GUIDELINE AND DESIGN ASSESSMENT METHODOLOGIES FOR OUTDOOR SPACES IN URBAN HOT ARID CLIMATE. by John Salama

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Term 2 Research Paper

TERM 2 RP

How to adapt Environmental and physiological parameters to achieve Thermal comfort in outdoor spaces.

GUIDELINE AND DESIGN ASSESSMENT METHODOLOGIES FOR OUTDOOR SPACES IN URBAN HOT ARID CLIMATE. John Salama AA SED MArch Sustainable Environmental Design 2015-17 Architectural Association School of Architecture - Graduate School

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Authorship Declaration Form Architectural Association School of Architecture – Graduate School

PROGRAMME: AA SED MArch Sustainable Environmental Design 2015-17

TITLE: GUIDELINE AND DESIGN ASSESSMENT METHODOLOGIES FOR OUTDOOR SPACES IN URBAN HOT ARID CLIMATE.

NUMBER OF WORDS (Excluding footnotes and references):

4169

STUDENT NAME: JOHN SALAMA.

DECLARATION: “I certify that the contents of this document are entirely my own work and that any quotation or paraphrase from the published or unpublished work of others is duly acknowledged.”

Signature:

Date: 25th April 2016

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Table of Contents:

0. Authorship declaration form………………………………………………………………………………………....03 0. Abstract……………………………………………………………………………………………………………..…....05 1. Introduction……………………………………………………………………………………………….….…………05 2. Hot Arid Region and the Climate of Cairo. 2.1 Location and Climate……………………………………………………………………………………..….……06 2.2 Conclusion…………………………………………………………………………………………………………..08 3. Outdoor Quality Assessment Methodologies. 3.1 Thermal Comfort models for outdoor urban spaces. 3.1.1 Actual Sensation Vote (ASV)……………………………………………………………………………..09 3.1.2 Predicted Mean Vote (PMV)…….……………………………………..………………………………….09 3.1.3 Predicted Percentage of Dissatisfaction (PPD)……….………………………………………………10 3.1.3 Physiological Equivalent Temperature (PET)……..….……………………………………………….10 3.2 Conclusion…………………………………………………………………………………………………………..11 4. Analytic Studies. 4.1 Potential Design Scenarios. 4.1.1 Summer Scenarios…………………………………………………………………………………………12 4.1.2 Winter Scenarios……………………………………………...……………………………………………13 4.2 Design Guideline. 4.2.1 Physiological Parameters………………………………………………………...………………………13 4.2.2 Environmental Parameters………………………………………………….……………………………14 5. Conclusion………………………………………………………………………………………………...…………….15 6. Acknowledgements……………………………………………………………………………………...…………….15 7. References………………………………………………………………………………………………………...…….15 8. Dissertation Topic Outline…………………………………………………………………………………..………..16

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Abstract: This Paper highlights methodologies for assessing Thermal comfort in hot arid climate region with a design guideline recommendations that was generated for Cairo climate for the purpose of generating a set of rules that could be followed by designers, or urban planners for better understanding of the perceptions of outdoor spaces Thermal comfort band. Also the guideline was generated as preparation for a dissertation project that will discuss the potential of using outdoor areas as spaces for exhibiting and performing. The guideline in this paper should be developed in the dissertation project through sets of fieldwork, analytical work and testing different scenarios simulation that will be generated by specific computer software.

Keywords: Urban Arid Climate, Thermal Comfort, PET, Outdoor spaces, Cairo climate, Design Guideline.

1. Introduction:

There is huge public demand on creating more outdoor spaces as it became crucial for improving the quality of life in cities. Recently studies shows that cities with more usable public outdoor areas have better percentage of satisfied people, those kind of studies evoked governments and societyâ&#x20AC;&#x2122;s reaction to invest more in public outdoor spaces than before. The possibilities of redefining the concept of some spaces that was usually used as indoor spaces to make it function in outdoor became more achievable if designers gave more attention towards such details and parameters that can be adapted to achieve better quality of outdoor spaces, However this possibilities had a big challenge that should be more considered which is the climate change, as it became hard to predict the weather in the future, therefore it became difficult for well-designed outdoor spaces to have the same performance in the future. There is no doubt that controlling outdoor spaces is not as easy as controlling indoor spaces, that is why, Recently a lot of funded studies have been done to find an easy way to help designers and urban planners assessing their designs based on the thermal comfort model, however most of those studies doesnâ&#x20AC;&#x2122;t take into consideration the physiological parameters as it is generated based on environmental parameters only.

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2. Hot Arid Region and the Climate of Cairo. 2.1 Location and Climate: Cairo is the Capital of Egypt and it is part of Greater Cairo, the city covers an area of 528 km 2. Cairo is located at a latitude of 30° 3'8.03" North and a longitude of 31°15'44.40" East at an Elevation of 139m. According to KoppenGeiger climatic classification, Cairo is characterized by Hot Arid Dessert Climate (FIG 2.1). Egypt is a transcontinental country, covers the area of 1,010,408 km2, spanning in the north east corner of Africa and south west corner of Asia. Greater Cairo is the largest metropolitan area in the Middle East and The Arab World, and 15th Largest in the World, where the famous Giza pyramid complex, and a lot of museums located.

Cairo

FIG 2.1 Showing World Climate Classification map (source: Koppen-Geiger climatic classification).

Dry Bulb Temperature: There is low variation in the monthly mean temperature in Cairo (FIG 2.2), as in summer the monthly mean temperature swing between 21 °C and 27 °C with average difference of 5 °C between April and October, while in winter the monthly mean temperature swing between 13.5 °C and 18.5 °C with average difference of 5 °C between November and March, with average yearly mean temperature of 21 °C. However the fluctuation in Daily mean temperature between day and night is not big in summer but it is significant big in winter, as in summer July, the average day and night fluctuation could vary between 46 °C and 18 °C with average of 8 °C difference of temperature in one day. And in Winter December, the average day and night fluctuation could vary between 30 °C and 3 °C with 13 °C average difference in temperature. 35 30 25 20 15 10

DECEMBER

NOVEMBER

OCTOBER

AUGUST

SEPTEMBER

Comfort band limit [°C] AVERAGE MONTHLY MAXIMUM TEMPERATURE [°C]

JULY

JUNE

MAY

APRIL

MARCH

FEBRUARY

JANUARY

AVERAGE MONTHLY MEAN TEMPERATURE [°C] AVERAGE MONTHLY MIMIMUM TEMPERATURE [°C]

FIG 2.2 showing annual mean temperature for Cairo, Weather station: Cairo Airport (source software: Meteonorm 7.00).

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Relative Humidity: Unlike most of Egyptian cities, Cairo often has quite high humidity as the average values of Relative Humidity ranges from 46% to 61% with 56% yearly average (TAB 2.1), as it is located not far from The Mediterranean Sea and The Delta, Also the River Nile is going through the middle of Greater Cairo, separating it into West Bank which is Giza governorate and East Bank which is Cairo Governorate. Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Relative humidity (%)

Year 56

TAB 2.1 showing monthly average Relative Humidity for Cairo, (source: World Meteorological Organization WMO).

Solar Radiation: The hourly sunshine in Cairo is quite high during the year, as well as the solar radiation (TAB 2.2). South facing vertical surfaces, receives the highest annual amount of solar radiation. North orientation is highly recommended as it has the least solar exposure during the summer. As there is high solar radiation especially in summer, there is a great need for solar protection for horizontal surfaces and south facing surfaces ( 2.3). Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

sunshine (hours)

213

234

269

291

324

357

363

351

311

292

248

198

Year 3,451

TAB 2.2 showing monthly average Solar Radiation for Cairo, (source: World Meteorological Organization WMO). 8 6 4 2

DECEMBER

NOVEMBER

OCTOBER

SEPTEMBER

AUGUST

JULY

JUNE

MAY

APRIL

MARCH

FEBRUARY

JANUARY

AVERAGE DAILY DIFFUSE HORIZONTAL SOLAR RADIATION [kWh/m²] AVERAGE DAILY DIRECT HORIZONTAL SOLAR RADIATION [kWh/m²]

FIG 2.3 showing monthly average Solar Radiation for Cairo, Weather station: Cairo Airport (source software: Meteonorm 7.00)

Air Velocity and Wind Orientation: The annual prevailing wind is mostly from North-West, However there is slight change in wind direction during winter (FIG 2.5). Average monthly wind velocity doesn’t exceed 4.5 m/s (FIG 2.4). However, wind storm could happen twice a year or less, bringing Western desert dust into the city. There is also a wind incident locally known as “khamaseen”, it is a dry sandy local wind blowing from the south. Usually it happens in April, but occasionally occur between March and May, it lasts for several hours, carries great quantities of sand and dust from the desert with a speed up to 140 km/h and the humidity usually drops below 5%

DECEMBER

NOVEMBER

OCTOBER

SEPTEMBER

AUGUST

JULY

JUNE

MAY

APRIL

MARCH

FEBRUARY

JANUARY

5 4 3 2 1 0

AVERAGE WIND SPEED [m/s]

FIG 2.4 showing annual wind velocity for Cairo, Weather station: Cairo Airport (source software: Meteonorm 7.00).

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FIG 2.5 showing wind rose study for Cairo, Weather station: Cairo Airport (source software: Ladybug).

Precipitation: Chances of Rainfall in Cairo is rare, it only happens in colder months as the precipitation amount is really low during the year (TAB 2.3). Snowfalls are extremely rare, however small amount of snow fell on Cairoâ&#x20AC;&#x2122;s Eastern suburb in 13 December 2013 the first time Cairo receives this kind of precipitation in many decades. Also in December 2015, Part of Cairo were covered with snow due to the massive decrease in dry bulb air temperature. Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

precipitation mm

3.8

1.1

0.5

0.1

0.7

3.8

5.9

Year 24.7

TAB 2.3 showing monthly average Precipitation for Cairo, (source: World Meteorological Organization WMO).

2.2 Conclusion: To conclude that, Cairoâ&#x20AC;&#x2122;s climate is achieving the comfort band on nearly six months from May to October, mostly in the summer period, as it is in the comfort band most of the night, but the high solar radiation during the day is affecting the human comfort. Also it is not far from the comfort band during winter, few strategies could easily help achieve human comfort for outdoor spaces such as the amount of cloth that person can wear and level of human activities. Humidity percentage in Cairo is an advantage for the weather during summer time, as it help achieve less dry weather which could be a reason for why most of the summer is achieving the comfort band, however the winter is not achieving the comfort band due to the increasing percentage of relative humidity. Some natural incidents had occur recently in Cairo such as snow and higher level of precipitation could be a great witness of the Global Warming, as the winter is getting cooler every year and summer is getting warmer. Taking into consideration the future climate became crucial in the design stage of any project especially when it comes to outdoor spaces, as it is harder to control the microclimate than indoor spaces. Also considering the extreme conditions that occur once or twice a year such as sand storms is very important, as this conditions are hard to be expected as it occur in different seasons during the year and the amount of it is changing.

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3. Outdoor Quality Assessment Methodologies. Recently, there has been big demand from different private and governmental sectors to assess the quality of outdoor spaces and the level of human comfort especially for the microclimate of urban areas. A lot of funded researches and experiments have been developed in this topic in order to find an accurate way for assessing the quality of outdoor spaces. This part of this paper will point out some methods and criteria for measuring the quality of microclimate outdoor spaces, some of those methods are based on field work while other methods could be done through applying old findings and use of weather database for the needed location and use it as input for computer software to generate assessment results. Also it will discuss the difference between those methods and how to choose between one of those methods depend on the needs to get the most accurate results. Some of those methods are part of RUROS (Rediscovering Urban Realm of open spaces) project and other projects that was done by academic organizations.

3.1 Thermal Comfort models for outdoor urban spaces: According to RUROS project, most of Thermal comfort studies are based on purely physiological model as a major parameter to calculate thermal satisfaction, However, Field surveys have proved that using only physiological model is inadequate to predict an accurate results for outdoor thermal comfort. Major Environmental parameters should be taken into consideration, In order to assess the outdoor thermal comfort for outdoor spaces such as Air Temperature, Relative Humidity, Air Velocity and Mean Radiant Temperature, while some physiological parameters should also be considered as well, such as Level of cloth insulation (clo) and level of human activity and metabolic rate (met).

3.1.1 Actual Sensation Vote (ASV): This model of Thermal Assessment was developed by RUROS project. The project was funded by the EU, it provided by set of field surveys carried out across Europe, which included extensive microclimate monitoring and modeling of open spaces with different typologies. The Thermal Sensation model was developed to be used by Architects, Planners or Urban Designers at early stage of the design process, in order to evaluate the performance of different design proposals. Actual sensation Vote has been evaluated on scale of 5 points ranges from cold to warm as shown in (TAB 3.1). This method of Assessment is based on a questionnaire that need to be done by field survey, The advantage of this method is that it doesn’t depend only on the physiological factor as it deals with actual humans that describe their feeling, and that could be different from culture to other depend on the physiological factor, as human thermal comfort could be changes based on the habits, Gender or age. In order to develop this methodology, a formula was generated based on comparing this method with other well tested methods as Predicted mean vote (PMV) method, using variables: air temperature (Tair,°C), the difference of Tglobe – Tair(Tga, °C) as a proxy for sunlight [6], wind speed (V, m/s) and relative humidity (RH,%). ASV = 0.061 Tair + 0.091 Tga -0.324 V + 0.003 RH -1.455.

cold

Slightly Cold

Neutral

Slightly Warm

Warm

TAB 3.1 showing scale of Actual Sensation Vote (ASV).

3.1.2 Predicted Mean Vote (PMV): This method was originally developed for indoor environment and gradually employed for the outdoor environment as well by Povel Ole Fanger and later adopted as ISO standard to describe Thermal comfort, it is a Thermal sensation scale that range from cold with value of (-3) to Hot with value of (3) as shown in (TAB 3.2). The PMV model was built on ASHRAE 1992, ISO 1994 standards, Based on data that was collected by subjecting large number of people to different climate conditions and having them to select on the scale the best situation that described their comfort sensation. After collecting the results, a mathematical equation for the relationship between

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all the physiological and environmental factors considered was generated. The recommended acceptable PMV range for thermal comfort according to ASHRAE 55 is between -0.5 and +0.5. There is a comparison done by RUROS between the Actual Sensation Vote (ASV) method and the Predicted Mean Vote (PMV) Method, This comparison was done by getting the questionnaire results for the ASV model and compare it with the results from the mathematical equation of the PMV shown in (FIG 3.1), This comparison was done in Athens to show the difference between the two methods. Predicted Mean Vote sensation scale Value Sensation -3 -2 -1 0 1 2 3

Cold Cool Slightly cool Neutral Slightly warm Warm Hot

TAB 3.2 showing value scale for predicted mean vote (PMV).

FIG 3.1 Showing comparison between ASV and PMV (Reference: RUROS Project).

3.1.3 Predicted Percentage of Dissatisfaction (PPD): This method with developed by Povel Ole Fanger with the Predictive Mean Vote (PMV) method to predict the percentage of users that is not satisfied with the thermal conditions of the space, it is function of PMV, as the PPD increases when the PMV go near the Neutral level on the scale. The Maximum value of PPD is 100%, and as it is hard to satisfy all the users at the same time, the recommended acceptable value for the PPD according to ASHRAE 55 is less than 10% dissatisfied users. The math equation behind the two methods of PMV and PPD applies only to users exposed for a long period to constant conditions at a constant metabolic rate. As PPD id function of PMV, Frangerâ&#x20AC;&#x2122;s thermal comfort model defined the relationship between PMV and PPD in the following equation: [-90.3353PMV4+0.2179PMV2)] PPD = 100 - 95 e

3.1.4 Physiological Equivalent Temperature (PET): The Physiological Equivalent Temperature (PET) is a method that was developed by Peter Hoppe in 1999 in order to find more accurate way to assess thermal comfort for outdoor spaces. It was developed as a thermal index to evaluate the thermal conditions of the environment based on the physiological aspects of human body. The method of assessment on based on natural environmental parameters as Air temperature, Radiant temperature, Air velocity and air humidity. Shown in (Tab 3.3) Ranges of the physiological equivalent temperature (PET) for different grades of thermal perception by human beings and physiological stress on human beings; internal heat production: 80 W, heat transfer resistance of the clothing: 0.9 clo (According to Matzarakis and Mayer 1996). However the problem of the PET model is that it doesnâ&#x20AC;&#x2122;t take into consideration the change of cloth level (CLO) or the human activity level change as it consider it as a fixed values with clothing of 0.9 CLO and internal heat production of 80 W, That is why the model was developed to another method (mPET) that takes into consideration those values.

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PET 4°C 8°C 13°C 18°C 23°C 29°C 35°C 41°C Over 41°C

Thermal perception Very cold Cold Cool Slightly cool Comfortable Slightly warm Warm Hot Very hot

Grade of physiological stress Extreme cold stress Strong cold stress Moderate cold stress Slight cold stress No thermal stress Slight heat stress Moderate heat stress Strong heat stress Extreme heat stress

Tab 3.3 Showing Scale of PET and grades of physiological stress (Source: Matzarakis and Mayer 1996).

3.2 Conclusion: There are a lot of methods that was developed to assess the thermal comfort of the outdoor spaces, however the four mentioned methods are more recommended to use as it takes into consideration more aspects such as psychological and physiological aspects. The data shown in ( Tab 3.4) could help find the suitable method to use in each design stage, it also shows the advantage and disadvantages of the four different methods, it also shows the recommended results based on standards to achieve the thermal comfort for outdoor spaces.

Methodology Comparison Method Actual Sensation Vote (ASV).

When to use  

Early Design Stage. Based on Field survey.

Why to use 



Predicted Mean Vote (PMV).

 

Assessment of existing design. Based on Mathematical Formula.



Predicted Percentage of Dissatisfaction (PPD)

 

Physiological Equivalent Temperature (PET)

 

Assessment of existing design. Based on Mathematical Formula.



Assessment of existing design. Based on Mathematical Formula.



Tab 3.4 Showing comparison between different outdoor assessment methods.



To evaluate the outdoor comfort based on human psychological perceptions. To compare sensation difference between different cultures.

To get more developed results that takes into consideration the physiological aspects. Recommended to be between -0.5 and +0.5 according to ASHRAE 55.

To know the percentage of dissatisfied users in the space. Recommended less than 10% according to ASHRAE 55. To help find the assessment result if it is located in comfort zone or not Can use mpet to have variables in clo and met values

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4. Analytic studies: In order to better understand the design needs for outdoor spaces in Cairo, some analytic work using mPET method was done in average summer day and average winter day, the scenarios mPet results helps to make brief design strategies for different days during the year by modifying some parameter to adapt the thermal comfort.

4.1 Potential Design Scenarios: The scenarios was generated by using Rayman Pro on average 35 years old male, with Height of 175 cm and weight of 75kg. All the weather data were generated by Meteonorm using Cairo Airport Weather station. Used Physiological Variables: Clothing level: Trousers, short-sleeved shirt = 0.57 CLO. Insulated coveralls, long-sleeved thermal underwear, long underwear bottoms = 1.37 CLO. Activity level: Seated relaxed = 104 W. Standing, medium activity (shop assistant, domestic work) = 209 W. Walking or running on the level, 5 km/h = 360 W.

4.1.1 Cairo Average September Summer Scenarios The following scenario shown in (Tab 4.1) for average September summer day was generated by fixing all the micro climate parameters that was taken from the database and start showing the difference of mPet results when only change the level of activity parameters, as three average daily activities were chosen to be the variable when the user will be in relaxed posture, standing (medium activity), or running at speed of 5 km/h. According to the yearly analysis shown in (FIG 2.2), the comfort band in Summer September in Cairo is located in the range of 25 째C to 31째C, on average summer day as shown in (Tab 4.1), this could easily be achieved in outdoor spaces in Cairo during the day if the user is having a relaxed posture, but that will change if the user start to have more active posture. However at the night, because of the big fluctuation of the air temperature, the comfort band level of activity starts to change as it demand more active posture than being sitting or relaxed.

Time (Hour)

Condition

Air Temperature (째C)

Relative Humidity (RH)

Wind Velocity (m/s)

Activity Level (W)

Clothing Level (CLO)

mPET (째C)