a shift of the temperature curve by 1 degree, while during the night on 24 /09 (see Figure 51) there is a strange down peak that the simulation does not predict.

In R205, after the problem with the interior curtains was noticed the simulations proved quite accurate during the weekends and the weekdays as well.

48

2.6 Thermal comfort, Capsol

23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

700 600 500 400 300 200

T(out)

G104_ dataloggers

G104_Capsol_f

18:00

0 12:00

6:00

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28-9 fri

6:00

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18:00

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22-9 sat

T [째C]

G104 (west facade) Week 39(22-28 Sep)

sensor west [W/m2]

Figure 47: G104, week 39. Comparison between Capsol simulation and recorded temperatures from data loggers.

23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

700 600 500 400 300 200 100

T(out)

G104_ dataloggers

G104_Capsol_f

Q global [W/m2]

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18:00

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0 29-9 sat

T [째C]

G104 (west facade) Week 40 (29 Sep-05 Oct)

sensor west [W/m2]

Figure 48: G104, week 40. Comparison between Capsol simulation and recorded temperatures from data loggers.

49

2. 6 Thermal comfort, Capsol

22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

700 600 500 400 300 200

T(out)

R203_Capsol_f

18:00

6:00

12:00

18:00

Q global [W/m2]

28-9 fri

6:00

12:00

18:00

27-9 thu

12:00

6:00

26-9 wed

18:00

6:00

12:00

18:00

R203_dataloggers

25-9 tu

6:00

12:00

24-9 mon

18:00

12:00

6:00

18:00

23-9 sun

6:00

12:00

100

22-9 sat

T [째C]

R203 (west facade) Week 40 (22-28 Sep)

0

sensor west [W/m2]

Figure 49: R203, week 39. Comparison between Capsol simulation and recorded temperatures from data loggers.

700

24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

600 500 400 300 200

T(out)

R203_dataloggers

R203_Capsol_f

18:00

6:00

12:00

18:00

5-10 fri

6:00

Q global [W/m2]

12:00

4-10 thu

18:00

12:00

6:00

3-10 wed

18:00

6:00

12:00

18:00

2-10 tu

12:00

6:00

1-10 mon

18:00

12:00

6:00

18:00

30-9 sun

6:00

12:00

100

29-9 sat

T [째C]

R203 (west facade) Week 40 (29 Sep-05 Oct)

0

sensor west [W/m2]

Figure 50: R203, week 40. Comparison between Capsol simulation and recorded temperatures from data loggers.

50

2.6 Thermal comfort, Capsol

22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

Week 39(22-28 Sep) 700 600 500 400 300 200

R209_dataloggers

R209_Capsol_f

Q global [W/m2]

sensor west [W/m2]

sensor east [W/m2]

0

18:00

6:00

12:00

18:00

T(out)

28-9 fri

6:00

12:00

18:00

27-9 thu

12:00

6:00

26-9 wed

18:00

6:00

12:00

18:00

25-9 tu

6:00

12:00

24-9 mon

18:00

12:00

6:00

18:00

23-9 sun

6:00

12:00

100

22-9 sat

T [째C]

R209 (east facade)

Figure 51: R209, week 39. Comparison between Capsol simulation and recorded temperatures from data loggers.

23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

Week 40 (29 Sep-05 Oct) 700 600 500 400 300 200

T(out)

R209_dataloggers

R209_Capsol_f

Q global [W/m2]

sensor west [W/m2]

sensor east [W/m2]

18:00

6:00

12:00

18:00

5-10 fri

12:00

6:00

4-10 thu

18:00

12:00

6:00

3-10 wed

18:00

6:00

12:00

18:00

2-10 tu

12:00

6:00

1-10 mon

18:00

6:00

12:00

30-9 sun

18:00

12:00

6:00

100

29-9 sat

T [째C]

R209 (east facade)

0

Figure 52: R209, week 40. Comparison between Capsol simulation and recorded temperatures from data loggers.

51

2. 6 Thermal comfort, Capsol

700 600 500 400 300 200

T(out) R205_Capsol_without internal curtains sensor south [W/m2] sensor west [W/m2]

18:00

6:00

12:00

18:00

28-9 fri

12:00

6:00

18:00

27-9 thu

6:00

12:00

26-9 wed

18:00

6:00

12:00

18:00

25-9 tu

12:00

6:00

18:00

24-9 mon

6:00

12:00

23-9 sun

18:00

6:00

12:00

100

22-9 sat

T [째C]

R205 (west & south facade) Week 39 (22-28 Sep) 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

0

R205_dataloggers R205_Capsol_with internal curtains during the night Q global [W/m2]

Figure 53: R205, week 39. Comparison between Capsol simulation and recorded temperatures from data loggers.

700 600 500 400 300 200

18:00

6:00

12:00

5-10 fri

18:00

12:00

6:00

18:00

4-10 thu

12:00

6:00

3-10 wed

18:00

6:00

12:00

2-10 tu

18:00

12:00

6:00

18:00

1-10 mon

12:00

6:00

30-9 sun

18:00

6:00

12:00

100

29-9 sat

T [째C]

R205 (west & south facade) Week 40 (29 Sep-05 Oct) 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7

T(out)

R205_dataloggers

R205_Capsol_without internal curtains

R205_Capsol_with internal curtains during the night

sensor south [W/m2]

Q global [W/m2]

0

sensor west [W/m2]

Figure 54: R205, week 40. Comparison between Capsol simulation and recorded temperatures from data loggers.

52

2.6 Thermal comfort, Capsol

2.6.6 Comparison between fabric rollers and louvers In that final part of the simulations as function references for outside temperature and solar radiation have been used data from De Bilt in 1964 (average climate year for the Netherlands). All the other function references (internal heat loads, ventilation rates etc) are similar to the ones explained in the previous chapters, the only difference is that they simulate average conditions which are the same for all the rooms (see Appendix B, Figure B- 36-Figure B- 37). Especially, for R205, the influence of the interior curtains has not been taken into consideration in order to compare the results under the same boundary conditions.

The evaluation period for the two sun shade systems consists of the five warmest months of the season; May, June, July, August and September. Even though not many lessons take place during July and August it was necessary for the completeness of the research to present the data for the whole summer season, however, special attention will be given for May, June and September.

According to NEN-EN-ISO 7730, the temperature criteria for a classroom (category C), is 24,5°± 2,5°C in the summer, and 22,0°C ± 3°C in the winter. Therefore, the critical parameter is the amount of hours that the indoor temperature exceeds 26o C. Table 9: Amount of hours that the indoor temperature exceeds 26oC (for the whole day).

May

June

July

Aug

Sep

Total

G104 Louvers

1,1

8,6

25,4

1,4

0,2

36,7

G104 Rollers

4,4

15,5

44,5

3,5

2,1

70,0

117,5

195,7

257

118

42,4

730,6

2,7

13,6

32,8

1,3

0,0

50,4

G104 No sunshade R203 Louvers R203 Rollers

6,9

21,4

57,6

4,2

1,5

91,6

R203 No sunshade

132,4

216,9

281,6

120,2

33,8

784,9

R209 Louvers

39,2

63,1

99,2

14,9

2,2

218,6

R209 Rollers

45,7

79,3

112,8

19,3

2,7

259,8

R209 No sunshade

137

230,8

263,3

64

20,3

715,4

R205 Louvers

3,9

14,7

43

1,5

0

63,1

R205 Rollers

16,5

31

70,9

8,5

2

128,9

R205 No sunshade

202,6

285,6

323,7

88

81,9

981,8

Table 10: Amount of hours that the indoor temperature exceeds 26oC (between 08:00-16:00).

May

June

July

Aug

Sep

Total

G104 Louvers

1,1

8,5

21,9

1,4

0,2

33,1

G104 Rollers

4,4

12,3

29,1

3,5

2,1

51,4

G104 No sunshade

54,0

72,2

98,2

51,0

24,7

300,1

R203 Louvers

2,7

10,7

23,9

1,3

0,0

38,6

R203 Rollers

6,8

13,3

31,5

4,2

1,5

57,3

R203 No sunshade

53,7

71,6

96,9

46,1

20,1

288,4

R209 Louvers

29,7

36,2

58,6

14,5

2,2

141,2

R209 Rollers

31,7

41,0

60,3

17,1

2,7

152,8

R209 No sunshade

63,4

91,9

107,8

46,5

18,9

328,5

R205 Louvers

3,9

10,9

27,5

1,5

0,0

43,8

R205 Rollers

10,9

17,1

37,8

1,5

2,0

69,3

R205 No sunshade

86,7

110,1

121,3

203,4

43,6

565,1

53

2. 6 Thermal comfort, Capsol Table 11: Average room temperatures between 08:00 and 16:00.

May

June

July

Aug

Sep

19,8

22,8

23,0

22,9

21,3

20,6

23,3

23,4

23,3

21,7

G104 No sunshade[ C]

23,4

25,5

25,8

25,1

23,5

R203 Louvers [oC]

20,1

22,9

23,2

22,8

21,1

20,7

23,4

23,5

23,3

21,5

R203 No sunshade [ C]

23,4

25,4

23,5

21,5

23,2

R209 Louvers [oC]

21,9

24,6

24,8

24,5

21,8

22,2

24,6

24,3

23,1

21,9

R209 No sunshade [ C]

23,6

25,8

25,1

23,8

23,7

R205 Louvers [oC]

20,1

22,6

23,0

22,6

20,8

20,8

23,2

23,4

23,1

21,5

24,1

25,9

25,8

25,2

24,3

o

G104 Louvers [ C] o

G104 Rollers [ C] o

o

R203 Rollers [ C] o

o

R209 Rollers [ C] o

o

R205 Rollers [ C] o

R205 No sunshade [ C]

Table 12: Time that room temperature exceeds 26oC, as percentage of the total occupied time.

G104 Louvers

May

June

July

Aug

Sep

Total

0,4%

3,5%

8,8%

0,6%

0,1%

2,7%

G104 Rollers

1,8%

5,1%

11,7%

1,4%

0,9%

4,2%

G104 No sunshade

21,8%

30,1%

39,6%

20,6%

10,3%

24,5%

R203 Louvers

1,1%

4,5%

9,6%

0,5%

0,0%

3,2%

R203 Rollers

2,7%

5,5%

12,7%

1,7%

0,6%

4,7%

R203 No sunshade

21,7%

29,8%

39,1%

18,6%

8,4%

23,6%

R209 Louvers

12,0%

15,1%

23,6%

5,8%

0,9%

11,5%

R209 Rollers

12,8%

17,1%

24,3%

6,9%

1,1%

12,5%

R209 No sunshade

25,6%

38,3%

43,5%

18,8%

7,9%

26,8%

R205 Louvers

1,6%

4,5%

11,1%

0,6%

0,0%

3,6%

R205 Rollers

4,4%

7,1%

15,2%

0,6%

0,8%

5,7%

R205 No sunshade

35,0%

45,9%

48,9%

82,0%

18,2%

46,2%

General evaluation of the two shading systems For a general comparison it was necessary to present the amount of hours that exceed 26oC throughout the whole day (seeTable 9). However, the following conclusions are based on Table 10 and Table 12 which focus only on the working hours of the school. (Analytically, the temperature curves from the simulations for the comparison of the different sun shading systems are presented in the Appendix B, Figure B- 38 - Figure B- 43.)

In general the differences between the two systems derive as consequence of the ZTA (g-value) and the U-value (Table 13) with the g-value being more influential. The U-values are relatively close as both systems are external and do not prevent significant heat losses, especially for the fabric rollers the U-value (5.48 W/m2K) is almost identical to one of a facade without any sun shading (5.67 W/m2K).

Table 13: ZTA and U-value of the two different sun shading systems, as well as without sun shade at all.

Sun shade

ZTA (g-value)

U-value

Louvers

0.1 [0.06, Qsolar radiation sensor>250W]

4.79 W/m2K

Fabric rollers

0.2

5.48 W/m2K

No sun shading

0.85

5.67 W/m2K

54

2.6 Thermal comfort, Capsol For G104 and R203 is clear that both systems prevent most of the unwanted solar gain. Table 12 shows that for a typical room with western facade both systems limit the rise of the temperature above 26oC below 10% of the total occupant time (with an exception for July). However, the louvers can regulate the indoor temperature in an even more efficient way. So, using louvers during the warmest months of the school year the amount of hours, between 08:00 -16:00, that exceeds 26oC, drops even more to 2.7% in G104 and to 3.2% in R203 (see Table 12).

In R205 it is obvious that the new shading is more effective than the old one, thus, using fabric rollers the percentage of hours exceeding 26oC is relatively high (5.7%), while the louvers drop it to 3.6%(see Table 12).

In R209, there is also a small improvement by using louvers, however both systems fail to regulate the indoor temperature in a way that it does not exceed 26oC for less than 10% of the total occupant time, especially for May and June something which does not happen in the other rooms (see Table 12). Thus, it seems that in the rooms with east orientation the new sun shading system does not make significant difference. Figure 55 which focus only for the most three crucial months (May, June, September) summarises that conclusion. A possible explanation for that reason is given in the following chapter.

Hours above 26째C 200

150

100

50

0 May

June

Sep

Total

G104 Louvers

G104 Rollers

G104 No sunshade

R203 Louvers

R203 Rollers

R203 No sunshade

R209 Louvers

R209 Rollers

R209 No sunshade

R205 Louvers

R205 Rollers

R205 No sunshade

Figure 55: Amount of hours that the indoor temperature exceeds 26oC. The calculation has been made between 08:00-16:00 and the "total" refers only for these three months; May, June and September.

2.6.7 Thermal behaviour of all the rooms Aim of this chapter is to evaluate further some of the preliminary conclusions made after the analysis of the thermal measurements (see chapter2.4.3 Thermal measurement results). The Capsol simulations focuses on a wider period, giving more information about aspects of the thermal behaviour of the rooms that weren't clear during the relative limited period of week 39 and 40. The conclusions in this chapter derive from the analysis of the simulation results but only for the warmest months. Again it is necessary to highlight that in this chapter the effect of the interior curtains in R205 hasn't been considered.

55

2. 6 Thermal comfort, Capsol

West rooms with one facade For R203 and G104 the Capsol simulations showed that they have similar thermal behaviour. Both rooms have large exposed surfaces; G104 has its floor exposed to the outside conditions, while R203 has an exposed wall and a roof. Despite the larger exposed surface, R203 has higher temperatures but not that much. Table 9 reveals that under all the different shading conditions, the hours that temperature in R203 exceeds 26oC are always more compared to G104. Similar conclusion derives from the average temperatures in Table 11.

East rooms with one facade In R209 (eastern facade) the simulation showed that this room reaches higher temperatures earlier than the other rooms, something quite logical due to the orientation (the temperature fluctuation of R209 that verifies this conclusion can be observed in the Appendix B, Figure B- 41- Figure B- 43).

As an example, Figure 56 shows that under different shading concepts it is clear that around 12:00 the temperature in R209 is much higher compared to rooms with west orientation. However, in the analysis of the measurements (chapter 2.4.3 Thermal measurement results) it wasn't clear that the peak temperature of R209 is not always around 12:00, this happens only in colder months. A closer look on Figure 56 reveals that during June the outside conditions are so warm that the east rooms continue to warm up due to the influence of the internal heat load from the pupils. The fact that the internal heat load is the main 'heating' factor after 12:00, makes all the sunshading systems not effective enough. The heat removal becomes the main problem and by blocking unwanted solar radiation the problem cannot be solved.

Error! Reference source not found. depicts that phenomenon even thought it does not provide the necessary information to explain it. Thus, in September the amount of hours that exceed 26oC is bigger in R209 than in R203 and G104, but the outside conditions are not that warm to show the real size of the problem. Only, for May and June this becomes clear as the hours above 26oC dramatically increase to 29.7 in May and 36.2 in June, even with the more effective new sun shading (see Table 10).

Thus, the assumptions for R209 from the analysis of the dataloggers (week 39 - 40) are verified but in more dramatic way, as the simulations show that the thermal discomfort in east rooms will be even higher than it was initially predicted.

West rooms with two facades (second facade with south orientation) R205 is a quite different room due to the fact that it has one extra facade and at the same time bigger volume (approximately 200m3 instead of 150 m3). From one point of view, the extra facade means that the room will have higher indoor temperature from the other rooms. In a way this is verified under the conditions that all the rooms have no sunshading, in that case R205 is by far the warmest room.

On the other hand, the outcome is quite different under the influence of sun shading. An extra facade also means bigger heat losses, while, a bigger volume means smaller influence of the internal heat load. The Capsol simulations assume that the shading is not changed by the users, so its performance in blocking solar radiation is optimized. The conclusion is that between 08:00 and 16:00, with sunshading (whether this is louvers or fabric rollers) R205 is warmer than G104 and R203 but not from R209 (see Figure 55). Thus, when all rooms have a sun shade system that works under the same conditions, the east rooms have the highest temperatures.

Figure 56 shows the temperature curves for R203, R209 and R205 during the warmest period of June, under different shading concepts. The dashed lines represent the temperature of the rooms

56

2.6 Thermal comfort, Capsol with louvers, it clear that under this condition the average temperature in R209 is higher even if the peaks in R205 are bigger.

Figure 56: Comparison of the effect of the different sun shading systems on the indoor temperature of R203 and R209. The results are the warmest period of June (10 -20 of June De Bilt 1964).

2.6.8 Alternatives in the use of the new sunshade The conclusion that R205 won't be warmer than R209 with the use of sun screens it wasn't clear from the analysis of the dataloggers, during week39-40 (see chapter 2.4.3 Thermal measurement results). The thermal measurements in the school showed that the indoor temperature of R205 is higher from all the other rooms, even during the weekends, when the influence of the internal heat load is nil. Initially this result was attributed to the extra facade, however, this assumption proved not to be real and the reason was that the influence of the internal curtains in R205 hasn't been considered.

The observation that the increased temperature of R205 during week 39-40 was due to the closed indoor curtains during the night, it gave the motivation to test this 'mechanism' of minimizing the heat losses in other rooms. This is quite important because a problem that was observed from the analysis of the measurements (and verified with the calibration of the Capsol model) was that the western rooms have temperatures below the comfortable levels in the early morning hours. Thus, in that chapter we are going to explore how the user can use shading methods (externally or internally) in a more effective way, minimizing the heat losses and maximizing the solar gain whenever this is necessary.

57

2. 6 Thermal comfort, Capsol For that reason we run simulations with three different shading scenarios in G104, a typical room with west orientation. The aim was to see if it is possible to increase the room temperature in more comfortable levels, passively without using heating. The simulations took place in the second week of May (Climate conditions De Bilt, 1964), an interesting period just before the summer when the use of heating is not necessary.

The three simulation scenarios are: 1. The standard conditions, without using thick internal curtains, while the activation threshold of the louvers being at 150W of global radiation (on the surface of the sensor which is vertical and not horizontal).

2. Closed interior curtains only during the night, keeping the louvers with the same activation threshold as in the first scenario.

3. Closed interior curtains only during the night but also increasing the activation threshold of the shading to 250 W. The first aspect that we want to investigate is whether the sensor threshold at 150W is too strict for all the different outside conditions. In other words, whether the new shading system is centrally controlled in way that it is blocking solar radiation which could have been useful. The second aspect is to estimate the effect of closed internal curtains during the night.

1000

24 23 22 21 20 19 18 17 16 15 14 13 12 11

900 800 700 600 500 400 300 200 100 15-mei

14-mei

13-mei

12-mei

11-mei

10-mei

9-mei

8-mei

0 7-mei

T[oC]

G104 Capsol Simulations with different shading concepts (07-15 May)

without closed curtains during the night -louvers(sensor threshold at 150W) closed curtains during the night - louvers (sensor threshold at 150W) closed curtains during the night -louvers(sensor threshold at 250W) solar radiation of shading sensor (vertical plane with southwest orientation) [W/m2]

Figure 57: Capsol simulation in G104 with three different shading scenarios.

In Figure 57, the temperature fluctuation is plotted under the three scenarios. The first observation is that the interior curtains were able to increase the temperature by 1 degree. This verifies that the curtains are beneficial in the same way that was observed throughout the calibration of R205.

Previously presented graphs in Figure 53 and Figure 54 show similar results.

Another observation is that even with 250W as activation threshold, the room temperature never exceeds 23oC which mean that the control of the louvers should be investigated further and 58

3.1 Visual comfort, definitions should not stay stable for all the year. Maybe in June a threshold of 150W is necessary but in other colder periods, the solar gain is beneficial and a higher threshold would be more efficient.

As the problem with low temperatures is more intense during the early hours, another representation way is displayed in Figure 58. In that graph the mean indoor temperatures between 08:00-11:00 are presented, for the same period (7th -15th of May).

26 25 24 23 22 21 20 19 18 17 16 15 14

T(mean)09:00-11:00- without internal curtains - Louvers (sensor threshold at 150W) T(mean)09:00-11:00- closed internal curtains (during night) -Louvers (sensor threshold at 150W) T(mean)09:00-11:00- closed internal curtains (during night) -Louvers (sensor threshold at 250W)

15-mei

14-mei

13-mei

12-mei

11-mei

10-mei

9-mei

8-mei

T(mean)09:00-11:00- without internal curtains -Without using any sunshade 7-mei

T [째C]

G104 Capsol Simulations with different shading concepts (07-15 May) T (mean) Between 09:00-11:00

Figure 58: Average room temperature (G104) between 09:00-11:00 under the effect of different shading scenarios.

In general, Figure 58 shows that the role of the user can be important in regulating the thermal comfort in a smart way, in order to minimize the heat loses and maximize the beneficial solar gain.

If the louvers are activated at 150W of global radiation (on the sensor) then an important heat gain is lost. Thus, if there is no visual discomfort, during cold periods the users ought to manually control the louvers manually, adjusting them in a position that the solar gain is not blocked.

Also, the simulations reveal that the activation threshold of the louvers needs further investigation, as there are time periods that a higher threshold at 250W is thermally more effective.

The graph in Figure 57 proves this recommendation, as the temperature curve has been shifted up by 2 degrees but not above 23oC.

59

2.7 Thermal comfort, Conclusions

2.7Thermal comfort conclusions Before discussing the main research question, a brief overview of the sub questions is given. Some interesting conclusions and answers can be drawn from a comparison between R209 (old sun shading) and G104, R205, R203 (new system) for week 39 and week 40.

2.7.1 Effects of physical characteristics of the rooms on thermal comfort (sub questions) Since the sub research questions focus on the influence of physical room characteristics on the thermal comfort, it was important to exclude influences of internal gains from occupancy.

Therefore, mainly data from the weekends have been used.

1.1 What are the differences in the thermal comfort between a room on the top floor and a room on the first floor?

The analysis of the thermal measurements based on the dataloggers showed that G104 and R203 have similar temperature behavior. Compared to the other rooms, the temperatures in G104 and R203 drop to relatively low levels at night. This is because these rooms have a larger surface exposed to outside conditions. During the weekends, R203 is a bit warmer than G104.

The results also pointed out the big impact of internal gains due to occupancy during the weekdays. Significant more temperature fluctuations occurred in G104 and R203 than in R205 and R209, which could be explained by a more frequent use of the first two rooms.

Another interesting conclusion derived from the dataloggers was that during the week39, both G104 and R203 showed low start temperatures in the mornings, causing discomfort. Standards on thermal comfort, advising minimum temperatures above 19째C are not met.

The Capsol simulation verified that G104 and R203 have similar thermal behavior, and that despite the fact that R203 has a roof, their temperature differences are not that big, not only for September but also for warmer moths like June. However, R203 simulations results, under the same conditions as G104, are also slightly warmer.

1.2 What are the differences in the thermal comfort when comparing west orientated classrooms to east orientated classrooms?

The second subject of attention was the investigation of the differences in the thermal comfort between west (G104, R203 and R205) and east (R209) orientated classrooms.

From the analysis of the measurement in weeks 39 and 40, R209 showed peaks before 12:00, while, the other rooms only after 16:00. Thus, we initially assumed that R209 will have more comfort problems because the room is already warmed up before the lessons start, especially during more extreme conditions in summer. In winter this is an advantage, something that is confirmed by the fact that for week 39 and 40 all temperature standards are met.

Despite different orientations, G104, R203 and R209 showed similar average temperatures during the period of the measurements. However, the Capsol simulation made more clear the thermal behaviour of R209, proving that under the influence of sun screens, east rooms will be significantly warmer than the west orientated rooms.

In order to verify this conclusion another Capsol simulation was made for two identical rooms with west and east orientation respectively. The following table summarizes the results between two rooms that do not have any difference except of the facade orientation making clear that the influence of louvers and fabric rollers in east rooms will be similar.

60

2.7 Thermal comfort, Conclusions

Amount of hours that the indoor temperature exceeds 26oC (between 08:00-16:00) for two identical rooms with different facade orientation.

May

June

July

August

Sep

Total

West room with louvers

9,7

16,3

36

8,1

5,2

75,3

West room with rollers

16,0

23,2

45,8

17,8

7,6

110,4

West room with no sunshade

70,3

95,7

117,9

85,6

40,8

410,3

East room with louvers

32,6

46,2

66,1

28,6

9,2

182,7

East room with rollers

34,4

51,0

74

32,6

9,7

201,7

East room with no sunshade

68,6

110,4

113,8

76,7

20,5

390,0

Monthly average indoor temperatures (between 08:00-16:00) for two identical rooms with different facade orientation.

May

June

July

August

Sep

20,8

23,4 23,9

West room with no sunshade[ C]

24,3

26,0

23,8 24,2 25,7

22,4

21,4

23,8 24,2 26,4

East room with louvers [oC]

22,3

24,7

22,4

24,8

24,0

26,1

24,8 25,0 26,3

24,5 24,6 25,4

23,6

East room with rollers [oC]

o

West room with louvers [ C] o

West room with rollers[ C] o

o

East room with no sunshade [ C]

22,9 24,5

23,7 24,4

1.3 How does a corner room differ in thermal comfort from a classroom with one glass façade?

The thermal measurements showed that during the weekends, R205 is on average one degree warmer than the rest. So, the apparent conclusion would be that this was a result of the effect of the solar gains by the additional south façade. However, this assumption does not explain the whole truth and the reason was that the influence of the internal curtains in R205 hasn’t been considered.

From one point of view, the Capsol simulation proved that, the extra facade is a parameter that makes R205 the warmest room but only under the conditions that all the rooms haven't any sun shade. On the other hand, under the influence of sun shading the outcomes is quite different. An extra facade also means bigger heat losses, while, a bigger volume means smaller influence of the internal heat load. So, R205 is warmer than G104 and R203 but not from R209.

Summarizing, without using any sun shading system, the classroom with the biggest possibility of having discomfort problems is R205 (west orientation with two glass facades), while in a more realistic scenario using sunshade, the R209 (east orientation) will face higher thermal discomfort.

61

2.7 Thermal comfort, Conclusions

2.7.2 Effects of the old and new sunshading systems on thermal comfort (main research question) With the knowledge on the influences of the physical room characteristics in mind, we can discuss the main research question for thermal comfort: 1. What are the effects on the thermal comfort in the classrooms in different situations (different sunshade positions and different outdoor conditions), for the new and old sunshade?

Comparing the new sunshading system to the existing fabric rollers in terms of performance on thermal aspects, turned out to be difficult based on the measurement data.

In general, the measurement analysis showed that on the few weekdays with high direct radiation values, the room temperature is kept at levels that are similar to days with an overcast situation (for all rooms). Peaks and big temperature differences between the rooms during the week should mainly be assigned to internal gains and not to external gains. In addition, the temperatures results in R203 and R209 during this weekend, Saturday 29th and Sunday 30th of September, justify our first impression that both systems successfully reduce the temperature peaks from direct solar gains.

Capsol simulation More information on the effect of both systems on the room temperatures (without different room characteristics and conditions), was given by Capsol simulations.

The simulations confirm the first assumption made from the datalogger analysis that both louvers and roller can block most of the unwanted solar load. The g-value for the louvers was estimated to 0.1, and its U-values to 4.79 W/m2K, while for the fabric rollers to 0.2 and 5.48 W/m2K respectively.

However, the new louvers regulate the indoor temperature in a more efficient way.

In R203 and G104, the louvers are better but the benefit is not that drastic. In R205 though, the room with the two facades, it is clear that the new shading is much more effective than the old one, as the percentage of the hours that exceed 26oC using fabric roller is quite high (12.1%), while using louver drops to 6.0%.

In R209, there is a small, improvement by using rollers; however both systems fail to regulate the indoor temperature in a way that it does not exceed 26oC for less than 10% of the total occupant time. Thus, it seems that in the rooms with east orientation the new sun shading system do not make significant difference.

The reason behind that is the previous explained observation that the rooms with east orientation warm up faster that the ones with west orientation and under the influence of the internal heat load; they present higher average indoor temperature between 08:00 and 16:00. This phenomenon causes thermal discomfort during the warmer months of May and June. Thus, the heat removal becomes the main problem for the east rooms, and by blocking unwanted solar radiation the problem cannot be solved.

New sunshading system: effects of different louver rotations on thermal comfort The effect of different louver configurations was examined thoroughly during the weekend of September 29th and on Monday October 1st. These two cases are the most suitable because they reveal the influence of the different rotation of the louvers under different conditions. Firstly, during weekends when there is no internal heat loads, and secondly, during weekdays when the occupancy highly affects in the indoor temperature.

The analysis of the results showed that in order to prevent an overheating during the low west sunset, a very closed configuration of the louvers is needed (at least 55o). So, it was noticed that

62

2.7 Thermal comfort, Conclusions although the differences between the rotation of the louvers are small, an effect of on the rooms’ temperature is noticeable.

Relative humidity For all rooms the relative humidity sometimes exceeds the requirement of maximum 70%, and it is often higher than 60%. Especially when comparing it to other school studies the values seem high.

In the GGD study for High schools, there was an average of 45%, for 80% of the classrooms the RH was never above 60%, and only for lower than 1% of the classrooms the relative humidity goes above 60% half of the time. The relative humidity is in no case too low for the requirements.

Air quality The research question concerning air quality was: 2. What effect do the two different sunshade types have on the air flow and air quality in different situations?

There are a lot of complaints of the air quality in the survey, 60% of the children find the air musty at some moment. Also the velocity is often too high, about 60% of the students experience draught.

The CO2 levels are too high, only when 3 or more windows are open the values are acceptable, but this might be the cause of the draughts students complain about.

With two windows open and a closed door the refreshment rate is assumed to be 3. This situation does not give draughts, but the CO2 levels become too high in this situation when the room is occupied.

63

3.1 Visual comfort, Definitions

3. Visual Comfort Visual comfort is partly a subjective and psychological experience that can only be properly reviewed by involving user research. In the framework of this research we do not aim to cover the whole spectrum of the visual comfort, but we are more interested in the factors that affect the students' visual tasks.

The accuracy of the visual performance with which a visual task can be performed is related to the following factors (Baker & Steemers, 1999): 1. Sufficient illuminance of the task.

2. The apparent size of the details to be perceived on the task and the luminance-contrast between details and background.

3. The visual fatigue state.

Additionally, despite the common misconception that surface illuminance is the only relevant parameter for visual comfort, a more comprehensive attitude to visual perception is needed. This should include notions of: spatial distribution of daylight illuminance, luminance ratios, shape from shadows, colour rendering, glare, visual noise etc (Baker, Fanchiotti, & Steemers, 1993). Thus, it is clear that despite the complexity of the visual comfort there are two notions that prevail; the illuminance levels and the luminance contrast.

As mentioned in chapter 1.3, in the framework of our study in Gertrudis College, the research questions related to the visual comfort are: 1. What are the illuminance levels in the classrooms in different sunshade positions, for the new and old sunshade?

2. What is the general luminance contrast in the classrooms, in different sunshade positions, for the new and old sunshade?

3. What is the influence of the positions of the sunscreens (old and new) on the visibility of whiteboard/ blackboard, TV-screen and smart board?

Even though luminance and illuminance are dependent on each other, we could say that the illuminance levels will give us information to answer question 1 which is related to visual performance, while the luminance contrast is related to questions 2 and 3.

3.1 Definitions In this chapter we will discuss the terms and units that play an important role for the calculations of the daylight performance. These key terms for lighting studies are explained below.

3.1.1 Illuminance Luminous flux (Ď•) [lumen] The amount of light energy flowing through a particular volume of space.

Illuminance (E) [lux] It is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception. In other words this is the factor that describes the light sufficiency.

64

3.1 Visual comfort, Definitions

E= E = illuminance [lux], dφ = de luminous flux [lm] en dS = surface of the luminous flux [m2 ]

3.1.2 Daylight factor Daylight factor (DF) [%] This is the proportion of the unobstructed external daylight illuminance that reaches a point inside the room. In other words, it is the ratio between the indoor illuminance and the illuminance outside, measured during an overcast sky.

DF =

( . )

DF = Daylight factor [%] Ep= measured illuminance in specific point [lux] Ehor (f.f) = illuminance outside in horizontal plane in free field.

It is almost impossible to measure the outside illuminance in the horizontal plane in free field, because of the present obstacles. So, it is usual to measure the outside lux in the vertical plane right behind the window and convert this value to the horizontal plane in free field. In this case we have to take into account the pollution of the windows and obstacles if present, and apply a reduction factor.

Evert(glass) = cr ∙ Evert Evert(glas) = illuminance behind the window in vertical plane [lux] cr = reduction factor Evert= illuminance outside in vertical plane

The last step is the conversion of the vertical outside illuminance to the horizontal outside illuminance in free field.

Evert = 0,396 ∙ Ehor(f.f.)

Evert= illuminance outside in vertical plane Ehor (f.f) = illuminance outside in horizontal plane in free field.

3.1.3 Luminance Luminance (L) [cd/m2] This is a measure of the luminous intensity of light emitted or reflected in a given direction, divided by the area of the surface. It is often confused with the term brightness, but brightness refers to the human appreciation of the luminous intensity. (Helms & Belcher, 1980)

L( ) =

( ) ∙

65

3.1 Visual comfort, Definitions L( ) = Total luminance [cd/m2] I( ) = luminous intensity [cad] A = luminous intensity surface Cos = incident angle

The luminance that is reflected from the surface, is diffuse reflected, and is therefore calculated differently than the total luminance.

L=

∙

L = Reflected luminance [cd/m2] r = Reflection coefficient surface E = illuminance [lux]

3.1.4 Discomfort glare and Luminance contrast High or non-uniform luminance distribution within the visual field may cause discomfort sensation even if little or no decrease in visual performance is observed. This phenomenon is known as 'discomfort glare'. It originates from an instability in the control mechanism of the visual system (Baker & Steemers, 1999).

Glare is complex and can be categorized into two major types, direct and indirect. Direct glare is due to any excessively bright source of light (luminaries or windows) in the field view that shines directly into the eyes, resulting in discomfort and a loss in visibility. Indirect glare is due to any excessively bright source of light coming to the eyes indirectly (by reflection) causing a loss in visibility. These are two forms of indirect glare, which are called reflected glare and veiling reflections (specular reflections that appear on the object viewed and that partially or wholly obscure the details by reducing contrast). (Helms & Belcher, 1980) Many studies conducted more than 50 years ago have shown that the magnitude of the discomfort glare sensation is directly related to the luminance of the glare source and its apparent size as seen by the observer. In addition, discomfort is reduced if the source is seen in surroundings of high luminance. The glare sensation is also reduced the further the glare source is off the line of sight (Baker & Steemers, 1999).

In our study we are interested in two discomfort glare phenomena. The one is the possibility of discomfort glare from the window (daylight). The other is the reflected glare on the blackboard/whiteboard or TV screen.

Figure 60: The parameters taken into account to compute discomfort glare indices.

Figure 59:The resulting effect of visual adaptation.

66

3.1 Visual comfort, Definitions

3.1.5 Performance indicators for discomfort glare Unified glare rating (UGR) The last 30 years the research for the discomforted glare focused more on the artificial lighting.

Thus, in that case the discomfort glare is measured mainly by an empirical formulae using a socalled 'glare index' scale. Various slightly different versions have been proposed. The latest one recently defined by the CIE is called the 'unified glare rating' (UGR) (Baker & Steemers, 1999). Since more than one glare source may be present, the formula involves a summation: UGR=8log

.

∑

Where: Li = luminance of the glare source i wi = the solid angle subtended by the source i Pi = the position factor Lb = the mean luminance of the remaining parts of the field of view.

UGR values below 10 mean imperceptible glare. Glare becomes really uncomfortable for UGR values above 22. Values above 28 denote intolerable glare sensations.

Daylight Glare Index (DGI) However, in our case we are more interested in the discomforted glare caused by daylight. To account the differences between the discomfort glare caused by artificial light and daylight researcher have defined a specific 'daylight glare index' (DGI) (Baker & Steemers, 1999). Its mathematical definition (known as the Cornell formula) is slightly more complicated than that for the UGR but remains of very similar nature. In a way DGI is a transformation of the UGR in order to be applicable for predicting discomfort glare from large sources such as windows.

DGI= 10

0.478 ∑

.

.

. .

(Chauvel, Collins, Dogniaux, & Longmore, 1982)

Ls = the average luminance of each glare source in the field of view [cd/m2] Lb = the average luminance of the background excluding the glare source Lw= the average luminance of the window ω = the solid angle of the source seen from the point of observation Ω = the solid angle subtended by the source n = number of glare sources.

With DGI up to 16, glare remains imperceptible. DGI values over 24 denote an uncomfortable glare sensation, becoming intolerable above 28.

Luminance ratios The DGI method is relatively new and it is still in an experimental stage. For that reason this method is not mentioned in the International standard regulation, instead European Norms and International standard regulation for visual comfort and discomfort glare still suggest the use of rule of thumbs based on Luminance Ratios (LR).

Additionally, the use of DGI also requires the use of specific simulation software, Radiance would be the most suitable for that reason. Thus, due to simplification and reliability, it was decided to use Luminance Ratios (LR) for defining the extent of direct discomfort glare from the incoming daylight from the windows and the indirect glare (mirroring) on whiteboards/ blackboards or TV screens (LR requirements see chapter 3.2.2).

67

3.2 Visual comfort, requirements

3.2 Requirements 3.2.1 Illuminance Levels requirements Every task has a specific light requirement. Therefore, it is important to take into account the tasks that need to be executed in the space to judge the measured values properly. In our case it concerns several classrooms in a high school, so the tasks in the spaces are very specific.

The recommended design illuminance for different types of classrooms range from 300 to 500 lux.

Adoption of such values helps to restrict glare to reasonable levels (Winterbottom & Wilkins, 2009).

Dutch regulations like the NEN12464-1 do mention a specific minimal requirement for lux levels in classrooms. It does not go into detail about required lux levels for smartboards or TV screens.

The NEN 3087 only mentions a minimum level of 200 lux to prevent visual discomfort. This regulation doesn’t mention any comfort levels specifically for education spaces. There are some researches that focus on the daylight quality within school buildings. An example of such a research is an initiative of the Dutch government 'design guide 100% clean light in schools.’ This research sets the following lux levels for the different kind of tasks in a classroom: Reading Computer work White boards Smartboards (plane for beamer projection)

300 lux 300 lux 300 lux (vertical) 100 lux (no direct sunlight)

Daylight Factor Figure 61 shows during which percentage of the time, the minimum amount of illumination is present outside in the free field.

80% is the target requirement in order to limit in reasonable levels the use of artificial light, this corresponds with an outside lux level of 8250.

If the previous value (outside level of 8250 lux) and the minimum lux requirement on the horizontal plane (300 lux) are known, then, the minimum daylight factor can be calculated: DF =

= 3,6 % (horizontal working plane)

DF =

= 1,2 % (vertical plane, smartboards)

Figure 61: Illuminance on horizontal free field

68

3.2 Visual comfort, requirements

3.2.2 Luminance Ratios requirements In this part attention will be paid to two discomfort glare phenomena. The one is the possibility of discomfort glare from the window (daylight) while the students have their focal attention on the centre of the room(see visual comfort research question 2). The other is the reflected glare on the blackboard/whiteboard or TV screen (see visual comfort research question 3).

In addition, a luminance ratio is always related to a specific visual field. The closer the brightest source is to our focal main target, the bigger the problem it creates to our visual performance.

Thus, all the luminance ratios that are going to be used as requirements are related to the visual field.

The visual field The visual field is bounded by a cone of approximately 140o apex (equal to visual field of 70o). It comprises three distinct parts that have quite different characteristics. In the centre a restricted zone bounded by a cone of 1o apex is called the "area of central vision". A second circular zone delimited by a cone of 60o apex (equal to visual field of 30o) encircles the central area. This zone is called the 'ergorama' since it usually embraces a portion of the space containing various objects that are necessary to perform a working task (e.g. a computer workstation with its screen and keyboard close to paper documents) (Baker & Steemers, 1999). Finally the 'panorama' fills the outer part of the visual field. Its extent is limited by the nose, forehead and cheeks. In the panorama, objects are hardly noticeable unless they move. This division of the field of view is used mainly for luminance ratio criteria.

Figure 62 shows the approximate extent of the visual field of the two eyes in humans and the overlap between them.

Figure 63: The three Luminance ratios used in our study.

Figure 62: The human eyes visual field.

(LR)- panorama According to IESNA (IESNA Lightting Handbook, 9th Edition, 2000), (IES Lighting Handbook, 1981), a maximum luminance ratio of 40:1 should be respected between points anywhere in the entire field of view. In Sweden, NUTEK (NUTEK, 1994-11) has stricter recommendations as the LR between any points within the field of view should not exceed 20:1. On the other hand the Dutch regulations (NEN3087 Visual ergonomics) indicate that the luminance ratio between the mean luminance of a task and the brightest source visible in the entire human perception visual field should not exceed a ratio 30:1.

69

3.2 Visual comfort, requirements Considering all the previous regulations, it was decided that for a visual field of 60o (panorama), the restriction of 30:1 will be used. (

LR (60o) =

)

(

)

<

Lmax (6o) is the maximum visible bright source. In case only of daylight conditions, the brightest source usually comes from the window, however with the influence of artificial lighting, the luminaries (depending on the viewing angle and the position of the sunscreens) might replace the window as the brightest light source.

Lmean(background) is the average luminance of the interior without including the bright source from the window. This is suggested in the Dutch NEN3087.

(LR)- ergorama Between the task and remote (nonadjacent) surfaces the previously mentioned norms suggest a Luminance ratio of 10:1.

LR (30o)=

(

)

(

)

<

Lmax(30) is the maximum bright source restricted in a visual field of 30o.

Finally to limit discomfort glare, between the task and the adjacent surroundings, IESNA (IESNA Lightting Handbook, 9th Edition, 2000) and the British equivalent CIBSE (Code for interior lighting, 1994) recommend that the Luminance ratios (LR) should not exceed 3:1. This is the LR that will be used to define the mirroring glare in the whiteboards/blackboards or TV screens.

LR (task)=

(

)

(

)

<

Ltask will be the surface of whiteboard/ blackboard. However, this rule of thumb does not give reliable results for object that emit light like TV screens. The way that this problem was solved is explained in chapter 3.5.1 Measurement method of the luminance ratios.

3.3 Survey results Most of the visual problems are profound by a simple, on site observation. However, specific questions focusing on visual discomfort were part of the survey that the students and teachers had to participate. Except of personal observations, it also was necessary the users perspective on the visual comfort.

For analyzing the outcome of the survey and to get a better insight in the nature of the problems, the classroom surface was devised in four zones (see Figure 64).

Figure 64: Zones of room

70

3.3 Visual comfort, Survey results The survey contained several questions about the visual comfort in the space. The graphs below give an overview of the outcome of these questions.

What is your overall impression of this room? (5 light-1 dark) all classrooms 3,80

3,64

Zone A

Zone B

3,60

3,59

Zone C

Zone D

Figure 65: Results of survey, overall impression of room in different zones

Can you properly read the smartboard/TV screen?- YES 86% 63% 33%

25%

Zone A

Zone B

Zone C

Zone D

Figure 66: Results of survey, readability of smartboard in different zones Is your book easy to read?

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

Book Visible

yes

barely

no

Figure 67: Results of survey, readability of book

71

3.3 Visual comfort, Survey results

Have you ever suffered from health problems (headaches, loss of concentration), related to the light in the room?

60% 50% 40% 30% Health Problems 20% 10% 0% Never

Sometimes

Often

Figure 68: Results of survey, health problems due to light

Health problems per zone 35 30 25 20

Never

15

Sometimes

10

Often

5 0 Zone A

Zone B

Zone C

Zone D

Figure 69: Results of survey, health problems per zone

Based on the survey outcomes and our own experiences, we can identify the following problems: -

Students experience mirroring watching the TV screens in zone A and D.

-

There are difficulties with the visibility of the beamers/smart boards.

-

Health problems do occur caused by too bright light or difficulties watching the screens in the classrooms.

-

The majority of the health problems occur in zone A and zone B.

3.4 Illuminance measurements In order to investigate the lighting quality and the visual comfort in the classrooms, especially related to the placement of the new sun shading, lighting measurements were executed in 2 different classrooms (R203 and W107) of the Gertrudis College combined with surveys for the users of the rooms. One classroom is fitted with the new sun shading (R203), and the other one still has the old sun shading (W107). Both classrooms have the same orientation. For these measurements G104 will not be investigated, because it has the same geometric properties and materialization as R203, but does have more obstacles outside in front of the window.

72

3.4 Visual comfort, Illuminance measurements

3.4.1 Measurement method Illuminance (E) [lux] This aspect is measured on two different ways. (a) The first illuminance data were obtained from the installed dataloggers. These loggers have been placed vertically, on a wall where the blackboard is installed. This data does not give an impression of the overall illuminance in the classroom in the horizontal plane, but will be useful for analyzing the changing conditions during the weeks. (b)The second method for measuring the illuminance gives a better insight of the overall illuminance in the classroom in the horizontal plane at working height of the student. With the use of a lux meter, the illuminance was measured on the student desks of on 16 different points (see Figure 70 and Figure 71) distributed in a regular grid by hand. At each point, illuminance levels were assessed under eight lighting conditions: (1) Lights on, blinds open (2) Lights off, blinds open (3) Lights on, blinds closed (4) Lights off, blinds closed (5) Lights on, blinds horizontal (6) Lights off, blinds horizontal (7) Lights on, blinds 45 degrees (8) Lights off, blinds 45 degrees In W107 (fabric rollers) only the four lighting condition (with and without sunshade) are possible.

In R203 , with the new sunshade, all situations (open, closed, horizontal and 45°) are possible.

Besides the points on the student desks, also measurements were made on three spots of the TV screen or smartboard in the vertical plane, as well as on the teacherâ&#x20AC;&#x2122;s desk in the horizontal plane.

During these measurements, the outside lux levels have been measured simultaneously with every inside measured point.

Figure 70: Measurement points room R203

Figure 71: Measurement points room W107

73

3.4 Visual comfort, Illuminance measurements

3.4.2. Results illuminance measurements The following graphs show the Illuminance levels in the horizontal plane of the classrooms in the different points with the different positions of the sun shading measured with an overcast sky outside. The data for the illuminance and daylight factor for the totally closed position of the sunscreen have been left out, because the values are close to 0. The complete overview of measured values can be found in Appendix F, Table F- 1 to Table F- 12.

R203 Artificial light OFF Illuminance (lux)

Daylight factor (%)

No sunshade

Lux

No sunshade

1400 1200 1000 800 600 400 200 0

10,0% 8,0% 6,0% 4,0% 2,0% 0,0%

Figure 72: Illuminance for R203, sunshade up, artificial light off

Figure 73: Daylight factor for R203, sunshade up, artificial light off

Louvers Horizontal

Louvers Horizontal

Lux

10,0%

1400 1200

8,0%

1000 800

6,0%

600

4,0%

400 200

2,0%

0

0,0% Zone A Zone B Zone C Zone D

Zone A Zone B Zone C Zone D

Figure 74: Illuminance for R203, sunshade horizontal, artificial light off

Figure 75: R203, sunshade horizontal, daylight factor, artificial light off

74

3.4 Visual comfort, Illuminance measurements

R203 Artificial light OFF Illuminance (lux) Louvers tilted Lux

Daylight factor (%) Louvers tilted

1400

10,0%

1200

8,0%

1000 800

6,0%

600

4,0%

400 200

2,0%

0

0,0% Zone A Zone B Zone C Zone D

Zone A Zone B Zone C Zone D

Figure 76: R203, Sunshade tilted 50째, illuminance, artificial light off

Figure 77: R203, sunshade tilted 50째, daylight factor, artificial light off

R203 Artificial light ON Illuminance (lux) No sunshade Lux

Illuminance (lux) Louvers horizontal Lux

1400

1400

1200

1200

1000

1000

800

800

600

600

400

400

200

200

0

0 Zone A Zone B Zone C Zone D

Zone A Zone B Zone C Zone D

Figure 78:Illuminance R203, sunshade up, artificial light

Figure 79:Illumin. R203, shade horizontal, artificial light

Louvers tilted

Sunshade closed

Lux

Lux

1400 1200 1000 800 600 400 200 0

1400 1200 1000 800 600 400 200 0 Zone A Zone B Zone C Zone D

Zone A Zone B Zone C Zone D

Figure 80L Illuminance R203, shade tilted, artificial light

Figure 81:Illuminance R203, shade closed, artificial light

75

3.4 Visual comfort, Illuminance measurements W107 Artificial light OFF Illuminance (lux)

Daylight factor (%) No sunshade

No sunshade 16,0% 14,0% 12,0% 10,0% 8,0% 6,0% 4,0% 2,0% 0,0%

1400 1200 1000 800 600 400 200 0

Zone A Zone B Zone Zone C D

Zone A Zone B Zone Zone C D

Figure 83: DF W107, shade up, artificial light off

Figure 82: Illum.W107, shade up, artificial light off

Sunshade closed

Sunshade closed 1400 1200 1000 800 600 400 200 0

16,0% 14,0% 12,0% 10,0% 8,0% 6,0% 4,0% 2,0% 0,0% Zone A Zone B Zone Zone C D

Zone A Zone B Zone Zone C D

Figure 84: Illum. W107, shade down, artificial light off

Figure 85: DF W107, shade down, artificial light off

W107 Artificial light ON Illuminance (lux)

Illuminance (lux)

No sunshade

Sunshade down

1400

1400

1200

1200

1000

1000

800

800

600

600

400

400

200 0

200 0 Zone A Zone B Zone Zone C D

Zone A Zone B Zone Zone C D

Figure 86: Illum. W107, shade up, artificial light on

Figure 87: Illum. W107, shade down, artificial light on

76

3.4 Visual comfort, Illuminance measurements Table 14: Results of measurements on the board for R203

R203 Board1

Figure 88: Measurement points on the board, vertical plane

As we can see in the table for the illuminance levels on the board in R203, only the situations with the sun shading at 45 degrees and totally closed without artificial light meet the requirement we set for the illuminance levels on the smartboards <100 lux. With the sun shading in 45 degrees with artificial light on, one value at the right side of the board is higher than 100 lux. We can see that this is the second best option in R203 in terms of visibility of the smartboards.

In W107 where they still have the old sun shading, the level of <100 lux is only realized with the sun shading down and not artificial light.

Board2

Board3

up hor.

45o down

181 177 60 3,5

173 151 51 2

178 no 138 artificial 46 light 1

up hor.

45 down

205 231 274 88

215 219 123 85

245 244 Artificial light 116 138

Table 15: Results of measurements on the board for W107

Board1 165

W107 Board2 170

down

82

77

no artificial 71 light

up down

339 391

310 231

178 Artificial light 202

up

Board3 161

Problems Visual Performance - Uneven daylight distribution in the classrooms, too low daylight factors in zone C and D - Uneven artificial light distribution, problems in zone A and zone D - Too low daylight factors in the classrooms with new sun shading horizontal and on 45 degrees without artificial light.

Conclusions To point out a situation that meets both requirements in the horizontal and vertical plane is difficult. Especially for good visibility of the beamers in the current situation, illuminance levels below 100 lux are desired. Meeting this requirement implicates too low illuminance values in the horizontal plane for executing the student tasks (>300 lux). A critical note needs to be placed at the maximal level of 100 lux in the vertical plane for the beamers. It is a very low value, which is difficult to meet in these giving classrooms. Another solution is to place stronger beamers or TV screens. In that case, the requirement of a maximum of 100 lux can be adjusted to a higher value, which is easier to reach in the given circumstances in the classrooms.

The best situation in terms of visual performance based on our overcast field measurements is the sun shading at 45 degrees with artificial light on. This situation gives the best balance between low illuminance levels on the boards and sufficient illuminance levels in the horizontal working plane.

The remaining problems are the zones on the sides of the classroom with insufficient artificial light.

From an economical and sustainable perspective, the situation with the sun shading at 45 degrees and the artificial light on, does not give that many advantages, compared to the situations without artificial light.

77

3.4 Visual comfort, Illuminance measurements R203_No artificial light Board 1 Board 2 Board 3 60 lux 51 lux 46 lux

45째

Down

R203 sunshade tilted

W107 sunshade down

600

600

500

500

400

400

300

300

200

200

100

100

0

0 Zone A Zone B Zone Zone C D

Zone A Zone B Zone C Zone D

Figure 89: Illuminance for R203, tilted sunshade, artificial light off

Closed

W107_No artificial light Board 1 Board 2 Board 3 82 lux 77 lux 71 lux

Figure 90: Illuminance for W107, sunshade down, artificial light off

R203_Artificial light on Board 1 Board 2 Board 3 88 lux 85 lux 138 lux sunshading CLOSED

600 500 400 300 200 100 0 Zone A Zone B Zone C Zone D

Figure 91: Illuminance for R203, closed sunshade, artificial light on

78

3.4 Visual comfort, Illuminance measurements

3.4.3 Illuminance levels Datalogger analysis In the next table the average, minimum and maximum illuminance values per room are measured by the dataloggers. Table 16 shows that G104 and R209 have higher average illuminance values.

But the results are highly influenced by the position of the dataloggers within the rooms. For example rooms R203 and G104 have a similar geometry, even though one is on the first floor (G104) and the other on the second floor (R203). But due to the placement of the dataloggers room G104 has much higher values in week 39. In the second week both had more similar values.

G104 has a relatively higher peak, probably because it is on the west side of the building. R209 shows a relatively high average, which might be because it has a more constant lighting during the whole day.

Table 16: Average illuminance values

Week 39 Emin (Lux) Emax (Lux) Eavg (Lux) Week 40 Emin (Lux) Emax (Lux) Eavg (Lux)

R209

R203

G104

R205

68.3 1342.9 537.9

11.8 809.4 140.4

34.2 1709.5 458.7

36.8 477.0 144.2

48.6 814.7 427.4

17.1 1411.2 241.7

34.2 1420.4 365.4

19.7 981.5 124.6

Use of sunscreen

From the controller station of the new sunscreens, usage data was retrieved for week 40. With this data it is possible to compare the use of the new sunscreens to the illuminance levels measured with the dataloggers.

In Figure 92 the new sunscreens in room G104 can be seen. The illuminance levels are deviating due to the use of the sunscreen. Sometimes when the illuminance levels are very high, the sunscreen is not used.

In room R205 with two faรงades with windows (Figure 93), the louvers were used just as much as in G104, but the louvers were overall more closed/vertical (see 2.4.4 Room temperature and use of the sunscreens).This could be why the illuminance values are lower for R205, but this could also be due to the placement of the datalogger, which was further into the room.

The South louvers are less used, because there is also shading on this side from the building next to it. Therefore, there is usually no direct glare from the south side.

79

3.4 Visual comfort, Illuminance measurements

5

3000 2750

4

2250 2000 3

1750 1500 1250

2

1000 750

Position sunscreen

Illuminance (Lux)

2500

1

500 250

0

0

Position sunscreen (0=up, 1=half closed horizontal, 2=lamels horizontal, 3=lamels 30, 4=lamels 55, 5=lamels vertical) Illuminance

Figure 92: Illuminance levels versus the louver sunscreen positions for G104

6

3000 2750

5

2500

4

2000

Illuminance (Lux)

1750 3

1500 1250

2

1000

Position sunscreens

2250

750 1

500 250

0

0

Position West sunscreen (0=up, 1=half closed horizontal, 2=lamels horizontal, 3=lamels 30, 4=lamels 55, 5=lamels vertical) Position South sunscreen Iilluminance

Figure 93: Illuminance levels versus the louver sunscreen positions for R205

Use of artificial light With the help of the longitudinal questionnaires (logbook filled in by the teachers) it was possible to see the use of the artificial light in some rooms. When the light was off it is shown in Figure 94 as 1, when it is on it is shown as 2. When there is no data from the longitudinal questionnaire it is 0.

Room R209 uses less artificial light, when comparing it to the results of the tutor logbooks for R205 and G104. In these rooms it was never reported that the artificial light was off. This could be 80

3.4 Visual comfort, Illuminance measurements explained by the fact that R209 gets higher illuminance levels in the morning. West rooms use the light 4 hours during morning. This could also be explained by more use of the sunscreens in the west rooms.

The artificial light is usually on in room G104 and R205, independent of the sunshade positions and the time of the day (see Appendix E, Figure E- 7 to Figure E- 10). Also in R209 it is on most of the day.

Illuminance levels and artificial light (R209) 2250

2

2000

1500 1250 1 1000 750

Artificial light

Illuminance (Lux)

1750

500 250 0 Mon. 09/24 24:00

8:00

16:00

Tu. 09/25 24:00

8:00

16:00

Wed. 8:00 16:00 Thu. 8:00 16:00 Fri. 26/12 09/27 09/28 24:00 24:00 24:00 Artificial light on (2=yes 1=no) Illuminance

8:00

16:00

0 Sat. 09/29 24:00

Figure 94: Illuminance levels versus artificial light use in room R209

3.5 Luminance measurements 3.5.1 Measurement method Critical points Firstly, it was necessary to define the critical viewpoints which present the highest discomfort glare probability in order to take the luminance pictures. It was decided that in every classroom there were 7 critical viewpoints, two from the teacher's view (T1,Tav), and five from students' view (S1,S2,S3,S4,Sav) (see Figure 95). All pictures in every point are taken under the same 8 different positions of the shading system, similarly to the illuminance measurements (see chapter 3.4.1).

The choice of the critical points was based both on personal observations and the survey analysis (see chapter 3.3). One simple example that justify this choice for the critical points derives from the comparison of Figure 97 and Figure 99, where it is clear that the differences in LR(30o) from position S1 and S3 are significant as the bright source from the window is not Figure 95: critical points for luminance always included in the visual field.

81

3.5 Visual comfort, Luminance measurements pictures.

Figure 96: Visual field from critical point S1 (floor plan).

Figure 98: Visual field from critical point S3 (floor plan ).

Figure 97: Visual field from critical point S1 (luminance picture).

Figure 99: Visual field from critical point S3 (luminance picture).

In this chapter, except of the evaluation of the different sun shading systems in preventing the discomfort glare from the windows, we also want to test their effect on the visibility of different task surfaces (see Figure 100-Figure 103) for blocking the reflected glare (mirroring). For that reason the luminance pictures were taken in classrooms R203 (new sun shade, whiteboard and smart board), G104 (new sun shade, TV-screen) and W107 (old sun shade, blackboard).

Figure 100: Whiteboard (R203)

Figure 101: Blackboard (W107)

Figure 102: Smartboard(beamer projections) (R203)

Figure 103: TV screen (G104)

82

3. 5 Visual comfort, Luminance measurements Limitations in the use of luminance ratios (LR) TV screens During the calculation of LR for indirect glare (mirroring) on task surfaces, it was observed that the luminance ratio recommendations, as explained in chapter3.2.23.2.2 Luminance Ratios requirements, were inaccurate for TV screens because they are self emitting objects. However, the mirroring problem was similar both for TV screens as well as for whiteboards. Thus, the results for the efficiency of the louvers for preventing the mirroring in whiteboards, could be also used for the TV screens. Figure 104 and Figure 105 reveal the similarity of the mirroring phenomenon in whiteboards and TV screens due to similar surfaces glossiness. Thus, the pictures taken from G104 won't be analysed in detail but they will be used to verify the conclusions macroscopically.

L[cd/m2]

Figure 104: R203, whiteboard view from S1 (position of the louvers up).

Figure 105: G104, TV screen view from S1 (position of the louvers up).

Smart boards Another difficulty was the calculation of LR for smart boards (beamer projection surfaces). At the end, this case was excluded from the luminance analysis as it was observed that there were no significant problems related to mirroring. In addition, the light conditions, for viewing a projection from a beamer, require very low surrounding illuminance levels. Thus, the problem with the visibility of the smart boards was in a way covered from the illuminance analysis (see chapter 3.4.2).

In general, conventional slide projector screens have a matt surface that reflects incident light in every direction so the image can be seen from any viewing angle. More glossy surfaces, like the whiteboards or TV screens, do not scatter light so well, they reflect some of the light at an angle equivalent to the angle of incidence in the same way as a mirror (specular reflection) (Winterbottom & Wilkins, 2009) Finally, the analytical comparison for the visual comfort due to glare between the new and the old sun shade system was made in R203, which is a room with a whiteboard, and room W107 which has a blackboard. So, for the discomfort glare in a visual field of 60o and 30o we can make a direct comparison, but for blocking the mirroring in a board we have to be more critical as a white board and a blackboard have similar mirroring problems but different glossiness and colour surface.

83

3.5 Visual comfort, Luminance measurements

3.5.2 Calculation method (LR) Purpose of this chapter explain the calculation method of the luminance ratios, also examples from R230 and W107 will be presented.

The calculations for the luminance ratio were made with the use of 'LMK2000 mobile advanced' from Techno Team Bildverarbeitung GmbH. This software converts RAW images from a calibrated DSLR camera into luminance pictures, giving precise luminance levels for selected areas in the picture.

Examples of luminance sampling (R203)

Figure 106: Luminance sampling in R203. Louvers up, only daylight.

Figure 107: Luminance sampling in R203. Louvers in horizontal position, only daylight.

Figure 108: Luminance sampling in R203. Louvers tilted in 45o, only daylight.

Figure 109: Luminance sampling in R203. Louvers closed, artificial lighting.

84

3. 5 Visual comfort, Luminance measurements For the needs of every LR, it was necessary a luminance sampling specifically designed in order to calculate values like L(max 60o), L(mean background) etc. In Figure 106 - Figure 108 we see the sampling method under daylight conditions for R203, the sampling is made through circular or rectangular calculation surfaces. The purpose of these measurements is explained analytically in the following index, (the numbers are the identical to the calculation matrices, as they are presented in the figures): 1. Sampling in visual field 60o. This is necessary for tracking the position of the brightest light source from the window. However, the maximum value of this sampling is not used as Lmax(60o) neither the mean value as Lmean(background). The bright source from the sky is not homogeneous and it changes constantly. So, in order to avoid unrealistic values that might affect the reliability of the luminance ratios, it was decided to use as L max(60o) the mean value from a closed area around the maximum value. This is the value from raw 5.

2. Sampling in visual field of 60o excluding the window in order to calculate the Lmean(background).

3. Sampling in visual field of 30o. This calculation surface gives the Lmax(30o).

4. Sampling in the whiteboard. This gives the Lmax(task) and Lmin(task).

5. Sampling in a small area of the façade close to the brightest outside source. This gives the L(mean)brightest source that is actually the value used as L max(60o).

In Figure 109, which resembles a situation with artificial light, a 6th calculation line has been added.

6. This calculation line determines the Lmean (luminaire).

Table 17: Luminance values from Figure 106

Lmean

Calculation surface 1 2 3 4 5

[cd/m²] 151.1 68.14 76.39 346.1 4067

(60o) (60o) excluding window (30o) (task) whiteboard (60o) brightest source

Lmin [cd/m²] 0.8757 0.8757 1.485 94.88 2041

Table 18: Luminance values from Figure 107

Lmax [cd/m²] 4890 1893 821.6 821.6 4630

Calculation surface (60o)

1 2 3 4 5

(60o) excluding window (30o) (task) whiteboard (60o) brightest source

Calculation surface 1 2 3 4 5

[cd/m²] 34.66 14.51 14.48 67.85 690.2

(60o) (60o) excluding window (30o) (task) whiteboard (60o) brightest source

Lmin [cd/m²] 0.2041 0.2041 0.3462 29.62 175.4

Lmin [cd/m²] 0.4096 0.4096 0.8067 105.5 606.2

[cd/m²] 89.35 44.19 63.09 323.6 1590

Lmax [cd/m²] 2716 971.6 752.5 752.5 2705

Table 20: Luminance values from Figure 109

Table 19: Luminance values from Figure 108

Lmean

Lmean

Lmax [cd/m²] 1207 793.7 146.4 146.4 1107

Calculation surface (60o) (60o) excluding window (30o) (task) whiteboard (60o) brightest source (60o) artificial lighting

1 2 3 4 5 6

Lmean

Lmin [cd/m²] 0 0 0.4824 23.01 40.57 1199

[cd/m²] 35.7 34.32 18.68 35.35 177.5 1299

Lmax [cd/m²] 1437 1437 801.4 50.64 775.4 1395

Calculation examples in R203 In the following example shows how the LR has been calculated in practice, (the example is from R203 under daylight conditions, with louvers up): (

LR (60o) = LR (30o)= LR (task)=

)

( (

) )

(

)

(

)

(

)

<

<

<

(

→ LR (60o) =

→ LR (30o) = → LR (task) =

( ( (

°) )

(

)

(

)

85

=

°)

=

°) .

/ ²

.

/ ²

=

.

= . .

/ ² .

/ ²

< / ² / ²

=

.

>

=

.

>

3.5 Visual comfort, Luminance measurements

In case of artificial lighting, the brightest source derives from the comparison between the window and the luminaries. In the example presented in Figure 109 (R203 with artificial light and the louvers closed) as it is expected the maximum luminance value is due the artificial light.

LR (60o) =

(

)

(

)

<

(

→ LR (60o) =

°) (

=

°)

/ ² .

/ ²

=

.

>

Thus, we can notice that the artificial planning in the room is not the best possible, as the LR (60o)=36:1 which is slightly above the limit of 30:1.

Examples of luminance sampling (W107) In general the same process is followed for W107, the room with the old fabric rollers. The following example is a LR comparison from Sav between two different conditions: (a)fabric rollers up under daylight conditions and (b)rollers down and artificial lighting.

Figure 111: Luminance sampling in W107. Fabric rollers down, daylight and artificial lighting.

Figure 110: Luminance sampling in W107. Fabric rollers up, only daylight.

Table 21: Luminance values from Figure 106

Lmean

Visual field 1 2 3 4 5

[cd/m²] 787.4 727.4 725.7 203.3

(60o) (60o) excluding window (30o) (task) whiteboard (60o) brightest source

9231

Lmin [cd/m²]

Table 22:

Lmax [cd/m²]

Lmean

Visual field

6.988 6.988 11.07 132.2

13040 8128 13010 459

675.3

12770

1 2 3 4 5 6

[cd/m²] 128.4 97.92 74.57 33.59 848.8 2869

(60o) (60o) excluding window (30o) (task) whiteboard (60o) brightest source (60o) artificial lighting

Lmin [cd/m²] 1.775 1.775 1.775 26.78 745.4 1295

Lmax [cd/m²] 4356 4010 921.9 74.75 928.3 4010

Calculation examples in W107 In this example, compared to for the previous, an interesting conclusion can be made, the artificial lighting in LR (60o) does not create discomfort glare.

LR (60o) =

( (

) )

=

(

°) (

°)

=

/ ² .

/ ²

=

<

The LR for all the critical viewpoints in all the different conditions can be found in Appendix F: Tables visual comfort.

86

3. 5 Visual comfort, Luminance measurements

3.5.3 Luminance ratio results Luminance Ratios in R203 - Daylight LR (30˚) < 10:1 R203 - daylight

LR (60˚) < 30:1 R203 -daylight 70 60 contrast ratio

contrast ratio

50 40 30 20 10 0 up

hor

tilted

up

closed

Figure 112

hor

tilted

closed

tilted

closed

Figure 113 LR, whiteboard < 5:1 R203-daylight

30

contrast ratio

90 80 70 60 50 40 30 20 10 0

25

S1

20

S2 S3

15

S4

10

Sav

5

T1

0 up

hor

tilted

closed

Figure 114

Luminance Ratios in R203 -Daylight and artificial lighting LR (60˚) < 30:1 R203

LR (30˚) < 10:1 R203

70

25 20

50

contrast ratio

contrast ratio

60 40 30 20

15 10 5

10 0

0 up

hor

tilted

closed

up

Figure 115

Figure 116

87

hor

3.5 Visual comfort, Luminance measurements

LR (whiteboard) < 5:1 R203

contrast ratio

25 20

S1

15

S2

10

S3

5

Sav

0 up

hor

tilted

closed

Figure 117

Luminance Ratios in W107 -Daylight and artificial light LR (60Ë&#x161;) < 30:1 W107

LR (30Ë&#x161;) < 10:1 W107

70 contrast ratio

contrast ratio

60 50 40 30 20 10 0

90 80 70 60 50 40 30 20 10 0 up

up

closed

closedartificial

closed

closedartificial

Figure 119

Figure 118 LR (whiteboard )< 5:1 W107

contrast ratio

20 15 S1

10

S3 5

Sav

0 up

closed

closedartificial

Figure 120

Before the analysis of the conclusions it is necessary to mention some parameters that have to be taken into consideration for a critical evaluation of the results. a) Changes in outside conditions (cloud density and orbit of the sun) There are cases where the luminance ratios have to be analysed cautiously due to small changes of the outside conditions. For example, in R203 with louvers in horizontal position, the LR(60Ë&#x161;) is lower than in the one with louvers tilted in 45o (see Figure 112). During the measurements the sky was constantly changing, so, the LR, in a certain level could have been affected. Another 88

3. 5 Visual comfort, Luminance measurements explanation could be that the louvers in horizontal position scatter indirect daylight and this could also affect the general contrast levels in a positive way. However, from the collected data it not clear which theory is right. b) Non realistic conditions in terms of illuminance levels Another parameter of the critical evaluation of the results is that some of the LR do not have realistic interest, due to extremely low illuminance levels. For example the illuminance analysis showed that after a rotation of 45o the need for artificial light is crucial. However, all these measurements are useful for the evaluation of the two different sun shade systems, because it was proved that the different formation in the luminaries in the ceiling, influences the luminance ratios. Therefore, for a direct comparison of the two systems it is necessary to have the same boundary conditions, and the only option is under the influence of daylight. c) Critical or reference view points for the conclusions All the previous Figures (Figure 112-Figure 120) show that in both classrooms the most critical viewpoint is S1, for all the visual fields. Thus, the following conclusions are mainly based on the LR from that point.

Comparison between louvers (R203) and fabric rollers (W107), only under the influence of daylight.

As it was previously explained, for a direct comparison of the two systems it is necessary to have the same boundary conditions. The only option is under the influence of only daylight, as the artificial plan in W107 and R203 is different and affects the LR in way that the result are not comparable. (a) Visual field of 60o Table 23: LR (60o) in R203, daylight.

Table 24: LR (60o) in W107, daylight.

Louvers Fabric rollers Critical point up hor/tal tilted closed up down S1 59:1 37:1 43:1 32:1 S1 45:1 49:1 Sav 54:1 39:1 47:1 26:1 Sav 20:1 45:1 (The LR for all the critical viewpoints in all the different conditions can be found in Appendix F: Table F- 13 - Table F- 24).

Critical point

Table 23 shows that in R203 the LR(60o) with louvers follows a descending tendency, while the fabric rollers in W107 do not seem to make big improvement in preventing glare. Thus, the louvers regulate the LR (60o) efficiently. (b) Visual field of 30o Table 25: LR (30o) in R203, daylight.

Critical point S1 Sav

up 11:1 5:1

Louvers hor/tal tilted 8:1 14:1 2:1 2:1

Table 26: LR (30o) in W107, daylight.

closed 15:1 4:1

Critical point S1 Sav

Fabric rollers up down 32:1 84:1 38:1 12:1

In that case the conclusion if the louvers or the fabrics rollers are better in not clear, as the LR(30o) with the sun shade up is quite different between R203 and W107 this probably happens due to the change of the outside conditions. However, in S1 the LR(30o) has an extremely big rise in the position when the rollers are down, while in R203 the different positions of the louvers at least do not increase significantly the possibility of glare. Thus, even if it not clear, the louvers also seem to regulate the LR (30o) better than the fabric rollers.

89

3.5 Visual comfort, Luminance measurements

(c) Luminance ratios (LR) on the task surface Table 27: LR (whiteboard) in R203, daylight.

Table 28: LR (blackboard) in W107, daylight.

Louvers Fabric rollers Critical point Critical point up horizontal tilted closed up down S1 15:1 9:1 19:1 4:1 S1 6:1 3:1 In that case it is obvious that the fabric rollers (W107) are a better system in blocking the mirroring on a task surface, by putting the rollers down the visibility on the blackboard is immediately improved. In R203 the louvers have to be totally closed in order to reach the LR(task) requirement of 5:1.

Additionally, other useful information derives from a comparison between Table 27 and Table 28.

When the sun shade system is up, (whether this is louvers or rollers), a whiteboard has a LR(task) = 15:1, while a blackboard LR(task) = 6:1, immediately it is clear that blackboards have less glare problem.

Comparison between louvers (R203) and fabric rollers (W107), under the influence of daylight and artificial lighting.

Classroom R203 (Louvers) For preventing discomfort glare in a visual field of 60o there are two possible choices for the position for the louvers: a) Horizontal with daylight: LR(60o) S1= 37:1, LR(60o) Sav= 39:1 (see Appendix F, Table F- 13) b) Tilted with artificial lighting: LR(60o) S1= 43:1, LR(60o) Sav=28:1 (see Appendix F, Table F- 14) In a visual field of 30o all the positions of the louvers in daylight conditions seem to be close to the ratio requirements of 10:1. On the other hand under the influence of the artificial lighting the LR becomes higher exceeding the requirement of 10:1. This implies that the planning of the artificial lighting is problematic.

For preventing indirect glare on the task surface the best position for the louvers is completely closed with artificial light: LR(task) S1= 3:1(see Appendix F, Table F- 18) Classroom W107 (Fabric rollers) For preventing discomfort glare in a visual field of 60o the best position for the rollers is down with daylight: LR(60o) S1= 32:1, LR(60o) Sav= 29:1 (see Appendix F, Table F- 20) In a visual field of 30o all the positions of the rollers (both with daylight and artificial light) seem not able to prevent discomfort glare sensation from the critical viewpoint S1.

For preventing indirect glare on the task surface (blackboard) there are two possible choices for the position for the rollers: a) down with daylight: LR(task) S1= 2:1 (see Appendix F, Table F- 24) b) down with artificial light: LR(task) S1= 3:1 (see Appendix, Table F- 24) Conclusions In general the louvers seem more effective in regulating the general luminance levels, LR(60o)and LR(30o), this can also be verified by a simple view of Figure 122and Figure 126 where it is clear that the louvers create a more homogeneous lighting from the window, while the rollers 'leave' open and unshaded parts of the faรงade. On the other hand, the fabric rollers are better in blocking the mirroring in the board.

90

3. 5 Visual comfort, Luminance measurements In addition, another interesting outcome was that the artificial lighting in R203 needs improvements as in the current conditions it raises the luminance ratios is values beyond the requirements. One of the factors that create this problem is the ceiling in R203 which is lower than in W107, thus the luminaries are part of the visual field in 60o from many view points. Secondly, the formation of the lamps in W107 is perpendicular to the facade (and not parallel like in R203), this make the brightest part of the lamps less visible.

The following pictures (Figure 121 - Figure 124) show the luminance result under the four different positions of the louvers in R203, with artificial lights on.

Figure 121: R203- Louvers up-artificial light -S1

Figure 122: R203-Louvers Tilted 45o- artificial light-S1

Figure 123: R203- Louvers hor./tal-artificial light -S1

Figure 124: R203- Louvers closed-artificial light -S1

The following pictures make more clear the mirroring problems in a TV- screen in G104 (Figure 125 - Figure 128) compared to the blackboard in W107 (Figure 129 - Figure 132).

91

3.5 Visual comfort, Luminance measurements

Figure 125: W107-Rollers up - daylight -S1

Figure 126: W107- rollers down - daylight - S1

Figure 127: Blackboard zoom in (Figure 125)

Figure 128: Blackboard zoom in (Figure 126

Figure 129: G104 -louvers horizontal artificial light S1

Figure 130: G104 - Louvers tilted 45o - artificial -S1

Figure 131: TV screen zoom in (Figure 129)

Figure 132: TV screen zoom in (Figure 130)

92

3.6 Visual comfort, Dialux

3.6 Dialux model For simulating different situations concerning visual comfort, Dialux 4.10 was used. With the help of this program a room with old sunshades and a room with new sunshades could be simulated. If the results of the illuminance levels in the hand measurements resemble the values in the model, the simulation can be used to simulate other conditions.

With Dialux only the illuminance can be correctly simulated. The luminance levels in Figure 133: Results for luminance in R203 in Dialux the windows cannot be seen (see Figure 133). Also mirroring, like in the whiteboard in Figure 134, cannot be simulated well in Dialux.

Because of this restriction in Dialux, the luminance results of the simulation cannot be compared to reality, nor can the contrast ratio be calculated.

Figure 134: Picture with luminance camera of R203

Reflection factors To materialize the rooms in the simulations, photographs were taken with the luminance camera of different parts in the real rooms. This was done for the most important objects in the room like tables, floors, walls and black or whiteboeards.

The program LMK2000 was used to see what the reflection factors of the materials were. For example in Figure 135 a brick wall was photographed. The round part in the figure that is held has a reflection factor of 95.2%. This way the reflection factor of the wall can be put at 30.5% ((52.64*95.2%))/164.2=30.5%).

The complete list of reflection factors used can be found in Appendix F, Table F- 25.

Figure 135: Example of measuring the reflection factor of a brick with a luminance camera

93

3.6 Visual comfort, Dialux Building up the model The measuring points for the simulations were the same as the real measuring points (see Figure 139 and Figure 141). For room W107 with the old sun shading, a LTA value of 0.15 was used for the fabric roller. The rest of the materials used were made, based on the reflection factors that were measured with the luminance camera. Also the outside of the classroom was modelled, because the reflections of the roof and skylights might influence the amount of light coming in (see Figure 138).

Figure 136: Inside Dialux model for room W107 Figure 137: Point for hand measurements

Figure 138: Outside view in Dialux of W107

Figure 139: Placement of measuring points in room W107 in Dialux

For the model of room R203 also the measured reflection factors were used. The outside of the classroom was roughly modelled. The louvers were made according to the specifications of the real louvers. The louvers used are aluminium with a white colour (7040), with a reflectivity of around 54%. The louvers have a width of 80mm and are 0,4mm thick. For both models the same lamps were used as in reality.

Figure 140: Inside Dialux model for room R203

94

Figure 141: Placement of measuring points in room W107 in Dialux

3.6 Visual comfort, Dialux

Figure 143: Louvers on the outside in Dialux of room R203

Figure 142: Outside view in Dialux of R203

Comparison to the hand-measurements In Table 29 and Table 30 the different situations are shown that were simulated. The date and time of these different situations were the same as the hand measurements that were made in the school. This way the values and daylight factors of these two could be compared to validate that the simulation was correct. The overview of the values that were generated by Dialux in all different situations can be found in Appendix F, Table F- 1 to Table F- 12.

Room R203, New sunshade Table 29: Different situations that were simulated in Dialux for room R203

Artificial light off, overcast sky No sunshade Louvers horizontal Louvers 50째 angle Louvers completely closed

Artificial light on, overcast sky No sunshade Louvers horizontal Louvers 50째 angle Louvers completely closed

Room W107, Old sunshade Table 30: Different situations that were simulated in Dialux for room W107

Artificial light off, overcast sky No sunshade Sunshade down

Artificial light on, overcast sky No sunshade Sunshade down

The daylight factor was calculated with the hand measurements that were made. But also from the Dialux simulations the daylight factor could be calculated for each point. In Table 31 and Table 32 the ratio of hand measurement divided by the Dialux daylight factor is show for the different situations. The distribution over the room, of the simulation and the hand measurements, can be seen in Figure 144 to Figure 149. For this points E (next to the window) up to point H (next to the wall) were chosen (see Figure 137). For all comparison graphs, see Appendix E, Figure E- 1 to Figure E- 6.

Table 31: Comparison of the Daylight Factor of the hand measurements with the Dialux values for room R203 Room Nr. R203 R203 R203 R203 R203 R203 R203 R203 Artificial light Off Off Off Off On On On On Sunshade Up Horizontal 50째 Down Up Horizontal 50째 Down Ratio DF 0,88 0,93 1,13 0,24 0,93 0,86 1,72 1,58 hand measure/ Dialux

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3.6 Visual comfort, Dialux Table 32: Comparison of the Daylight Factor of the hand measurements with the Dialux values for room W107 Room Nr. W107 W107 W107 W107 Artificial light Off Off On On Sunshade Up Down Up Down Ration DF 1,16 0,77 1,83 0,74 (handmeasured /Dialux)

R203, Sunshading closed, light off 0,6%

10,0%

0,5%

Daylight factor

Daylight factor

R203, No sunshade, light off 12,0%

8,0% 6,0% 4,0%

0,4% 0,3% 0,2% 0,1%

2,0%

0,0%

0,0% E

F

G

E

H

F

G

H

Measuring point

Measuring point

Measured Daylight Factor

Measured Daylight Factor

Dialux Daylight Factor

Dialux Daylight Factor

Figure 144: Daylight factors for R203, Sunshade up, lights off, comparison Dialux with hand measurements

Figure 145: Daylight factors for R203, Sunshade down, lights off, comparison Dialux with hand measurements

In these figures it is evident that often the curve of the Daylight factor of the simulation is about the same as the real measurements, even though the values are a bit higher or lower in total, especially when there is no sunshade. There are sometimes unusual peaks, like in Figure 147, but this might be because of mistakes in the hand-measurements or differences in exact sunshade angle. Sometimes with artificial light on and with sunshades down there are deviations, which might be due to differences in the exact artificial lighting placement.

R203, Sunshading 50째, light on

14,0%

9,0%

12,0%

8,0%

Daylight factor

Daylight factor

R203, No sunshade, light on

10,0% 8,0% 6,0% 4,0% 2,0%

7,0% 6,0% 5,0% 4,0% 3,0% 2,0% 1,0%

0,0%

0,0% E

F

G

H

E

F

G

H

Measuring point

Measuring point Measured Daylight Factor

Measured Daylight Factor

Dialux Daylight Factor

Dialux Daylight Factor

Figure 146: Daylight factors for R203, Sunshade up, lights on, comparison Dialux with hand measurements

Figure 147: Daylight factors for R203, Sunshade 50째, lights on, comparison Dialux with hand measurements

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3.6 Visual comfort, Dialux

W107, No sunshade, light off

W107, Sunshade closed, light on 6,0%

16,0%

5,0%

Daylight factor

Daylight factor

14,0% 12,0% 10,0% 8,0% 6,0% 4,0%

4,0% 3,0% 2,0% 1,0%

2,0% 0,0%

0,0% E

F

G

Measuring point

H

E

F

G

Measuring point

Measured Daylight Factor

Measured Daylight Factor

Dialux Daylight Factor

Dialux Daylight Factor

Figure 148: Daylight factors for W107, Sunshade up, lights off, comparison Dialux with hand measurements

H

Figure 149: Daylight factors for W107, Sunshade down, lights on, comparison Dialux with hand measurements

Daylight factor comparison As was said before in chapter 5.2.1, the daylight factor should be 3,6% to have 80% of the year enough daylight in the room (between 8:00 and 16:00 oâ&#x20AC;&#x2122;clock). This is only reached for the tables near the window according to the hand measurements, see Figure 150. In these figures the measurement point that met the requirement of 80-100% of the time enough daylight are made green. The points which have 60-80% are made yellow. The graph from which you can derive this percentage, does not go below 60% (see Figure 61). Therefore the red bars in the figures all show 60%, but this might even be much lower than 60% in some cases.

The Dialux values only deviate a little from the hand measurements in two points. When the sunshade is horizontal or tilted there are no tables which get enough light, which means more than 80% of the time enough daylight (see Appendix E, Figure E- 11 to Figure E- 14).

From these graphs it is evident that a good improvement could be to put sensors for different lamps in the room, so that the lamps turn off near the window but turn on further into the room.

This way a lot of energy could be saved.

R203 Dialux, No sunshade % of time enough daylight

% of time enough dayligh

R203 Handmeasurements, No sunshade 100% 80% 60% 40% 20% 0% Zone A Zone B Zone C Zone D

Figure 150: Hand measurements R203, % of time of the year there is enough daylight

100% 80% 60% 40% 20% 0% Zone A Zone B Zone C Zone D

Figure 151: Dialux R203, % of time of the year there is enough daylight

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3.6 Visual comfort, Dialux In W107 there are more tables that get light more than 80% of the time. The Dialux model deviates a little from the hand measurements, with some lower values. When the sunshade is closed no place in the room meets the requirement of more than 80% of the time enough daylight (see Appendix E, Figure E- 15 and Figure E- 16)

W107 Handmeasurements, No sunshade

W107 Dialux, No sunshade 100%

100%

80% 80%

60% 60%

40% 40%

20%

20%

0%

0% Zone A Zone B Zone C Zone D

Figure 152: Hand measurements W107, % of time of the year there is enough daylight

Figure 153: Dialux W107, % of time of the year there is enough daylight

Comparison old and new sunscreen The rooms R203 and W107 that were used for the simulations have different geometries. Therefore the daylight factors for the old and new sunscreen can better be compared to each other, if the shading was on the outside of the same room. This could be done easily in Dialux. The old sun shading was put on room R203, so the daylight factors could be compared to each other.

As can be seen in Figure 154, the daylight factor for the new sunshade in horizontal position is the best, also to get the light further into the room. The old fabric sun shading gives better daylight factors than the tilted and closed position of the sunshade, but further into the room it is almost as bad as the tilted new sunshade.

Daylight factor R203

Daylight factor

2,5% 2,0% 1,5% 1,0% 0,5% 0,0% E

F G H Measuring point Old sunshading down New sunshading horizontal New sunshade tilted

new sunshade down

Figure 154: Comparison of different sunshade positions in room R203 from Dialux

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3.6 Visual comfort, Dialux Simulating extreme conditions To see the illuminance levels during different times of the year, the Dialux model was be used. In this way extreme situations can be shown, especially in combination with the visibility of the black/whiteboard and the smartboard.

22 June was simulated with clear sky, at a moment that the sun is shining directly on the faรงade (at 14:00). This will show extremely high levels for the illuminance values.

For the extremely low illuminance values, 22 December was taken as a reference. This was simulated with an overcast sky, to show this extreme condition, at 9:00 in the morning.

For the situation in between these extremes, the date of 22 March was simulated, in a mixed sky condition. This simulates the condition that is very common in the Netherlands. This was done in the middle of the day at 12:00.

2 things will be taken into consideration in these simulations. First there should be at least 300 lux on the work surface of the students and on the white or blackboard. Secondly a 100 lux maximum on the smartboard is desired, so that students can see the beamer or TV-screen well.

The results from the simulations have been put into appendix F (Table F- 26 to Table F- 31).

The results from the simulations confirm what has been said in the previous chapter of the illuminance hand measurements. It is impossible to see the smartboards well without compromising the illuminance levels on the work plane. Even in other situations throughout the year this remains the same problem. Again, the solution might be to install stronger beamers, so the illuminance values can be higher than 100 lux near the board.

For the visibility of the white or blackboard, down positions is not good, even with artificial light on. Because the lighting is not sufficient in many cases, for the corners of the rooms, the solutions might be to put stronger lamps in the rooms. Now there is twice 36Watts used per lamp (see Appendix E, Figure E- 17 and Figure E- 18 for the artificial lighting plans).

In the simulations it is also apparent that the visibility in R203 is not sufficient in winter when the artificial light is on, even with the sunshade in the up position. In W107 it is sufficient. This is probably because it has a higher ceiling. Also it has a different lighting plan, in R203 the lamps are parallel to the faรงade, and in W107 the lamps are perpendicular to the faรงade.

To see the smartboards well, in summer and spring the sunshades need to be down completely, but in winter the smartboard is visible without sunshade. But again the problem rises that the children cannot see their own work surface well. This means that another solution is needed, to be able to see the smartboards well, while the children are still able to see their own desks.

Improvements As an improvement, the walls which are now brick were made white in Dialux. This was done to try to make the light go in the room further, and spread more evenly.

Changing the colours of the walls and floors doe not raise the illuminance levels significantly; neither does it help a lot with the distribution across the room (see Figure 155 and Figure 156).

Before the adjustment, neither the blackboard nor the smartboard met the requirements. This did not change after the adjustment.

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3.6 Visual comfort, Dialux

R203, sunshading 50째,(no artificial light)

R203, sunshading 50째, (no artificial light) improvement 400

400 350 300 250 200 150 100 50 0

350 300 250 200 150 100

Lux

50 0

Lux

Zone A Zone B Zone C Zone D Measurement points

Figure 155: Room R203 in Dialux, 22 March 12:00, sun shading 50째, no artificial light, illuminance values

Zone A Zone B Zone Zone C D Measurement points

Figure 156: Room R203 improved by white walls and floor in Dialux, 22 March 12:00, sun shading 50째, no artificial light, illuminance levels

Discussion In many situations, the Dialux model matched the hand measurements relatively well. But in some situations, especially with the artificial light on, or with the sunshade closed, the values differed more. This could be because the artificial light scheme was not correctly simulated in Dialux, for example the exact placement of the luminaries might have been wrong. Also the exact angle of the louvers might have been wrong in Dialux, because it was very difficult to know the exact angle of them during the hand measurements.

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3.7 Visual comfort, conclusions

3.7 Visual comfort conclusions Before discussing the main research question, a brief overview of the sub questions related to the visual comfort is given.

1. What are the illuminance levels in the classrooms in different sunshade positions, for the new and old sunshade?

In the illuminance measurements, W107 represents the old fabric rollers, while G104 the new shading system. In both rooms the daylight is unevenly distributed, especially in zone C and D (see Figure 64).

Under daylight conditions of an overcast sky, the illuminance levels are low for zone C and D, even when the sun shade is up. Thus, for all the shading positions up, horizontal or tilted (similarly for fabric rollers) daylight factors in all classrooms are below the requirements.

1.1How much of the time is artificial light needed, also when using the sun shading?

The use of artificial lighting is necessary in both rooms with louvers and rollers as the daylight factors are pretty low.

Unexpectedly, even under the influence of artificial lights the problem of the unevenly illuminance distribution in zone A and zone D can't be solved, which leads to the conclusion that the planning of luminaries of the room is not efficient.

Only near the window without sunshade, there is enough daylight for 80% of the year. With all other types of sunshading these values are a lot lower than 80% in the entire room.

2. What is the general luminance levels in the classrooms in different sunshade positions, for the new and old sunshade?

The term 'general luminance levels' implies the luminance ratio in a visual field of 60o which has to be below a ratio 30:1 for preventing discomfort glare.

The louvers regulate the LR(60o) more efficiently than the fabric rollers. From the view of the rollers the problems is that they leave relatively big unshaded parts in the faรงade which eventually concludes to higher discomfort sensation. On the other hand the new sun shading system creates a more homogeneous lighting from the window, while at the same time the indirect light is scattered in the room through the ceiling. However, this scattering mechanism works well only in the horizontal position of the louvers, beyond that the light levels drop significantly, meaning that until all the bright strips have disappeared the LR cannot reach the requirements.

3. What is the influence of the positions of the sunscreens (old and new) on the visibility of whiteboard/ blackboard, TV-screen and smart board ?

The visibility of a vertical task (whiteboard/ blackboard, TV-screen and smart board) is related to three parameters: (a) the illuminance levels, (b) the contrast ratio in an area close to the task (visual filed of 30o), (c) the contrast ratio of the task surface itself (indirect glare, mirroring of bright sources).

For the whiteboards/blackboards and the TV-screen the main visibility problems are due to discomfort glare. The physical mechanism that creates these glare problems is the same for all these three surfaces, although they have different glossiness which means that the mirroring problem has different intensity for every one of these surfaces.

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4.1 General conclusions From that point of view the TV-screens have the worst mirroring problems, while a comparison between whiteboards and blackboards showed that the first ones have less visual problems. So, if it is possible the blackboard is a better choice.

Concerning the question which sun shade systems is more efficient in preventing mirroring and glare sensation around the task, the answer is ambiguous. The problem is that according to our approach there are two luminance ratios that determine the good visibility on a task surface.

The louvers seem to regulate the LR(30o) around the task better than the fabric rollers, while the exact opposite happens for the LR on the surface of the task. However, in the hierarchy of importance, the prevention of the mirroring is higher, so, the rollers seem to be a better sun shade system for that purpose.

The parameters that affect the visibility in TV-screens and smartboards are different and its visual problems are not related to indirect glare but to the requirement of lower lux levels in order to be visible. If the case is which sun shade system has the ability to minimize the lux levels without the influence of another system (interior curtains etc) then the louvers is the only choice that meet such a requirement.

However, the problem is the requirement of lower lux levels, so that the smartboard is visible, is a factor that deteriorates the visual performance for other tasks such as reading and writing.

Even though smart boards and TV screens have different visibility problems, at the end for both, the users are forced to minimize the influence of the daylight, concluding to extensive use of artificial light. Thus, they solve the problem in way that from an economic and sustainable perspective is not profitable for the energy performance of the building.

4. What is the influence of the sunscreens on the illuminance levels in extreme situations? (This can be answered with computer simulations.

The values of the simulation are quite similar to the hand measurement in the situations with sunshades up, which means the room is modelled correctly. Also with sunshading the Dialux is similar to the measurements, except for the louvers in the completely down position. Some differences when the sunshades are down are probably due to changing conditions during the hand measurements, which caused fluctuations in the daylight factor. Mostly there is the same curve in the graphs, but sometimes they have lower or higher values. For artificial light on, the differences might be due to slight differences in placements of the lamps in the simulations.

When comparing the different sun shading and sunshade positions concerning the illuminance, the horizontal position is the best, also to let the light go further into the room. The old sun shading gives better daylight factors than the new sunshade with tilted and closed position.

In terms of illuminance levels, in extreme conditions in summer, spring and winter there is no sunshade position which allows the smartboard to be seen well,. Also the blackboard cannot be seen well in the winter, or in some sunshade positions. An improvement could be to install brighter lights in the room. Also an improvement could be to get beamers that produce more light, so that the illuminance does not need to be so low in the classroom. Also sensors in the lamp fittings could be an option, so that energy can be saved in the lamps near the windows.

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4. Conclusions and Recommendations

4. Conclusions and Recommendations 4.1 General conclusions With the sub questions the main question can be answered. The main question of this research was: What is the effect of the new sun shading system of the Gertrudis School on the thermal comfort, visual comfort and the indoor air quality in the classrooms, compared to the existing sunshading?

Thermal comfort The conclusions for the effect of the two different sun shading systems are based on two methods: a) The analysis of the recorded temperature data from the loggers in combination with additional information about the position of the shading systems. b) Capsol simulations which verified some preliminary conclusions enlightening some aspects that weren't obvious because the measurements took place in a limited time period of two weeks.

During the warmest school period (September, May and June) the outcome was that both systems prevent the biggest part of the unwanted solar gain. Although the new shading system regulates the indoor temperature in a more efficient way, especially during June, this improvement is not the same for all the rooms.

Specifically, for a standard room with western facade (G104, R203) both systems prevent the rise of the temperature above 26째C to be higher than10% of the total occupant time. However, when using louvers for the three warmest months between 08:00-16:00, the amount of hours that exceed 26째C drop even more to 4.0% for G104 and to 5.4% for R203.

In R205 though, the room with the two facades, the new shading is much more effective than the old one, as the percentage of the hours that exceed 26째C using fabric roller is quite high (12.1%), while using louver drops to 6.0%.

In R209, there is also a small, improvement by using rollers, but both systems fail to regulate the indoor temperature in a way that it does not exceed 26째C for less than 10% of the total occupant time. Thus, it seems that in the rooms with east orientation the new sun shading system do not make significant difference.

The reason behind that is that the rooms with east orientation warm up faster than the other ones and under the influence of the high internal heat load due to occupancy, they present higher average indoor temperature between 08:00 and 16:00, having bigger thermal discomfort problems during the warmer months of May and June. Therefore, the heat removal from the occupancy becomes the main problem for the east rooms, and by blocking unwanted solar radiation the problem cannot be solved. Thus, it seems that in the rooms with western orientation the new sun shading system do not make significant difference.

Relative humidity The relative humidity is relatively high in all rooms, and sometimes exceeds the maximum requirement. This might be due to low refreshment rates. If the different sunshade systems influence the velocity rate, this might also influence the relative humidity in the rooms. But no conclusions could be made for the difference in refreshment rates between the old and new sunshade system.

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4. Conclusions and Recommendations Indoor air quality The air quality is often insufficient in the classrooms; there are many complaints about musty air and draught. The CO2 levels were too high in an occupied room in all measured situations with occupants. This is attributed to the fact that more than 3 windows should be open to lower the CO2 levels, but this might cause draught. Similarly to the relative humidity, no significant influence due to different sun shading system has been verified.

Flexibility The new sunscreen has the advantage that it can be manually controlled for each classroom individually, in contrary to the old sunscreen. The sunscreens were manually controlled a lot, especially in the room with two external faรงades, where they are often more closed. This is probably due to visual discomfort in that room.

Illuminance levels Both two systems do not prevent unevenly distributed illuminance levels. Both systems for all the shading positions up, horizontal or tilted (similarly for fabric rollers) render daylight factors, in all the possible positions in a classroom, which are below the requirements. The only exception is the zone near the window without any sunshade. In that case there is enough daylight for 80% of the year. Especially in zones which are further from the facade even when the shading system is not used, the daylight factors are significantly low.

Therefore, the use of artificial lighting is necessary independently of the shading system.

Unexpectedly, even under the influence of artificial lights the problem of the unevenly illuminance distribution can't be solved, which leads to the conclusion that the planning of luminaries of the room is not efficient.

Discomfort glare in a visual field of 60o The louvers regulate the general contrast levels, LR (60o), more efficiently than the fabric rollers.

The louvers create a more homogeneous lighting from the window while at the same time the indirect light is scattered in the room through the ceiling. However this scattering mechanism works well only with louvers in a horizontal position, beyond that there is significant reduction in the illuminance levels. On the other hand problem with the fabric rollers is that they leave relatively big unshaded parts in the faรงade, which eventually concludes to higher discomfort sensation.

Vertical task visibility (whiteboard, blackboard, TV-screens) Concerning the question which sun shade systems is more efficient in regulating the daylight in order to have good visibility on a vertical task surface, the answer is ambiguous. The problem is that according to our approach there are three parameters that determine the vertical task visibility; the illuminance levels, the glare sensation around the task and the mirroring (or indirect discomfort glare). For the first parameter both systems have similar behaviour. However, the louvers regulate the LR (30o) around the task better than the fabric rollers, while for blocking the mirroring they have to be almost closed, minimizing the daylight illuminance levels. On the contrary, the fabric rollers are able to block the mirroring letting in more daylight.

Assuming that in the hierarchy of importance, the prevention of the mirroring is higher, then the fabric roller is a better sun shade system for blocking the indirect glare on the surface of a blackboard or a whiteboard.

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4. Conclusions and recommendations Critical evaluation of the effect of the horizontal louvers in terms of thermal and visual performance Even though the louvers have a better performance in terms of thermal comfort, it seems that it has a negative effect on the incoming light. Especially, in the western facades in order to prevent the overheating, the louvers have to be almost closed.

Additionally, concerning the visual comfort, it has been proved that with a mixed sky, in a common scenario the louvers are able to regulate the luminance levels in comfort levels in a more closed configuration, blocking even more daylight. However, when the louvers are in a horizontal configuration they disperse daylight, regulating the luminance levels, but this happens only in case of relatively low outside illuminance levels.

Thus, there are two aspects that have to be investigated. Firstly, if there is another system with louvers that can disperse indirect light more effectively in a closed configuration, increasing the incoming daylight without causing glare. Secondly, if another type like vertical louvers could increase the daylight, resulting in the same thermal comfort without the necessity to be totally closed when the sun is very low.

4.2 Recommendations In order to make the tutors aware of optimal usage of the new system in particular situations, they should be informed about general conclusions of this report concerning visual comfort. Especially, related to the use of the system concerning the modern schoolboards.

Replacement of old sun shade in rooms with east orientation Although louvers regulate the indoor temperature in a more efficient way, this benefit is significantly smaller in rooms with western orientation. Thus for the thermal comfort in western rooms louvers and rollers are almost equal.

However, visual discomfort is even more important in order to be able to work with modern education equipment. This is why the new system, with a de-central control, is a big improvement compared to the fabric rollers which do not have a manual control. Currently, tutors in east orientated rooms canâ&#x20AC;&#x2122;t adjust the conditions in their rooms, and since east rooms are exposed to direct sun in the mornings, it is very likely that this will limit the tutors in their daily work.

Optimization of the new sun shade system a) Interior curtains At wind speeds of more than 12m/s, the new sunshade system goes up for an hour in order to prevent damage. It did happen a few times during our measurements, and during sunny days it will cause (visual and thermal) discomfort for the students. Therefore it would be useful to maintain the existing interior louvers.

Additionally, the interior curtains can improve of the u-value of the facade; something crucial especially for the winter, as the classrooms have extremely big heat loses b) Dynamic regulation of the louvers Except of minimizing the heat losses, another aspect is to take advantage of solar load which is beneficial. It was observed that the louvers are down even when there is not any direct radiation on the facades having a relatively low threshold of activation close to 150W of global radiation.

Thus, there two ways to address the problem: Firstly, the central activation of the louvers should not be stable during the year, but it needs to take into consideration the indoor temperature, as in some cases the heat gain is necessary, especially in a building which is not air tight and has low insulation.

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4. Conclusions and Recommendations Secondly, if it not possible to activate the louvers in a central system that calculates the comfort indoor temperature, then the users should manually control the system whenever they feel that the room temperature is comfortable and the glare is not an issue. Thus, the visual comfort as the main criterion from the side of the user can help to optimize the sun shading also in thermal aspects.

Whiteboard or Blackboard A comparison between whiteboards and blackboards showed that the first ones have less mirroring problems. So, when it is possible the blackboard is a better choice.

Smartboard or TV-screen These two multimedia means have completely different visibility problems. So, the choice is not always clear and it has to do with the priorities of the user.

For TV-screens the main problem is indirect glare (mirroring), while for smartboards, the requirement of low illuminance levels, deteriorating the visual performance of the pupils in other tasks such as reading and writing.

The existing TV-screens and beamers in the school present problematic visibility. But both of them can be improved. â&#x20AC;˘ Using new TV-screens with mat surface would improve the visibility substantially from many positions in the classroom. â&#x20AC;˘ Stronger beamers would allow higher surrounding illuminance levels.

The energy usage of the beamers/TV-screens would be a crucial criterion for the final choice. Such a calculation should take into consideration the energy consumption from the artificial lights.

Thus, firstly it is necessary to estimate the position of the louvers in which the mirroring is prevented and then see the necessity for artificial light. Similarly for the beamers, in order to figure out the energy consumption of the artificial light.

Artificial light To save energy, the artificial light could be automatically controlled. The daylight factors near the window are sufficient; while further into the room they are too low. This way energy can be saved by automatically turning off the lights nearer the window.

For bad visibility on the blackboards and the corners of the room the lighting can be replaced to have a higher efficiency.

Ventilation (as a mean of heat removal and air refreshment) Besides, during the investigations on thermal comfort, the onsite measurements showed very high CO2-levels causing dissatisfaction of the pupils, a situation that can be prevented when tutors open windows and doors more often, especially in between lessons, when the students are not in the room and will not experience draught.

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5. Appendix A

5. Appendices Appendix A: Survey

.

Figure A- 1: Longitudinal survey, handed out to the teachers

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5. Appendix B

Figure A- 2: Questionnaire for students, thermal comfort

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5. Appendix A

Figure A- 3: Questionnaire for students, visual comfort

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5. Appendix B

Temperaturepreference

2 1 0 21,5

22

22,5

23

23,5

24

-1 -2 Temperature

Temperature preferable: 1 Colder 0 No change -1 Warmer Figure A- 4: Survey results: Temperature preference correlated with temperature, with regression line

Temperature experience

3 2 1 0 21,5 -1

22

22,5

23

23,5

24

-2 -3

Temperature 2 Too cold 1 Comfortable cold 0 Comfortable -1 Comfortable warm -2 Tooâ&#x20AC;Ś

Figure A- 5: Survey results: Temperature experience correlated with temperature, with regression line

Figure A- 6: Zones made to analyze results of the survey

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5. Appendix B

Appendix B: Figures of thermal comfort analysis and Capsol simulation 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0

Pupils

28 26 24 22 20 18 16 14 12 10 8 6 4 2 0

Pupils

Pupils present (R205)

Room temperature (째C)

24,0 22,0 20,0 18,0 16,0 14,0 12,0 10,0 8,0

pupils present

Lesson turn

Room temperature

Outside temperature

Figure B- 1: R205 week 40, temperatures against occupancy of the room

Room temperature (째C)

Pupils present (G104) 24,0 22,0 20,0 18,0 16,0 14,0 12,0 10,0 8,0

pupils present

Lesson turn

Room temperature

Outside temperature

Figure B- 2: G104 week 40, temperatures against the occupancy of the room

Room temperature (째C)

Ventilation rates R209 12

24,0

10

22,0 20,0

8

18,0 16,0

6

14,0

4

12,0

2

10,0 8,0

0

Ventilation rate

Lesson turn

Outside temperature

Figure B- 3: Assumed refreshment rates for R209 in week 39

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Room temperature

5. Appendix B

Pupils present (R209) (week40) 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0

24,0

Room temperature (째C)

22,0 20,0 18,0 16,0 14,0 12,0 10,0 8,0 8:00

14:00

pupils present

Lesson turn

Room temperature

Outside temperature

Figure B- 4: Friday 5-10-2012, room R209, lesson turns with inside and outside temperature

Capsol simulation

Figure B- 5: Outside temperature reference in Capsol for weeks 39 and 40, as used for the calibration of the model.

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5. Appendix B

Figure B- 6: Global solar radiation in Capsol for weeks 39 and 40, as used for the calibration of the model.

Figure B- 7: Diffuse solar radiation in Capsol for weeks 39 and 40.

Figure B- 8: Direct solar radiation in Capsol for weeks 39 and 40.

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5. Appendix B

Figure B- 9:Temperature zones

Figure B- 10: Ventilation zones

Figure B- 11: Function references

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5. Appendix B

Figure B- 12: Geometry input G104, R203, R209.

Figure B- 13: Geometry input, R205.

Figure B- 14: Controls in G104, R203, R209.

Figure B- 15: Controls in R205.

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5. Appendix B

Figure B- 16: Materials used in the external faรงade of the classrooms

Figure B- 17: Materials used to simulate the different properties of the concrete slabs.

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5. Appendix B

Figure B- 18: Materials used to simulate the side brick walls of the classrooms.

Figure B- 19: Materials that simulate the two sun shading systems, louvers and fabric rollers.

Figure B- 20: The material used as sensor for the activation of the sun shading.

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5. Appendix B

Figure B- 21: The material used for the simulation of the internal curtains in R205.

Figure B- 22: Internal heat reference of G104, week 39.

Figure B- 23: Internal heat reference of G104, week 40.

Figure B- 24: Internal heat reference of R203, week 39.

118

5. Appendix B

Figure B- 25: Internal heat reference of R203, week 40.

Figure B- 26: Internal heat reference of R209, week 39.

Figure B- 27: Internal heat reference of R209, week 40.

Figure B- 28: Ventilation rate reference of G104, week 39.

119

5. Appendix B

Figure B- 29: Ventilation reference of G104, week 40.

Figure B- 30: Ventilation reference of R203, week 39.

Figure B- 31: Ventilation reference of R203, week 40.

120

5. Appendix B

Figure B- 32: Ventilation reference of R209, week 39.

Figure B- 33: Ventilation reference of R209, week 40.

Figure B- 34: Capsol temperature graph of the calibration of G104, during week 39-40.

121

5. Appendix B

Figure B- 35: Capsol temperature graph of the calibration of R205, during week 39-40.

Figure B- 36: Internal heat reference used in the comparison of the two shading systems.

122

5. Appendix B

Figure B- 37: Ventilation reference used in the comparison of the two shading systems.

123

5. Appendix B

G104 May 31 29 27 25 23

T [째C]

21 19 17 15 13 11 9

T_out

G104_May_Louvers

G104_May_Rollers

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

7 G104_May_no sun shading

Figure B- 38: Comparison of the affect of the different sun shading systems in the indoor temperature of G104, during May (Climate conditions De Bilt, 1964).

G104 June 33 31 29 27 25 23 T [째C]

21 19 17 15 13 11 9

T_out

G104_Jun_Louvers

G104_Jun_Rollers

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

7

G104_Jun_no sun shade

Figure B- 39: Comparison of the affect of the different sun shading systems in the indoor temperature of G104, during June (Climate conditions De Bilt, 1964).

124

5. Appendix B

G104 Sep 31 29 27 25 23

T [째C]

21 19 17 15 13 11 9

T_out

G104_Sep_Louvers

G104_Sep_Rollers

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

7 G104_Sep_No sun shade

Figure B- 40: Comparison of the affect of the different sun shading systems in the indoor temperature of G104, during September (Climate conditions De Bilt,1964).

R209 May 31 29 27 25 23

T [째C]

21 19 17 15 13 11

T_out

R209_May_Louvers

R209_May_Rollers

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

7

24

9

R209_May_no sun shading

Figure B- 41: Comparison of the affect of the different sun shading systems in the indoor temperature of R209, during May (Climate conditions De Bilt, 1964).

125

5. Appendix B

R209 June 35 33 31 29 27 25 T [째C]

23 21 19 17 15 13 11 9

T_out

R209_Jun_Louvers

R209_Jun_Rollers

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

7 R209_Jun_no sun shade

Figure B- 42: Comparison of the affect of the different sun shading systems in the indoor temperature of R209, during June (Climate conditions De Bilt, 1964).

R209 Sep 29 27 25 23

T [째C]

21 19 17 15 13 11 9

T_out

R209_Sep_Louvers

R209_Sep_Rollers

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

24

7 R209_Sep_No sun shade

Figure B- 43: Comparison of the affect of the different sun shading systems in the indoor temperature of R209, during September (Climate conditions De Bilt, 1964).

126

5. Appendix C

Appendix C: Tables thermal comfort Table C- 1: Velocities for G104 for different sunshade positions, in the lower windows

Angle of louvers No louvers Horizontal 45째 Vertical

Nr.1 min (m/s) 0,25 0,5 0,2 0,3

Nr. 1 (m/s) 3,2 4 2,95 2,7

max Nr. 3 (m/s) 0,25 0,7 0,31 0,5

min Nr. 3 (m/s) 3,25 2,3 2,1 1,9

max Average both windows 1,74 1,88 1,5 1,35

Table C- 2: Velocities for G104 for different sunshade positions, in the upper windows

Angle of Nr.2 min (m/s) louvers

Nr. 2 (m/s)

No louvers Horizontal 45째 Vertical

1,1 3,7 3,05 2,05

0,46 0,33 0,5 0,32

max Nr. 4 (m/s)

min Nr. 4 (m/s)

0,65 0,75 0,25 0,4

2,37 3,9 0,9 2,2

max Average both windows (m/s) 1,15 2,17 1,18 1,24

Table C- 3: Velocities for W107 for different sunshade positions, in the lower windows

Angle of Nr.1 min (m/s) louvers

Nr. 1 (m/s)

max Nr. 3 (m/s)

min Nr. 3 (m/s)

No shading Sunshade down

0,12

0,75

0,09

0,97

0,18

1,47

0,14

0,87

max Average both windows (m/s) 0,48 0,67

Table C- 4: Difference for velocities between open and closed door for W107

Door is

Nr.1 min (m/s)

Nr. 1 (m/s)

Open Closed

0,23 0,15

0,78 1,35

max Nr. 3 (m/s) 0,08 0,25

min Nr. 3 (m/s) 0,65 0,42

max Average both windows (m/s) 0,42 0,54

Table C- 5: Velocities for W107 for different sunshade positions, in the upper windows

Angle of Nr 2 min (m/s) louvers No shading Sunshade down

Nr. 2 (m/s)

max Nr. 4 (m/s)

min Nr. 4 (m/s)

0,09

0,34

0,26

0,35

0,22

0,35

0,01

0,45

127

max Average both windows (m/s) 0,26 0,26

5. Appendix C

Table C- 6: Assumed refreshment rates for different situations of opened doors and windows

Windows open 0 0 1 1 2 2 3 3 4 4 5 5

Door open 0 1 0 1 0 1 0 1 0 1 0 1

Assumed refreshment rate 0,5 0,5 1,5 3 3 6 4,5 9 6 10 7,5 10

128

5. Appendix D

Appendix D: Hand measurements

Figure D- 1: Hand measurements in G104, on 19/9/2012

Figure D- 2: Hand measurements in W107 on 19/9/2012

129

5. Appendix E

Appendix E: Figures visual comfort Daylight factor R203, Sunshading 45째, light off

3,0%

1,4%

2,5%

1,2%

Daylight factor

Daylight factor

Daylight factor R203, Sunshading horizontal, light off

2,0% 1,5% 1,0% 0,5% 0,0%

1,0% 0,8% 0,6% 0,4% 0,2% 0,0%

E

F

G

H

E

Measuring point

F

G

H

Measuring point

Measured Daylight Factor Measured Daylight Factor Dialux Daylight Factor

Dialux Daylight Factor

Figure E- 1: Comparison daylight factor of hand measurements and Dialux, room R203

Figure E- 2: Comparison daylight factor of hand measurements and Dialux, room R203

Daylight factor R203, Sunshading down, light on

Daylight factor R203, Sunshading horizontal, light on

6,0%

Daylight factor

Daylight factor

7,0%

5,0% 4,0% 3,0% 2,0% 1,0% 0,0% E

F

G

5,0% 4,5% 4,0% 3,5% 3,0% 2,5% 2,0% 1,5% 1,0% 0,5% 0,0% E

H

F

G

Measuring point

Measuring point

Measured Daylight Factor

Measured Daylight Factor

Dialux Daylight Factor

Dialux Daylight Factor

Figure E- 3: Comparison daylight factor of hand measurements and Dialux, room R203

H

Figure E- 4: Comparison daylight factor of hand measurements and Dialux, room R203

130

Daylight factor W107, Sunshading down, light off

Daylight factor W107, Sunshading up, light on

3,0%

18,0% 16,0% 14,0% 12,0% 10,0% 8,0% 6,0% 4,0% 2,0% 0,0%

2,5%

Daylight factor

Daylight factor

5. Appendix E

2,0% 1,5% 1,0% 0,5% 0,0% E

F

G

H

E

Measuring point

G

Measured Daylight Factor

Measured Daylight Factor

Dialux Daylight Factor

Dialux Daylight Factor

Figure E- 6: Comparison daylight factor of hand measurements and Dialux, room W107

Artificial and sunscreen (G104) 4

Artificial light/position suncreen

4

3

2

1

0 Thu. 8:00 16:00 09/20 24:00 Artificial light (2=on)

Fri. 09/21 24:00

8:00

H

Measuring point

Figure E- 5: Comparison daylight factor of hand measurements and Dialux, room W107

Artificial light/position suncreen

F

16:00

Sat. 09/22 24:00

Position sunscreen (1=up, 2=lamels horizontal, 3=lamels tilted, 4=lamels vertical)

Figure E- 7: Room G104 week 39, artificial light and sunscreen

Artificial light and sunscreen (G104)

3

2

1

0 Mon. 6:00 12:00 18:00 Tu. 6:00 12:00 18:00 Wed. 09/24 09/25 26/12 24:00 24:00 24:00 Artificial light (2=on) Position sunscreen (1=up, 2=lamels horizontal, 3=lamels tilted, 4=lamels vertical)

Figure E- 8: Room G104 week 39, artificial light and sunscreen

131

5. Appendix E

Artificial light and sunscreen (R209) Global/direct radiation (W/m2)

2,5

2

1,5

1

0,5

0 Mon. 09/24 24:00

8:00

16:00

Tu. 09/25 24:00

8:00

16:00

Wed. 26/12 24:00

8:00

Artificial light (2=on)

16:00

Thu. 09/27 24:00

8:00

16:00

Fri. 09/28 24:00

8:00

16:00

Sat. 09/29 24:00

Fabric roller down (2=yes)

Figure E- 9: Room R209 week 39, artificial light and old sunscreen

Artificial light and sunscreen (R205) 2

4

Artificial light

Position sunscreens

5

3

1 2

1

0 0 Mon. 6:00 12:00 18:00 Tu. 6:00 12:00 18:00 Wed. 6:00 12:00 18:00 Thu. 6:00 12:00 18:00 Fri. 6:00 12:00 18:00 Sat. 09/24 09/25 26/12 09/27 09/28 09/29 24:00 24:00 24:00 24:00 24:00 24:00 Artificial light (2=on) Position West sunscreen (1=up, 2=lamels horizontal, 3=lamels tilted, 4=lamels vertical) Position South sunscreen

Figure E- 10: Room R205 week 39, artificial light and new sunscreen position

132

5. Appendix E

R203 Handmeasurements, Horizontal sunshade % of time enough daylight (no artificial light)

R203 Dialux, Horizontal sunshade % of time enough daylight (no artificial light) 100%

100%

80%

80%

60%

60% 40%

40% 20%

20%

0%

0% Zone A Zone B Zone C Zone D

Figure E- 11: Hand measurements R203, horizontal sunshade, % of time of the year there is enough daylight

Figure E- 12: Dialux R203, horizontal sunshade, % of time of the year there is enough daylight,

R203 Handmeasurements, Sunshade 50째 % of time enough daylight (no artificial light)

R203 Handmeasurements, Sunshade 50째 % of time enough daylight (no artificial light) 100%

100%

80%

80%

60%

60%

40%

40%

20%

20%

0%

0%

Figure E- 13: Hand measurements R203, sunshade tilted, % of time of the year there is enough daylight

Figure E- 14: Dialux R203, sunshade tilted, % of time of the year there is enough daylight

133

5. Appendix E

W107 Handmeasurements, Sunshade down % of time enough daylight (no artificial light)

W107 Dialux, Sunshade down % of time enough daylight (no artificial light) 100%

100%

80%

80%

60%

60% 40%

40%

20%

20% Zone A Zone B Zone C Zone D

Zone D

Zone C

0% Zone B

Zone A

0%

Figure E- 15: Hand measurements W107, sunshade down, % of time of the year there is enough daylight

Figure E- 16: Dialux R203, sunshade down, % of time of the year there is enough daylight

Figure E- 17: Artificial lighting plan for room R203 (in Dialux)

Figure E- 18: Artificial lighting plan for W107 (in Dialux)

134

5. Appendix F

Appendix F: Tables visual comfort Table F- 1: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room R203 on 6 October 2012, 10:45, sunshading up, artificial light off

Table F- 2: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room R203 on 6 October 2012, 11:20, sunshading down, artificial light off

135

5. Appendix F Table F- 3: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room R203 on 6 October 2012, 11:00, sunshading horizontal, artificial light off

Table F- 4: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room R203 on 6 October 2012, 11:14, sunshading 50 degrees, artificial light off

136

5. Appendix F Table F- 5: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room R203 on 6 October 2012, 10:54, sunshading up, artificial light on

Table F- 6: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room R203 on 6 October 2012, 11:31, sunshading down, artificial light on

137

5. Appendix F Table F- 7: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room R203 on 6 October 2012, 11:09, sunshading horizontal, artificial light on

Table F- 8: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room R203 on 6 October 2012, 11:20, sunshading 50 degrees, artificial light on

138

5. Appendix F Table F- 9: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room W107 on 6 October 2012, 11:59, sunshading up, artificial light off

Table F- 10: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room W107 on 6 October 2012, 12:28, sunshading down, artificial light off

139

5. Appendix F Table F- 11: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room W107 on 6 October 2012, 12:06, sunshading up, artificial light on

Table F- 12: Results of handmeasurements and Dialux values for illuminance and daylight factors, Room W107 on 6 October 2012, 12:37, sunshading down, artificial light on

140

5. Appendix F Table F- 13: Luminance ratios in visual field of 60o, R203, Daylight Position S1 S2 S3 S4 of louvers up 59:1 60:1 24:1 12:1 horizontal 37:1 31:1 16:1 8:1 o tilted 45 43:1 49:1 16:1 9:1 closed 32:1 35:1 11:1 7:1

Sav

T1

54:1 39:1 47:1 26:1

50:1 61:1 43:1

Table F- 14: Luminance ratios in visual field of 60o, R203, Daylight and artificial lighting Position S1 S2 S3 S4 Sav of louvers up 46:1 42:1 33:1 12:1 54:1 horizontal 50:1 47:1 21:1 48:1 tilted 45o 43:1 29:1 30:1 28:1 closed 13:1 6:1 2:1 6:1 Table F- 15: Luminance ratios in visual field of 30o, R203, Daylight Position S1 S2 S3 S4 of louvers up 11:1 3:1 6:1 9:1 horizontal 8:1 2:1 3:1 3:1 tilted 45o 14:1 2:1 3:1 2:1 closed 15:1 3:1 4:1 4:1

Sav 5:1 2:1 2:1 4:1

Table F- 16: Luminance ratios in visual field of 30o, R203, Daylight and artificial lighting Position S1 S2 S3 S4 Sav of louvers up 11:1 3:1 6:1 9:1 5:1 horizontal 8:1 2:1 3:1 3:1 2:1 tilted 45o 14:1 2:1 3:1 2:1 2:1 closed 15:1 3:1 4:1 4:1 4:1 Table F- 17: Luminance ratios in whiteboard, R203, Daylight Position S1 S2 S3 of louvers up 15:1 9:1 2:1 horizontal 9:1 6:1 2:1 tilted 45o 19:1 5:1 2:1 closed 4:1 3:1 2:1

S4

Sav

2:1 2:1 2:1 2:1

2:1 2:1 2:1 3:1

Table F- 18: Luminance ratios in whiteboard, R203, Daylight and artificial lighting Position S1 S2 S3 S4 Sav of louvers up 16:1 7:1 2:1 2:1 2:1 horizontal 23:1 7:1 2:1 2:1 tilted 45o 15:1 4:1 2:1 2:1 closed 3:1 2:1 2:1 3:1 Table F- 19: Luminance ratios in visual field of 60o, W107, Daylight

141

T1 35:1 47:1 13:1 4:1

5. Appendix F Position of louvers up down

S1

S2

45:1 49:1

S3

S4

12:1 16:1

Sav 20:1 45:1

Table F- 20: Luminance ratios in visual field of 60o, W107, Daylight and artificial lighting Position S1 S2 S3 S4 Sav of louvers up 66:1 32:1 59:1 down 32:1 20:1 29:1 Table F- 21: Luminance ratios in visual field of 30o, W107, Daylight Position S1 S2 S3 S4 of louvers up 32:1 47:1 down 84:1 12:1

Sav 38:1 12:1

Table F- 22: Luminance ratios in visual field of 30o, W107, Daylight and artificial lighting Position S1 S2 S3 S4 Sav of louvers up 32:1 11:1 7:1 down 78:1 13:1 11:1 Table F- 23: Luminance ratios in blackboard, W107, Daylight Position S1 S2 S3 of louvers up 6:1 3:1 down 3:1 3:1

S4

Sav 4:1 3:1

Table F- 24: Luminance ratios in blackboard, W107, Daylight and artificial lighting Position S1 S2 S3 S4 Sav of louvers up 7:1 3:1 3:1 down 2:1 3:1 3:1 Table F- 25: Reflection factors of materials used in Dialux

Room/material R203/W107 Brick R203 Floor R203 Noteboard R203 Wooden frame R203 Desks R203 Door R203 Lockers R203 Whiteboard W107 Blackboard W107 Desks W107 Floor

Reflection factor 34,8% 27,3% 41,6% 11,3% 48,5% 17,1% 47,1% 86,1% 13,2% 90,2% 36,4%

142

5. Appendix F Table F- 26: Results from Dialux in R203, 22 June 14:00, clear sky condition

Room number Date/time/sky Artificial light Sunshade % points meet requirement White/blackboard visible?

Smartboard visible?

R203 22 June 2012/14:00/Clear Sky Up

Light off Horizontal 50째

93,8% Yes No

75,0% 50,0% Yes No

Yes No

Down Up

Light on Horizontal 50째

0,0% 100,0% No yes

Yes No

Down

100,0% 93,8% 81,2% Yes No

Yes No

No no

Table F- 27: Results from Dialux in R203, 22 March 12:00, mixed sky condition

Room number Date/time/sky Artificial light Sunshade % points meet requirement White/blackboard visible?

Smartboard visible?

Up

R203 22 March 2012/12:00/Mixed Sky Light off Light on Dow Horizontal 50째 n Up Horizontal 50째

75,0% Yes No

62,5% Yes No

18,8% No No

0,0% 100,0% No yes

Yes No

100,0% 81,2% 62,5% Yes No

Table F- 28: Results from Dialux in R203, 22 December 09:00, overcast sky condition

Room number R203 Date/time/sky 22 December 2012/09:00/Overcast sky Artificial light Light off Light on Sunshade Up Horizontal Up Horizontal % points meet requirement 6,2% 0,0% 68,8% 68,8% White/blackboard visible?

No No No No Smartboard visible?

Yes Yes No no Table F- 29: Results from Dialux in W107, 22 June 14:00, clear sky

W107 22 June 2012/14:00/Clear Sky Artificial light Light off Sunshade Up Down % points meet requirement 100,0% 100,0% White/blackboard visible?

Yes Yes Smartboard visible?

No No

143

Down

No No

No no

5. Appendix F Table F- 30: Results from Dialux in W107, 22 March 12:00, mixed sky

W107 22 March 2012/12:00/Mixed Sky Artificial light Light off Sunshade Up Down % points meet requirement 100,0% 50,0% White/blackboard visible?

Yes No Smartboard visible?

No No Table F- 31: Results from Dialux in W107, 22 December 09:00, overcast sky condition

W107 22 December 2012/09:00/Overcast sky Artificial light Light off Light on Sunshade Up Down % points meet requirement 18,9% 100,0% White/blackboard visible?

No Yes Smartboard visible?

Yes No

144

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