Group Report: Building Analysis_Part 1 by Jong Hee Paik

UNIVERSITY OF NOTTINGHAM DEPARTMENT OF ARCHITECTRURE AND BUILD ENVIRONMENT

Building Analysis 1 (K13BA1)

GROUP G: 

Dainius Alonderis

[4122017]



Valentas Rutkauskas

[4119827]



Kyriakos Orfanos

[4114038]



Xiaofang Xu

[4158955]



Jong Hee Paik

[4158998]

15 January 2013

Table of Contents Table of Contents ................................................................................................................................ i List of figures ......................................................................................................................................iii List of tables ........................................................................................................................................v STAGE 1 .............................................................................................................................................. 1 1.1 Design Approach ...................................................................................................................... 1 1.2 Building Description ................................................................................................................. 2 1.2.1 Floor Plans ......................................................................................................................... 4 1.3 Design Conditions ..................................................................................................................... 7 1.3.1 External Conditions ........................................................................................................... 7 1.3.1.1 Microclimate Investigation ........................................................................................ 7 1.3.1.2 Temperature .............................................................................................................. 7 1.3.1.3. Wind .......................................................................................................................... 9 1.3.1.4 Solar Radiation ......................................................................................................... 11 1.3.1.5 Relative Humidity ..................................................................................................... 12 1.3.2 Internal Conditions .......................................................................................................... 13 1.3.1.1 Comfort Standards ................................................................................................... 13 STAGE 2 ............................................................................................................................................ 17 2 Thermal Performance ............................................................................................................... 17 2.1 Manual Calculations ........................................................................................................... 17 2.1.1 Internal Heat Gains...................................................................................................... 17 2.1.2 Solar Heat Gains .......................................................................................................... 19 2.1.3 Fabric Heat Gains ........................................................................................................ 25 2.1.4 Ventilation Heat Gains ................................................................................................ 25 2.2 Comparison between Ecotect and Manual Calculation Results ........................................ 26 2.3 Thermal Performance Investigation Using Ecotect ............................................................ 28 2.3.1 Model .......................................................................................................................... 28 2.3.2 Zone Settings ............................................................................................................... 29 2.4 Optimization of Design Variables ....................................................................................... 30 2.4.1 Shading ........................................................................................................................ 31 2.4.2 Windows...................................................................................................................... 33 2.4.3 Thermal Evaluation of Windows ................................................................................. 35 2.4.4 Retrofit of Building Envelope and Internal Surfaces ................................................... 36 i

2.4.5 Selection of Thermal Insulation Material for Retrofit ................................................. 37 2.4.6 Walls ............................................................................................................................ 38 2.4.7 Wall Elements.............................................................................................................. 39 2.4.8 Floors and Ceilings....................................................................................................... 42 2.4.9 Floor and Ceiling Elements .......................................................................................... 43 2.4.10 Roof ........................................................................................................................... 45 2.4.11 Roof Structure Cases ................................................................................................. 45 2.4.12 Internal Heat Gains.................................................................................................... 48 2.5 Comparison between Base Case and Improved Model ..................................................... 50 2.6 Ventilation .............................................................................................................................. 51 2.6.1 Natural Ventilation .......................................................................................................... 52 2.7 Daylight Investigation for Base Case ...................................................................................... 52 2.8 Renewables ............................................................................................................................ 56 2.8.1 Sources with Limited Potential ....................................................................................... 57 2.8.2 Integration of Renewables In The Built Environment ..................................................... 58 STAGE 3 ............................................................................................................................................ 63 3.1 Thermal Performance ............................................................................................................ 63 3.2 Ventilation .............................................................................................................................. 65 3.3 Daylight .................................................................................................................................. 65 3.3.1 Further Lighting Improvements ...................................................................................... 67 3.4 Renewables ............................................................................................................................ 68 STAGE 4 ............................................................................................................................................ 69 4.1 Air Conditioning System ......................................................................................................... 69 4.2 Realistic Summaries of the Potential Roles of Renewable Energy ......................................... 69 References ........................................................................................................................................ 71 Appendices .......................................................................................................................................... I

List of figures Figure 1 Site plan of the building ....................................................................................................... 3 Figure 3 Ground floor plan ................................................................................................................. 4 Figure 4 First floor plan ...................................................................................................................... 5 Figure 5 Second floor plan ................................................................................................................. 6 Figure 6 Hottest day (average) ........................................................................................................... 7 Figure 7 Hottest day (peak) ................................................................................................................ 8 Figure 8 Coldest day (average) ........................................................................................................... 8 Figure 9 Coldest day (peak) ................................................................................................................ 9 Figure 10 Annual prevailing winds in Singapore .............................................................................. 10 Figure 11 Monthly prevailing winds in Singapore ............................................................................ 10 Figure 12 Stereographic Diagram of Singapore (Ecotect weather tool) .......................................... 11 Figure 13 Insolation map of the world ............................................................................................. 12 Figure 14 Psychrometric chart - hourly data points by month ........................................................ 16 Figure 15 Psychrometric chart - monthly mean minimum/maximum ............................................ 16 Figure 16 Initial shading device and shading on April 22nd 3pm ...................................................... 20 Figure 17 Solar irradiation on April 22nd........................................................................................... 22 Figure 18 West side shading of the building on December 31st 1pm .............................................. 23 Figure 19 Base case building 1 ......................................................................................................... 28 Figure 20 Base case building 2 ......................................................................................................... 29 Figure 21 Shading - case 1 ................................................................................................................ 32 Figure 22 Shading - case 2 ................................................................................................................ 32 Figure 23 Shading - case 3 ................................................................................................................ 32 Figure 24 Shading case - 4 ................................................................................................................ 33 Figure 25 Direct solar gains dependency on shading device ........................................................... 33 Figure 26 Direct solar and fabric heat gains dependency on windows ........................................... 36 Figure 27 Case 1 wall - structure ...................................................................................................... 39 Figure 28 Case 2 - wall structure ...................................................................................................... 40 Figure 29 Case 3 - wall structure ...................................................................................................... 41 Figure 30 Fabric and indirect solar heat gain dependency on wall.................................................. 42 Figure 31 Ground floor structure ..................................................................................................... 43 Figure 32 Internal floor structure ..................................................................................................... 44 Figure 33 Case 1 - roof structure ...................................................................................................... 45 Figure 34 Case 2 - roof structure ...................................................................................................... 46 Figure 35 Fabric and indirect solar heat gains dependency on roof along with cavity and aerogel wall ................................................................................................................................................... 47 Figure 36 Internal heat gains distribution by source ....................................................................... 49 Figure 37 Improved internal heat gains distribution by source ....................................................... 50 Figure 38 Monthly heat gains, base case and improved model ...................................................... 50 Figure 39 Daylight levels for ground floor ........................................................................................ 53 Figure 40 Daylight levels for 1st floor ............................................................................................... 53 Figure 41 Daylight levels for 2nd floor............................................................................................... 54 Figure 42 Ground floor area needing surplus lighting ..................................................................... 55 Figure 43 1st floor area needing surplus lighting .............................................................................. 55 Figure 44 2nd floor area needing surplus lighting ............................................................................. 56 iii

Figure 45 Singapore's geothermal gradient ..................................................................................... 57 Figure 46 Photovoltaics modules ..................................................................................................... 59 Figure 47 Options for BIPV installations........................................................................................... 60 Figure 48 Heat gains breakdown - base case ................................................................................... 63 Figure 49 Heat gains breakdown – cavity wall ................................................................................. 63 Figure 50 Heat gains breakdown aerogel wall ................................................................................. 64 Figure 51 Daylight levels for ground floor (improved) ..................................................................... 66 Figure 52 Daylight levels for 1st floor (improved) ........................................................................... 66 Figure 53 Daylight levels for 2nd floor (improved) .......................................................................... 67 Figure 54 Light tube ......................................................................................................................... 68

List of tables Table 1 Singapore wind weather statistics....................................................................................... 11 Table 2 Monthly average daily solar insolation in Singapore .......................................................... 12 Table 3 Singapore relative humidity (National environment agency of Singapore) ........................ 13 Table 4 Acceptable environmental conditions in summer by CIBSE Guide A, 2006 ........................ 14 Table 5 Acceptable internal design conditions and heat gains in Singapore ................................... 15 Table 6 Internal heat gains ............................................................................................................... 19 Table 7 Window dimensions ............................................................................................................ 19 Table 8 Shaded and non-shaded area of west sided facade ............................................................ 21 Table 9 Calculation of solar heat gains on April 22nd ...................................................................... 21 Table 10 Solar heat gains on April 22nd ........................................................................................... 21 Table 11 shaded and non-shaded area for west side ...................................................................... 24 Table 12 Calculation of solar heat gains on December 31st ............................................................ 24 Table 13 Solar heat gains on December 31st .................................................................................... 24 Table 14 Fabric heat gains ................................................................................................................ 25 Table 15 Mass flow rate ................................................................................................................... 26 Table 16 Enthalpies in inside and outside ........................................................................................ 26 Table 17 Total ventilation heat gains ............................................................................................... 26 Table 18 Comparison between Ecotect and manual calculation results ......................................... 26 Table 19 Example of annual load table with monthly averages ...................................................... 31 Table 20 Direct solar gain dependency on shading device .............................................................. 33 Table 21 Direct solar and fabric heat gains dependency on windows ............................................. 36 Table 22 Case 1 wall - elements ...................................................................................................... 39 Table 23 Case 1 wall - key features .................................................................................................. 39 Table 24 Case 2 - wall elements ....................................................................................................... 40 Table 25 Case 2 - wall key features .................................................................................................. 40 Table 26 Case 3 - wall elements ....................................................................................................... 41 Table 27 Case 3 - wall key features .................................................................................................. 41 Table 28 Fabric and indirect solar heat gains dependency on wall ................................................. 42 Table 29 Ground floor elements ...................................................................................................... 43 Table 30 Ground floor key features ................................................................................................. 43 Table 31 Internal floor elements ...................................................................................................... 44 Table 32 Internal floor key features ................................................................................................. 44 Table 33 Floor and ceiling reflectances ............................................................................................ 45 Table 34 Case 1 - roof elements ....................................................................................................... 46 Table 35 Case 1 - roof key features .................................................................................................. 46 Table 36 Case 2 - roof elements ....................................................................................................... 46 Table 37 Case 2 - roof key features .................................................................................................. 47 Table 38 Fabric and indirect solar heat gains dependency on roof along with cavity and aerogel wall ................................................................................................................................................... 47 Table 39 Max cooling load, total heat gains and monthly heat gains for base case and improved models .............................................................................................................................................. 51 Table 40 Fresh air requirements for each floor ............................................................................... 51 Table 41 Some of the most efficient available PV panels ................................................................ 61

STAGE 1 1.1 Design Approach The excess use of fossil fuels has led to an increased amount of CO2 concentration in the atmosphere, which has had a major impact on the climate and the natural environment. A very large portion of these fossil fuels is being used in the built environment. The use of sustainable energy sources and energy efficient technologies in the building design can reduce the CO2 emissions significantly. This project gives us the opportunity to investigate the refurbishment of a commercial building in Singapore. This is a particularly challenging project due to the hot and humid climate. The aim is to provide the engineering design that will minimise or even eliminate CO2 emissions while keeping comfort levels high. The refurbishment design of the building is to minimize the energy demand while using renewable and efficient technologies to supplement all or most of the energy needs. Moreover, the feasibility of using passive means of controlling the environment in the building will be considered carefully. Comfort is a major priority in the design considerations. In order for occupants to feel comfortable and be productive, the temperature and humidity must be maintained at a desired level, according to the comfort standards specified for the climate of Singapore. The use of natural daylight has been proved to increase productivity in comparison to artificial lighting, so daylight will be utilised for illumination where possible. Energy efficiency is crucial for the design of a low emissions building, so all the aspects of energy demand will be considered. These include air conditioning, illumination/electricity, hot water and ventilation. Energy efficient technologies will be applied carefully for each aspect so as not to compromise comfort or each other’s performance. Before deciding on any retrofits in the building the design conditions need to be specified. These include the microclimate of the site and suitable indoor conditions for thermal comfort, ventilation and lighting. After these conditions are specified, the heat losses will be calculated along with the required ventilation rates as well as the overall electricity 1

consumption. Then the most suitable solutions and materials will be chosen for optimum energy efficiency. The heat losses will be measured again, and the option of supplementing these losses along with other energy needs (electricity, ventilation) is examined by renewable energy potential. The energy source that is most available in site should be chosen. So the retrofitting of the building in Singapore is a challenging project which requires consideration of efficient and sustainable technologies in order to minimise energy use and maximize comfort levels in the building. 1.2 Building Description The building is located in Singapore. It is a three storey building which has a rectangular shape with dimensions 10.4m height, 18.6m width and 54.4m length. The site plan of the building shows that it is surrounded by other buildings from the north, south and east sides with the first two being much closer (Figure 1). The ground floor is used as an exhibition centre, the first floor as a library and the second floor for offices. The basic spatial requirements for this building include reception areas, toilets and circulation spaces. The office floor includes an office space, a small kitchen area and a photocopy/printing room. The library includes reading rooms, book storage spaces and café. The population density values according to CIBSE guide are 10m2/person for offices and libraries, and 3m2/person for exhibition halls. These values are not expected to be constant for the exhibition centre and library. There are also several aspects affecting the thermal performance of this building, including glazing, wall and roof fabric, and ventilation which can be modified. Population also affects the thermal performance but obviously cannot be changed.

Figure 1 Site plan of the building

1.2.1 Floor Plans Updated floor plans are overlaid on old floor plans to represent uses of areas in each zone. Toilet was left as it was in the initial design outside main building envelope.

Ground Floor. Ground floor (Figure 3) is used as exhibition centre. Chilled water pump room was left unchanged and could be used as plant room. Reception remained in the same area as was before, while the rest area was split into three exhibition zones. This dividing into three exhibition halls allows better management of the space e.g. for bigger exhibitions all three halls could be used and split by subject or theme, while for smaller exhibitions only one zone could be used (no need to cool or lit other halls, hence smaller energy consumption). E1- exhibition hall 1, 2E- exhibition hall 2, E3 exhibition hall 3, R - reception, PR plant room

Figure 2 Ground floor plan

First Floor First floor (Figure 4) is used as a library and it includes book storage area, reading rooms and café.

Figure 3 First floor plan

Second Floor Second floor (Figure 5) is used for an office and it includes kitchen, printing room, cellular and open plan office. Printing room, cellular offices and the kitchen are separated while the rest is an open plan office. K - kitchen, PR printing room, CO - cellular offices

Figure 4 Second floor plan

1.3 Design Conditions 1.3.1 External Conditions 1.3.1.1 Microclimate Investigation Singapore has tropical rainforest climate with no distinct seasons. From November to January is the monsoon season, which gives its place abundant rainfall. The average rainfall is approximately 200mm a month. 1.3.1.2 Temperature The temperatures between hottest and coldest average days in Singapore is in a range between 25 and 33 °C, as can be seen from Figure 5 and 7. Temperature does not rise above 34 °C (Figure 6) on the highest peak days, that is almost the same as on average day and temperature can drop down to 20°C (Figure 8) on the coldest day peak, for a short period of time. There are no significant temperature variations during a day; usually it is as hot at night as it is during a day. In general, temperature remains more or less the same throughout a year in Singapore.

Figure 5 Hottest day (average)

Figure 6 Hottest day (peak)

Figure 7 Coldest day (average)

Figure 8 Coldest day (peak)

1.3.1.3. Wind Wind rose diagrams from Ecotect weather tool were used to investigate the wind in Singapore. They provide information about wind’s direction, speed and frequency. Figure 9 illustrates the all year prevailing wind data; the direction of the wind seems to be from north, north east side. However, after investigating wind roses individually for each month of the year (Figure 10), it has been noticed that prevailing wind direction changes according to the different month. The wind blows from similar directions around winter time, and scattered in all directions around summer. For more accurate information, we searched for more apparent data. Table 1 indicates the mean wind direction and daily wind speeds in each month. This tells that similar wind direction, N/NE takes place for winter time, S/SE for summer time, and variable wind directions in spring and autumn times. Moreover, there is no significant windy season and wind speed remains relatively small – at around 1.75m/s.

Pre vailing W inds W ind Fre que ncy (H rs)

345°

Location: SINGAPORE, SGP (1.4°, 104.0°) Date: 1st January - 31st December Time: 00:00 - 24:00 © Weather Tool

NORTH 50 km/ h

hrs

15°

381+ 330°

30°

342 304

40 km/ h 315°

266

45°

228 190

30 km/ h

152 300°

60°

114 76

20 km/ h

<38 285°

75° 10 km/ h

WEST

EAST

255°

105°

240°

120°

225°

135°

210°

150° 195°

165° SOUTH

Figure 9 Annual prevailing winds in Singapore

Prevailing Winds W ind Frequency (Hrs)

Figure 10 Monthly prevailing winds in Singapore

Table 1 Singapore wind weather statistics

1.3.1.4 Solar Radiation Because Singapore is located near the equator, the sun is high up in the sky during daytime as it can be seen from stereographic diagram in Figure 11. This results in relatively high solar radiation as can be seen from world solar insolation map (Figure 12). Table 2 shows the average daily solar insolation for each month. The insolation varies between 3.8 to 5.13 kWh/m2/day and it adds up to the total solar insolation of 1627 kWh/m2/year. Stereographic Diagram

Location: SINGAPORE, SGP Sun Position: 80.7°, 72.8° HSA: -83.3°, VSA: 87.9° © Weather Tool

345°

15°

330°

30° 10°

315°

45° 20°

30° 300°

60° 40° 1st Jul

50°

1st Jun

1st Aug 75°

60°

285° 1st May

70° 1st Sep 80° 1st Apr 270°

90° 1st Oct

1st Mar

255° 1st Feb

1st Nov 105°

10 9

18 1st Jan

1st Dec

240°

120°

225°

135°

210° Time: 12:00 Date: 1st April Dotted lines: July-December.

150° 195°

165° 180°

Figure 11 Stereographic Diagram of Singapore (Ecotect weather tool)

Figure 12 Insolation map of the world

Table 2 Monthly average daily solar insolation in Singapore

1.3.1.5 Relative Humidity One of the known characteristics of the tropical climate is the high humidity. The humidity in Singapore ranges between 60% and up to 97%. As it can be seen from the Table 3, the minimum and maximum relative humidity levels are almost the same throughout the year, and the average RH is around 84%. It can also be seen that the winter period is a little bit more humid compared to the summer period, probably due to the monsoon season.

Table 3 Singapore relative humidity (National environment agency of Singapore)

1.3.2 Internal Conditions 1.3.1.1 Comfort Standards Internal conditions of a building like lighting, temperature, humidity, and air quality affect productivity, comfort and health of the occupants, and most energy in every building is used to ensure sufficient environmental conditions for the occupants. Thus, the building services need to be optimized to make optimal use of energy to ensure adequate conditions for the occupants in the building. United Kingdom has many regulations and standards of building services designing which consider the environment. CIBSE Guide A, 2006 is the essential guidance for environmental design for buildings in the United Kingdom. Table 4 shows the acceptable environmental conditions for summer in the UK. Zone

Temperature (°C)

Ventilation Rate

Lighting Level (lux)

Office

22-24

10 l/s/p

300-500

Exhibition Hall

21-23

10 l/s/p

300

Café (bars/lounge)

22-24

10 l/s/p

100-200

Reading Room

24-25

10 l/s/p

500

Book Storage Space

21-23

10 l/s/p

200

21-23

> 5ach

200

(library lending desk) Toilets

Table 4 Acceptable environmental conditions in summer by CIBSE Guide A, 2006

Unlike the weather in UK, Singapore does not have seasonal variation. Hence, the guidance from CIBSE Guide A served as a reference for tor the building in Singapore; the comfortable temperature, required ventilation rates and lighting levels.

People living in Singapore acclimatize with the outdoor conditions and can be comfortable in higher temperatures compared to a person who lives in the United Kingdom. That allows us to have higher indoor design conditions than the ones given in CIBSE Guide. A number of ways was used to investigate comfortable temperature inside a building in Singapore:

●

Ecotect’s weather tool was used to find comfort zones using natural or mechanical ventilation, shown in Figure 13. Afterwards investigation of past work of

●

Building Research Establishment (BRE) work suggested that summer-time peak design temperatures in a ‘formal’ office should be 23±3°C, and that in an ‘informal’ office could be as high as 25±3°C(General Information, Report 31, Avoiding or minimizing the use of, air-conditioning–A research report from the EnREI Programme).

●

Adaptive model described in CIBSE Guide A, 2006.

Having familiarized with these three sources, we came up with table 5 showing thermal conditions in the building that would be comfortable for occupants, while environmental conditions like ventilation and lighting level remained the same as for United Kingdom. The density of occupation is also included, with assuming that the density of occupation in exhibition hall is the same as in meeting/conference room or bar/restaurant. The heat gains from people can be considered to be the same in all zones, 80W of sensible heat gains has been assumed.

Zone

Temperature (°C)

Ventilation Rate

Lighting Level

Density 2

(m /person)

(lux)

Equipment Sensible Latent and lighting heat gain heat gain heat gain

from

(W/m2)

people

(W/m ) (W/m2) Office

24-26

10 l/s/p

400

Exhibition Hall

23-25

10 l/s/p

300

Café

24-26

10 l/s/p

150

Reading Room 26-27

10 l/s/p

500

Book Storage

23-25

10 l/s/p

200

26-28

> 5ach

200

(bars/lounge)

Space (library lending desk) Toilets

Table 5 Acceptable internal design conditions and heat gains in Singapore

In addition to above criteria, the level of relative humidity also play an important role in human comfort. Humans are sensitive to humidity of the air because the human body uses evaporative cooling as the primary mechanism to regulate temperature. According to the CIBSE Guide A, the acceptable RH level that an occupant feels comfort ranges from 50%-70%. On the other hand, since Singapore has relatively high average temperatures and humidity, and as mentioned earlier, the people acclimatize with their environment, thus the bearable RH levels can be assumed to be higher than the UK’s. This also means that their minimum acceptable RH level may also be higher; the people in Singapore may not feel comfort with RH value of 50%, unlike the people in the UK in the same given temperature.

The RH levels are correlated with the temperatures. For instance, under a condition of the same given temperature 25°C, RH level of 100% will make the person feel like it is 28°C, and RH level of 30% will make it feel like it is 22°C; too high or too low will both cause discomfort. This is because under humid conditions, the rate at which perspiration 15

evaporates on the skin is lower, thus we feel warmer compared to when the RH level is low. Figures 13 to 14 show Ecotect’s weather tool analysis. A red box indicates the Adaptive comfort levels in conditions of natural ventilation; a person can feel comfort up to RH level of 90% in naturally ventilated building in Singapore.

Psychrome tric Chart Location: SINGAPORE, SGP Data Points: 1st January to 31st December Weekday Times: 00:00-24:00 Hrs Weekend Times: 00:00-24:00 Hrs Barometric Pressure: 101.36 kPa © Weather Tool

COMFORT: Natural Ventilation 30

25 January February March April May June July August September October November December

5 Comfort

DBT(°C)

Figure 13 Psychrometric chart - hourly data points by month

Psychrome tric Chart Location: SINGAPORE, SGP Display: Monthly Mean Minimum/ Maximum Barometric Pressure: 101.36 kPa © Weather Tool

COMFORT: Natural Ventilation

A M N OM J J SAF

NFMJ DS AOA J

5 Comfort

DBT(°C)

Figure 14 Psychrometric chart - monthly mean minimum/maximum

STAGE 2 2 Thermal Performance This section focuses on the energy evaluation of the building. As the main features of the building have been identified it was necessary to carry out thermal evaluation. Generally, several cases of the building design have been investigated in order to obtain comparable results. The first case evaluated was so called base case scenario, where all the materials and shading devices were kept unchanged. However, to improve the building performance the various design stages were suggested so that an overall result has shown that the thermal performance of the building has been increased substantially. In addition, before relying on Ecotect it was necessary to do manual calculations to compare the results. The calculations have been performed for internal, solar, fabric and ventilation heat gains. Thus, if the reliability of Ecotect was evaluated properly, the further building simulations could be done. 2.1 Manual Calculations In order to check that the model used in Ecotect is correct, we performed a number of rough manual calculations to investigate the heat gains. 2.1.1 Internal Heat Gains

The sensible and latent heat gain assumptions are made in STAGE 1 and shown in the Table 5. The main formulae to be used in the manual calculations are represented below. 1. People sensible heat gain ̅ Where: 

- sensible heat gain from people 17



̅ - people sensible heat gain per area



A - the area of each floor, which is 972

2. Equipment & lighting heat gain ̅̅̅ Where: 

- the equipment and lighting heat gain



̅̅̅ - equipment and lighting heat gain per area



A - the area of each floor, which is 972

3. People latent heat gain ̅ Where: 

- latent heat gain from people



̅ - people latent heat gain per area



A - the area of each floor, which is 972

The results of the internal heat gain in each floor and sources are represented in the Table 6. The sum of the internal heat gains has been obtained to be at 141kW.

People ( Exhibition

)

Equipment

Sensible

Latent

Internal

& Lighting

Heat gain

heat

heat gain

(

( )

(

( )

)

50544

19440

69984

Library

22356

5832

28188

Office

36936

5832

42768

Total

109836

centre

31104 18

140940

Table 6 Internal heat gains

2.1.2 Solar Heat Gains The building has only two facades on the east and west sides, thus there are no direct solar gains considered for north and south walls. Moreover, it has been found from Ecotect that the east façade is fully shaded while the west is not. Therefore, the manual calculations have been carried out appropriately and most of work has been done for the east side of building. The Table 7 shows the dimension of the windows. The L (length) is the total length of the windows on either building floor. West side

East side

H (m) L (m) A (

) H (m) L (m) A (

Exhibition centre 2.1

35.5

72.9

2.23

19.3

43.7

Library

2.1

35.5

72.9

2.3

22.3

50.5

Office

2.1

35.5

72.9

2.3

9.0

20.4

Total area, m2

218.7

)

114.7

Table 7 Window dimensions

H – height of the window(s), m;

A – are of the window(s), m2

Ecotect has shown that the peak heat gains for base case scenario happens on April 22nd at 15:00, thus, at first, the solar heat gains were investigated manually at this time. The altitude is

. Initial shading device has the length of 1m for library and office floors.

The Figure 15 shows that when the altitude is

, only the second floor glazing is fully

shaded. The small upper part of the window at the second floor is not shaded and permits some of the direct sunlight. The first floor is not shaded at all.

Figure 15 Initial shading device and shading on April 22nd 3pm

The un-shaded area on the west façade of second floor:

Where: 

A is the non-shaded window area of 2nd (library) floor



L’ is the total length of windows on the west side of 2nd floor



H is the height of the window above the shading device on the 2nd floor

Thus, the total shaded and non-shaded area of the windows for west side of the building is represented in the Table 8.

Altitude Shaded Area (

) non-shaded area (

1st floor (Exhibition centre) 59.1

72.9

2nd floor (library)

59.1

49.9

23.0

3rd floor (office)

59.1

72.9

122.8

95.9

Total

)

Table 8 Shaded and non-shaded area of west sided facade

Where: 

Shaded area is the sum of the shaded glazing area for each side



Non-shaded area is the west glazing area in total (east side is fully shaded)



Load – the solar load for the specific time used taken form the tables ( Appendix1).



Load’ – the lowest solar load for the shaded area at that time.



The correction factor of 0.92 was chosen for the clear window and a slow response building.

Tables 9 and Table 10 represent the results for the solar gains on April 22nd. West side

East side

Time Shaded Load NonArea (

(

)

Load Solar

Shaded Load solar

shaded (

gain

Area

(W)

(

)

heat )

gain (W)

)

14:30 123

101

353

42559 114

101

10655

15:30 123

481

53064 114

9916

Table 9 Calculation of solar heat gains on April 22nd

Total solar gains Time

14:30

53214

15:30

62981

Table 10 Solar heat gains on April 22nd

°C

MONTHLY DIURNAL AVERAGES - SINGAPORE, SGP

W/ m²

1.0k

However, it has been found that the results for the peak solar heat gains were 30

0.8k

been suggested the weather change during that day which could cause a cloud

0.6k

cover blocking of some of the solar energy. It could be seen in the Figure 16

0.4k

two dips are visible at around 11:00 and 14:00 o clock obtained from the

0.2k

different from those got after Ecotect simulations. The reason for that has

Ecotect weather tool. At those times the clouding has increased substantially. -10

Jan

Feb

Mar

Apr

May

Jun

°C

LEGEND Comfort: Thermal Neutrality Temperature Rel.Humidity Wind Speed

Direct Solar Diffuse Solar Cloud Cover

Jul

Aug

Sep

Oct

0.0k

Nov

Dec

DAILY CONDITIONS - 22nd April (112)

W/ m²

1.0k

0.8k

0.6k

0.4k

0.2k

-10

Figure 16 Solar irradiation on April 22nd

Thus, in order to check that Ecotect is reliable and if the assumptions are wrong in calculating solar heat gains, an additional calculation was performed manually, but for other date. The further calculations for solar gains at 13:00 on December 31st were chosen for comparison where there no great variations of the solar irradiance. Solar heat gains (2) At December 31st 13:00, the upper window part of a west sided second floor is partly shaded as shown in Figure 17 West side shading of the building on December 31st 1pm . Moreover, the east façade of the building is also fully shaded. Calculations:

0.0k

where:  

is the vertical length of the shaded area as shown in the Figure 17 . l is the length of shading device = 1m



is the altitude at 66.8 at 13:00 on December 31st

Thus,

is equal to 2.33m.

Figure 17 West side shading of the building on December 31st 1pm

The, non-shaded area of the west façade 2nd floor:

Where: 

A is the non-shaded area for 2nd (library) floor



L’ is the total length of windows in west side of 2nd floor



H is the height above shading device in the 2nd floor which is non-shaded Shaded

non-shaded

(

Altitude

y (m)

66.8

2.3

72.9

2nd floor (library)

66.8

70.6

2.3

3rd floor (office)

66.8

2.3

72.9

143.5

75.2

1st floor (Exhibition centre)

Total

)

Table 11 shaded and non-shaded area for west side

Total solar gains for the second case: Total

Thus, the calculation for solar heat gains is represented in Table 12 Calculation of solar heat gains on December 31st and the final value is shown in Table 13 Solar heat gains on December 31st. est side

East side Non-

Time

solar

Shaded Load

solar heat

Shading Load

shaded Load heat

Area

(

)

( )

(

)

gain )

)

( )

gains (W)

(W)

12:30 143.5

102

5.2

172

25366

114.7

181

19094

13:30 143.5

102

75.2

28064

114.7

153

16140

Table 12 Calculation of solar heat gains on December 31st

Total solar gains Time W

12:30 44461.1

44.4

13:30 44205.7

44.2

Table 13 Solar heat gains on December 31st

The results, comparison and discussion between the results of Ecotect and manual calculations will be presented on the following sections after the manual calculations of fabric and ventilation heat gains 2.1.3 Fabric Heat Gains The manual calculations for fabric heat gains follow a simple procedure and the properties of the base case building materials were investigated. The results are presented in the Table 14.

Where: 

Q is the fabric heat gains, W



U is U-value for the particular building material, W/m2K



is the temperature difference between the outside and inside Inside Temp

outside

U-value

Temp

(

Area of )

wall (

)

Q (W)

Walls

32.9

3.89

1177

31602

Windows

32.9

5.1

333

11728

Roof

32.9

4.16

979

28106

Total

71438 = 71.4kW

Table 14 Fabric heat gains

Heat flux through floors is neglected here due to the small/no temperature differences between them and the soil. 2.1.4 Ventilation Heat Gains Ventilations flow rate was calculated using know number of people in the building and providing 10 l/s of fresh air for each person. Afterwards mass flow rate was calculated by multiplying air flow rate with density of air at 26.5°C and 70% relative humidity. This inside temperature was chosen as an approximation because temperature in the exhibition hall is 26°C while in other zones it is 27°C, while the outside temperature according to the weather data is 32.9°C with humidity of 59%. Afterwards enthalpies of 25

inside and outside air were found using psychrometric properties calculator (http://www.sugartech.co.za/psychro/index.php). Finally, ventilation heat gains were found multiplying enthalpy difference by mass flow rate. Volume flow

Number of

rate per person,

people

l/s

533

Total volume

Air density at

Mass flow rate,

flow rate, m3/s

26.5°C

kg/s

5.33

1.15

6.1

Table 15 Mass flow rate

Temperature, °C

Relative

Enthalpy,

humidity, %

kJ/ kg

Inside

26.5

65.51

Outside

31.9

80.89

Table 16 Enthalpies in inside and outside

Enthalpy

Mass flow

Heat gains,

difference

rate, kg/s

15.4

6.1

Table 17 Total ventilation heat gains

2.2 Comparison between Ecotect and Manual Calculation Results The manual calculations and simulations using Ecotect have been done. The results are presented in the Table 18.

April 22nd, 3pm

Ecotect

Manual calculation

Fabric heat gain(kW)

Solar heat gain (kW)

114

141

gains, kW

Solar heat gain (kW)

Internal heat gain (kW) Ventilation heat

December 31, 1pm

Table 18 Comparison between Ecotect and manual calculation results

The discussion on the difference between the results: 

Fabric heat gains are higher with Ecotect but it uses admittance method while we used simple calculations with just U-values and we ignored heat flows through ground floor.



Solar heat gains are lower for Ecotect than manual calculations. Initial hypothesis for the difference was data used for solar heat gains, Ecotect uses weather file according to the actual weather, while we used solar heat gain table what provides the highest solar heat gains at specific location and file. Although, the different situation was checked at another time, the difference between Ecotect and manual calculations was still a significant. However, afterwards difference in correction factor was noticed, Ecotect uses 0.47 for heavyweight and 0.64 lightweight building. If we used the lightweight value for manual calculations heat gains on April 22nd would have been 39.7 kW and 30.5 kW on December 31, hence difference is really small.



The value for internal heat gains from Ecotect differ from manually calculated total internal heat gains. However, it is possible that Ecotect does not take latent heat gains into account for this calculation. (manually calculated sensible heat gains 110kW, Ecotect calculated just the slightly higher value - 114 kW)



Solar heat gains from manual calculations are used as an average between the two values: half hour before and after the given times. This was done because the exact time value was not available from the solar irradiance tables.



The only very similar value has been obtained for the ventilation heat gains.

Results provided by Ecotect and manual calculation suggest that the model is accurate, and difference in values arise from different assumptions and methods used, and data (weather file or solar gains table).However, the difference is relatively small and it is safe to assume that the model is good for further investigation.

2.3 Thermal Performance Investigation Using Ecotect The energy performance simulation of the building is to test the initial design of the building (simple one) and then introduce improvements and changes in design materials of the building. The idea is to compare the initial design performance to the retrofit of the building which will have the best combination of materials chosen. The different materials will be considered for the different design stages. Each of the design stage will be simulated in the Ecotect and the most appropriate one will be chosen as a final retrofit design. In addition to redesigning of the building, the window shadings will be considered and added where needed. 2.3.1 Model Model of the building was created using building design software – Ecotect. It is enough to consider only three zones (each floor treated as a zone) as it provides average temperature in the building and cooling requirements for each zone in a simple represented model. Also, the external stores and toilets were not considered. In order to have an accurate volume of the zones and represent gaps between the floors, as can be seen in cross section drawing, we made zones by internal boundaries of the floors and set interzonal adjacencies so Ecotect could understand that they are adjacent. The top roof is considered to be separate and can be treated as a shade for the building. Initial model can be seen in Figures 18 and 19.

Figure 18 Base case building 1

Figure 19 Base case building 2

2.3.2 Zone Settings

CIBSE Guide A, 2006 was used to get guidance about conditions and heat gains in the building. Exhibition Centre (treated as meeting/conference room or bar/restaurant): 

Density 3m2/person



Activity- walking



Temperature up to 26



Sensible heat gains: equipment and lighting 25W/m2. People 80 W/person (27W/m2)



Latent heat gains 20W/m2

Library: 

Density 10m2/person assumed



Temperature up to 27



Sensible heat gains from lighting and equipment 15W/m2 assumed. People 70W/person (8W/m2)



Latent heat gains 6W/m2

Office: 

Density 10 m2/person



Temperature up to 27



Activity - sedentary



Sensible heat gains: from lighting and equipment 30W/m2. People 70W/person (8W/m2)



Latent heat gains 6w/m2

Assumed schedule for all zones 7am-6pm 100% occupation. That represents the worst case scenario for highest possible heat gains as solar gains occur during daytime. However, it is not accurate assumption for total energy consumption as occupation at exhibition centre is very unlikely to be that high all the time and probably it would be more occupied in the evening. There is possible variation in occupation in the library and office as not all people spend all this time at the office. Clothing: 1 clo Lighting is 400 lux on all working plane. That represents worst case scenario and gives room for improvements as individual task specific lighting. 2.4 Optimization of Design Variables In order to optimize design variables as materials and shading used annual load table with monthly averages were used and all values summed up i.e. all the values from Table 19 were summed up and compared in order to reduce total heat gains. Each variable was treated separately that allows getting to the best result even if they contribute to reduce the same gains e.g. shading and glazing both reduce direct solar gain but were treated separately.

ANNUAL LOADS TABLE Direct Solar Gains - Qg All Visible Thermal Zones - Monthly Averages HOUR

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

(Wh)

-----

------

635

585

727

1484

1629

1244

896

848

2243

3342

2653

1312

8549

9167

10822

12237

12543

10651

10493

9544

12339

15525

12903

10902

17785

19741

19950

21497

21022

17174

19085

17562

18962

21444

19338

17639

22429

22986

24831

24672

25176

21495

22276

22833

23248

24325

23327

21190

24899

26927

25157

26417

25648

23980

25017

25513

23623

23587

25279

23027

24044

24560

22548

22357

22186

21599

22185

23476

20411

22065

22442

22532

20632

22041

19881

20226

18940

18782

18697

20628

18697

19787

19741

21023

23714

23018

22260

22923

23354

23600

22196

22361

21606

23568

22845

21639

24261

26897

25951

28426

24384

25370

25308

24108

28294

21777

21421

21955

21658

22040

24716

20029

20863

22185

22571

20579

24404

17440

18222

19838

16588

17466

21554

16609

14002

15747

18252

14757

18240

9761

10072

12773

3761

5944

5196

3235

1682

2431

4239

2472

2083

714

704

1593

Table 19 Example of annual load table with monthly averages

2.4.1 Shading CASE 1 - Initially shading was provided for first and ground floors (1 meter wide across the West facade top being 0.7 meters below top of the window and 0.5 meters apart) on the West side while in the east corridor provided quite a lot of shading.

Figure 20 Shading - case 1

Design improvements: CASE 2 - Provided the same shading for the ground floor on the West side

Figure 21 Shading - case 2

CASE 3 - Added one more shading louver on the West side (additional layer is 0.5 meters above old shading device and 0.2 meters below the top of window.)

Figure 22 Shading - case 3

CASE 4 - Added shading as railing on the East side.

Figure 23 Shading case - 4

CASE 5 - Design with no shading devices at all

Direct solar gains, kWh

CASE 1

CASE 2

CASE 3

CASE 4

CASE 5

2517

2322

2135

2956

Table 20 Direct solar gain dependency on shading device

Direct solar gain dependency on shading device 3500 Heat gains, kWh

3000

2956 2517

2500

2322

2135

2000 Direct solar gains

1500 1000 500 0 CASE 1

CASE 2

CASE 3

CASE 4

CASE 5

Figure 24 Direct solar gains dependency on shading device

Case where no shading is present is taken into consideration as well. It can be seen from the Figure 24 and Table 20 that the best option is to have three louver shading device on all three floor and that addition of rails for the East side does not make any difference. Hence our selection is to have three louver shading on all three floors. 2.4.2 Windows The properties of the windows are selected so that a maximum light transmittance, a minimum solar heat gain coefficient and U -value is achieved. The most suitable type of the windows is to be decided based on those criteria. Priorities are: 33



Maximised daylight levels (high visible transmittance, ideally higher than 0.6)



Minimized solar heat gains (low solar heat gain coefficient SHGC, ideally lower than 0.4)



Maximised thermal insulation to minimise the heat flow from outside to inside the building (low U-value)

However, before doing a research on the state-of-the-art windows for the highest energy efficiency, two additional cases have been suggested to represent simple and more conventional window configurations. CASE 1 (BASE CASE) - typical single glazed window A very simple window configuration has been chosen for the initial design stage. It comprises of a single glazed unit with timber framing. The key properties are:  Visible Transmittance (VT) = 0.737  Solar Heat Gain Coefficient (SHGC) = 0.94  U - value = 5.1 W/m2K

CASE 2 - typical double glazed window A typical double glazed unit has been introduced. This is more likely to be encountered in most buildings and is made of the two glass panes separating air cavity. The frame is timber and the key properties are presented as follows:  VT = 0.647  SHGC = 0.81  U - value = 2.9 W/m2K

CASE 3 - final, highest performance window The various manufacturers’ catalogues have been checked in order to find a best suitable window to use in Singapore. The windows that could be used to improve energy performance of the building considerably are represented below: 34

1. Double-Glazed with Low-Solar-Gain Low-E Glass and argon fill: VT = 0.64; SHGC = 0.27; U = value 0.24 W/m2K

2. Double-Glazed with Moderate-Solar-Gain Low-E Glass and argon fill: VT = 0.70; SHGC = 0.39; U-value = 0.25 W/m2K

3. Triple-glazed*, Low-Solar-Gain Low-E Glass, Argon/Krypton gas fill: VT = 0.56; SHGC = 0.33; U-value = 0.13 W/m2K

4. iWindow 7 Low Solar Heat Gain: VT = 0.57; SHGC = 0.34; U-value = 0.14 W/m2K

According to the key evaluation criteria in choosing the best window a stated earlier, the number 2 window has been selected so that a relatively low U-value and SHGC is obtained while preserving high visible transmittance for visual comfort and daylight purposes. Thus, the window selected provides both significant thermal insulation and day lighting levels inside the building and the key material properties defined are:  VT = 0.64  SHGC = 0.27  U - Value = 0.25 W/m2K

References: 1.http://www.efficientwindows.org 2. http://www.pilkington.com/products/bp/bybenefit/solarcontrol/suncool/literature.htm 3. http://www.efficientwindows.org/glazing_.cfm?id=10 4. http://www.seriouswindows.com/commercial/products/retrofit-glass-system.html 2.4.3 Thermal Evaluation of Windows The most affected areas by glazing are direct solar heat gains, fabric heat gains and light transmitted to the building. It can be seen that case 3 windows provide the best thermal

performance; moreover it has nearly the same visual transmittance (0.64 while case 1 has 0.737). Hence case 3 windows are chosen for further consideration. CASE 1 (base)

CASE 2

CASE 3

Direct solar

2517.47

1489

847

Fabric heat gains

3673.647

3357

3011.044

Table 21 Direct solar and fabric heat gains dependency on windows

Direct solar and fabric heat gains dependency on windows 4000

3673.647 3357

Heat gains, kWh

3500 3000

3011.044 2517.47

2500 2000

Direct solar

1489

1500

Fabric heat gains 847

1000 500 0 Case 1 (base)

Case 2

Case 3

Figure 25 Direct solar and fabric heat gains dependency on windows

Note: total fabric heat gains are represented in both Table 21 and Figure 25.

2.4.4 Retrofit of Building Envelope and Internal Surfaces The selection of the materials takes into the account several things. First of all, it has been decided to look for alternatives of conventionally accepted building insulation configurations. That is to research on the insulation widely used in Singapore which could be applied for the building retrofit. Secondly, the state-of-the-art materials have been investigated on the market. Thus, a reduction in building energy needs could be maximised. Finally, the outside and inside surfaces, as well as finishes have been considered so that low energy demand and comfort levels are maximised. This takes into the account a different surface reflectance. Thus, the retrofit of the building materials focuses on the state-of-the-art design procedures and is the key to minimize the energy usage and increase comfort levels in the building.

2.4.5 Selection of Thermal Insulation Material for Retrofit Aerogel insulation provides very low thermal conductivity values, typically around 0.014 W/mK, and is mostly suitable for high performance building insulation purposes. Therefore, as it is thought to be the best, revolutionary solid state insulation material, having thermal properties close to vacuum panels, it has been used for retrofit of the building in Singapore. The silica aerogel is sold as a blanket of a thickness either at 5mm or 10mm. Thus, a combination of the ThermablokSP Aerogel Blanket product can be applied practically at any extent. Other benefits include: 

Significant saving in energy costs



Unaffected by moisture, mould or water



Easily applied via stick-on back.



"Class A" fire rated



Economical



Adds acoustical isolation



Virtually no weight means low cost shipping



Super insulating silica aerogels exhibit the lowest thermal conductivity of any solid known



Low thermal conductivity, high strength



Environment friendly, no toxicity, non-corrosive



Good properties of compressive resistant, shock resistant and sound insulation



Wide service temperature and application field.

The physical properties of the aerogel are as provided:  thermal conductivity - 0.014 W/mK  density approx. 185 kg/m3  specific heat capacity - 0.950 kJ/kgK 37

Thus, silica aerogel has been chosen as a main thermal insulation material to be used in the retrofit of the building components. References: 

http://www.thermablok.co.uk/products/thermabloksp-aerogel-blanket



http://www.thermablok.co.uk/wp/wpcontent/uploads/2012/07/thermabloksptechdata.pdf



http://aerogels.en.ec21.com/Aerogel_Thermal_Insulation_Panels-4177198_4177258.html



http://www.aerogel.com/products/pdf/Pyrogel_6650_DS.pdf



http://www.engineeringtoolbox.com/specific-heat-solids-d_154.html

2.4.6 Walls

The wall insulating materials are to be added to the base concrete material in order to improve thermal insulation of the building as well as minimizing indirect solar heat gains. The various combinations of materials could be chosen and added either on the inside or outside of the building surfaces. Ideally, the addition of insulating layers to the external wall surfaces should be considered in order to have a little/no effect on the spaces inside the building.

The external and internal wall finishes are to be reflecting. This is to do with lowering indirect solar heat gains and maximising lighting levels inside the building respectively. Those materials/finishes typically are light in colours and provide good reflectance.

Because the night-to-day temperature swing is rather small, materials with high thermal mass (high heat-storage capacity) are of little benefit, but they can be used to minimize indirect solar heat gain effect to the inside of building.

Thus, the retrofitting of the wall materials considers: 

A good thermal insulation



A good indirect solar energy shading



A well designed finishes for improved lighting levels and comfort 38



A proper structural integrity



A minimum resource use (where appropriate, if possible)

2.4.7 Wall Elements

In order to choose a best material combination, several different wall elements have been chosen for evaluation, including the base case scenario. The thermal insulation materials were found available on the market and the final wall compositions are represented below. CASE 1 (Base case):

Figure 26 Case 1 wall - structure

Layer name

Width,

Density,

Heat capacity,

Conductivity,

kg/m3

J/kgK

Wm/K

1. Dense concrete

100

2200

840

1.7

2. Gypsum

1100

840

5.56

plasterboard Table 22 Case 1 wall - elements

U value,

Admittance

Solar Absorption,

Decrement

Thermal lag,

W/m2K

Factor

3.89

4.890

0.495

0.81

Table 23 Case 1 wall - key features

CASE 2 - conventional retrofit:

Figure 27 Case 2 - wall structure

Layer name

Width, mm

Density,

Heat

Conductivity,

kg/m3

capacity,

W/mK

J/kgK 1. Brick Masonry Medium

110

2000

836.8

0.711

2. Air Gap

1.3

1004

5.56

3. Dense Concrete

100

2200

840

1.7

4. Plaster Building (Molded

1250

1088

0.431

Dry) Table 24 Case 2 - wall elements

U value,

Admittance,

Solar Absorption,

Decrement

Thermal Lag,

W/m2K

Factor

1.68

5.73

0.559

0.02

7.8

Table 25 Case 2 - wall key features

CASE 3 - Super insulating retrofit:

Figure 28 Case 3 - wall structure

Layer name

width,

density,

heat capacity,

Conductivity,

kg/m3

J/kgK

W/mK

1. Weatherboard

650

2000

0.14

2. Silica Aerogel

100

185

950

0.014

3. Dense

100

2200

840

1.7

4. Silica Aerogel

185

950

0.014

5. Plasterboard

950

840

0.16

Concrete

Table 26 Case 3 - wall elements

U value,

Admittance,

Solar Absorption,

Decrement

Thermal Lag,

W/m2K

Factor

0.09

0.8

0.276

0.02

14.75

Table 27 Case 3 - wall key features

The colour reflectance values for internal and external surfaces have chosen to be 0.8. Fabric and indirect solar heat gains in each case can be seen from Table 28 and figure 29. There is a significant difference between case 1 and other two options. However, there is a small difference between case 2 and case 3 that raises a question if it is worth it to have very well insulated wall with two layers of aerogel.

CASE 1

CASE 2

CASE 3

Building fabric heat gains, kWh

3674

520

494

Indirect solar gains, kWh

1799

305

289

Table 28 Fabric and indirect solar heat gains dependency on wall

Fabric and indirect solar heat gain dependency on wall 4000

Heat gains, kWh

3500 3000 2500 2000

Building fabric heat gains

1500

Indirect solar gains

1000 500 0 CASE 1

CASE 2

CASE 3

Figure 29 Fabric and indirect solar heat gain dependency on wall

2.4.8 Floors and Ceilings

The building floors, including the ground floor and upper floor slabs, do not need a high thermal insulation rather than provide a good structural integrity and adequate sound insulation. However, the latter is not to be covered in this report and most of the details will be given for designing floor surface layers which can provide different reflectivity. The thermal insulation has not been considered due to the more or less similar temperatures throughout the building zones/floors: that is no heat flux. The ground flooring is in touch with the soil and temperatures of the earth should not make much difference to the building temperatures.

The building has suspended ceilings where the voids are used for installation of building services. The surfaces of the ceiling are to be decided so that a good light reflectivity is achieved in order to have a good illumination of the spaces inside the building. Typical surface coatings are light in colour with good reflectance values. 42

Thus, the retrofitting of floors and ceilings aims to: 

Keep the base structure intact



Improve surfaces by adding light reflective coatings/paints



Install finishes so that a comfort inside the building increases

2.4.9 Floor and Ceiling Elements The only two cases have been considered: the base case and final-retrofit case. CASE 1 (BASE CASE) Ground floor:

Figure 30 Ground floor structure

Layer name

Width,

Density,

Heat capacity,

Conductivity,

kg/m3

J/kgK

W/mK

1. Carpet

200

1360

0.06

2. Dense concrete

300

2200

840

1.7

1500

1300

1046

0.837

slab 3. Soil

Table 29 Ground floor elements

U value,

Admittance,

Solar Absorption,

Decrement

Thermal Lag,

W/m2K

Factor

0.45

3.71

0.467

4.6

Table 30 Ground floor key features

Internal floor/ceiling partitions:

Figure 31 Internal floor structure

Layer name

Width,

Density,

Heat capacity,

Conductivity,

kg/m3

J/kgK

W/mK

1. Carpet

200

1360

0.06

2. Dense concrete

300

2200

840

1.7

slab Table 31 Internal floor elements

U value,

Admittance,

Solar Absorption,

Decrement

Thermal Lag,

W/m2K

Factor

2.2

3.72

0.467

0.29

4.6

Table 32 Internal floor key features

CASE 2 (retrofit) The materials used for both ground floor and floor partitions have not been changed. The internal finishes were only considered to be added. For instance, as it has been mentioned it is only necessary to increase colour reflectance values for floor and ceiling in order to increase the lighting levels inside the building. There is low/no heat flux across the floor and ceiling structures thus reflectance has been increased from 0.59 to 0.8 for both ceiling and floors surfaces. This means that internal finishes will appear light in colour whereas it is painted or applied with other light materials.

Type of the surface

Base case colour reflectance

Retrofit colour reflectance

Floor

0.59

0.8

Ceiling

0.59

0.8

Table 33 Floor and ceiling reflectances

2.4.10 Roof

The addition of insulating materials on the base roof concrete layer is considered thus that a reasonably high thermal insulation is achieved. Moreover, a sun reflecting and water resistant materials are to be installed in order to prevent high indirect solar heat gains as well as sealing the building to prevent any water penetrating through the roof structure in the rainy climate. Thus, the retrofitting of the roof takes into account: 

An improved thermal insulation



High solar energy shading with longer thermal lag



A high solar reflectance



A proper roof sealing

2.4.11 Roof Structure Cases The two cases have been introduced for better building energy analysis: the base case and retrofit case. The base case scenario represents typical roof materials, while the retrofit adds the same super insulation (aerogel) as it was used for walls. CASE 1 (base case)

Figure 32 Case 1 - roof structure

Layer name

Width, mm

Density,

Heat capacity,

Conductivity,

kg/m3

J/kgK

W/mK

1.Bitumen membrane

N/A

2. Dense concrete slab

300

2200

840

1.7

Table 34 Case 1 - roof elements

U value,

Admittance,

Solar Absorption,

Decrement

Thermal Lag,

W/m2K

Factor

2.82

5.81

0.725

0.35

0.7

Table 35 Case 1 - roof key features

The bitumen thermal properties have not been considered as it can be negligible. As the bitumen is black in colour it has a high solar absorption. However, the building has its own shading (curved shelter) thus a retrofit will focus on the thermal properties as well as the thermal lag. CASE 2 (retrofit)

Figure 33 Case 2 - roof structure

Layer name

Width, Density,

Heat capacity,

Conductivity,

kg/m3

J/kgK

W/mK

1.Bitumen membrane

N/A

2. Silica aerogel

100

185

950

0.014

3. Dense concrete slab

300

2200

840

1.7

Table 36 Case 2 - roof elements

U value,

Admittance,

Solar Absorption,

Decrement

Thermal Lag,

W/m2K

Factor

0.13

5.81

0.725

0.08

13.6

Table 37 Case 2 - roof key features

Moreover, the internal surface (ceiling) has been set having a high reflectivity finishing. The colour reflectance has been increased from 0.5 to 0.8 which should increase the lighting levels inside the building. Comparison for roof material has been done along with two options of walls CASE 2 and CASE 3 to see how it looks like in contrast and it is represented in Table 38 and Figure 34.

Heat gains

Building fabric, kWh Indirect solar, kWh

Normal roof and

Normal roof

Aerogel wall and

aerogel wall

and cavity wall aerogel roof

aerogel roof

CASE 1

CASE 2

CASE 3

CASE 4

494

519

289

305

Table 38 Fabric and indirect solar heat gains dependency on roof along with cavity and aerogel wall

Roof consideration 600

Heat gains, kWh

500 400 Building fabric

300

Indirect solar

200 100 0 CASE 1

CASE 2

CASE 3

CASE 4

Figure 34 Fabric and indirect solar heat gains dependency on roof along with cavity and aerogel wall

Cavity wall and

Other notes: Ecotect does not provide calculation results for thermal lag. Therefore, an external software program has been used which defined the needed building element properties for the retrofit of building materials. 2.4.12 Internal Heat Gains Internal heat gains contribute to 60% of total heat gains in our base case model and it is one of the most difficult to reduce as it has heat gains from people and equipment. It is not really possible to reduce heat gains from people, the building is built for people and they are going to emit heat, even though in reality they are likely to be significantly lower as in the model exhibition centre was considered to be densely occupied throughout a day as well as number of people is likely to often be lower in the library and office. Heat gains from equipment can be minimized by choosing more efficient appliances, using lighting smartly and exploiting daylight and promoting smart use of energy. In the pie chart in Figure 35 base case internal heat gains by type can be seen. We can see that around a third of gains come from people and that part cannot be reduced. However, all equipment except lighting is contributing to around a half of internal heat gains and that can be sector where most results could be achieved. Lighting heat gains are tackled in another section, while possible reduction in other equipment heat gains is considered here. For our initial model typical values for equipment heat gains in offices were used from CIBSE Guide A, 2006. However, they represent typical values and we can aim for more. Moreover, computers are significant contributors to heat gains in offices and efficiency of computers has improved a lot since the guide has been written 7 years ago. E.g. heat gains for computers suggested by the CIBSE Guide are 155 Watts for 20 inch screen computer, while current models of 21 inch screen computer have nameplate power consumption of 100 Watts or if laptops are used power consumption can be even two times lower.

Internal heat gains, kW 21 42 People Equipment-lighting Lighting 71

Figure 35 Internal heat gains distribution by source

Basic assumptions for our improved model are: 

Each person in the office has one of computer running at full power at all times with no diversion. (10kW)



Four continuously running laser printers, three in the office and one in library. (2kW)



Lighting remains the same



Heat gains from cafe continuous (5kW)



Additional heat gains from other equipment like projectors, kitchen appliances in the office, etc. (5kW for each floor)

Additional heat gains are the most difficult to estimate, as they are not really predictable and depend on occupants. However, assuming additional continuous heat output provides reasonable accuracy. Moreover, the assumption about all computers running at full power all the time is unrealistic, hence provides some allowance for other heat gains. These assumption would reduce heat gains from equipment from 71 kW to 38 kW (reduction by 33kW or almost by a half) and it is represented in Figure 36.

Improved internal heat gains, kW People 5 Lighting 21 42

Four photocopiers continuosly printing Additional equipment

10 2

Computers 21 Café

Figure 36 Improved internal heat gains distribution by source

2.5 Comparison between Base Case and Improved Model Figure blah represents monthly heat gains with our initial and improved models. The table represents that numerically and provides information about peak heat gains, total heat gains and heat gains per square meter per year. Peak heat gains were reduced significantly by more than one third from 308 kW to 200kW and total heat gains per year were reduced by 268 MWh ( by 31%). Moreover, heat gains through the building envelope were almost eliminated, leaving only optimized heat gains that are necessary like equipment, people, lighting and ventilation.

Monhly heat gains 90000 80000 70000 60000 50000

Base case

40000

Improved model

30000 20000 10000 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Figure 37 Monthly heat gains, base case and improved model

Base case Improved model Max cooling load, kW

308

200

Jan

68139

46888

Feb

65908

45096

Mar

75168

51785

Apr

76386

52325

May

76379

52223

Jun

75918

51951

Jul

74807

51247

Aug

73587

50762

Sep

68411

46943

Oct

72316

49858

Nov

64502

44645

Dec

65208

45147

856733

588876

282

193

Monthly cooling loads, kWh

-----------Total Heat gains, kWh -----------Per m²

Table 39 Max cooling load, total heat gains and monthly heat gains for base case and improved models

2.6 Ventilation As assumed in stage 1, the air flow rate is

Where: Air flow rate is in unit of m3/s Population

Air flow rate (m3/s)

Exhibition

337

3.37

Library

101

1.01

Office

101

1.01

Table 40 Fresh air requirements for each floor

Ventilation is a primary contribution to the occupants’ satisfaction. And the growing focus on energy consumption attracts more interests. Ventilation is supposed to satisfy three requirements: health, cooling and comfort. This is a basic assumption for each floor. But the air change rate differs from different specific zones. For example, the extract rate for kitchen in office is higher than other space. 2.6.1 Natural Ventilation The option of using natural ventilation in this building was not particularly appealing for several reasons. The temperature and humidity levels of the air in Singapore are relatively high throughout the year. Also, the air quality is not considered the best as Singapore is densely populated country. So the processing of the ventilated air is necessary to provide both the desired indoor temperature and air quality. Furthermore, as shown in Stage 1, the wind speeds are mostly quite low and the direction of the wind changes throughout the year. So, not having a fixed wind direction and adequate wind speed, along with the necessity for the air processing, makes using natural ventilation a second choice. 2.7 Daylight Investigation for Base Case The use of daylight in buildings can always reduce its operating costs as it can provide both heating and illumination, reducing the use of electricity and fossil fuels. Apart from these benefits, daylight is also more preferable by the occupants, as it provides a link to the outside environment. It is also proven that employees are more productive when working with daylight rather that artificial lighting. In our case, because of the hot climate of Singapore, solar heat gains needed to be avoided in order to maintain cooling costs low. At the same time, daylight can reduce lighting costs. So the window area and design needed to be optimised to achieve both low energy consumption and high occupancy satisfaction. A daylight simulation was executed for each floor using Ecotect in order to obtain the mean daylight levels and daylight distribution. The results showed that daylight alone could not be employed for adequate illumination when compared to CIBSE guide A standards for lighting levels. The required lighting levels for the exhibition centre, library and office are 300, 500 and 500 lux respectively. Although the mean light levels seemed satisfactory, the distribution of light was uneven, with the areas near the windows being 52

much brighter and the areas close to the centre being insufficiently lit (around 250lux). The solar heat gain values were also calculated using Ecotect in order to obtain the energy consumption for cooling for the existing window area. The total direct solar heat gains over a year were found to be 75525kWh. With a COP of 3 for the air conditioning system, the electricity consumption was 25175kWh.

Figure 38 Daylight levels for ground floor

Figure 39 Daylight levels for 1st floor

Figure 40 Daylight levels for 2nd floor

Thorn Line XS luminaires were chosen which contain two T16 fluorescent lamps each producing 2600 lumens. Total power consumption for each luminaire is 63W. The surface reflectivity for floor, walls, and ceiling are 0.5, 0.2 and 0.5 respectively. The mounting height was calculated to be 2m. Using RI =

for the room index gives RI = 5.57,

6.18 and 6.62 for ground 1st and 2nd floor respectively. W was different for each floor as the area in need of lighting was different. The utilization factor (UF) value was taken from the Line XS luminaire table UF = 0.74. A surplus of 55 lux for the ground floor, 230 lux for the first floor and 290 lux for the second floor were required to cover the lighting needs not satisfied by daylight alone. Using the formula n =

and the appropriate area

for A (as shown in the figures below) the lamps number was found to be 28 for ground floor, 130 for first floor and 180 for second floor. Total electrical consumption = (14+65+90) 63 = 10647W. Annual consumption (working hours) = 10647

365 =

42748kWh. The total annual electricity consumption was then summed up to give 42748 + 25175 = 67923kWh

Figure 41 Ground floor area needing surplus lighting

Figure 42 1st floor area needing surplus lighting

Figure 43 2nd floor area needing surplus lighting

Assuming zero glazing and using only fluorescent lamps for lighting, the electrical consumption was calculated over a period of one year. This was done in order to obtain the increase or decrease in energy consumption with the absence of daylight. Again the same formulae as before were used with the same illuminance standards. The total number of luminaires was 423 giving an electrical power consumption of 26649W. Total annual electricity consumption = 26649 × 11 × 365 = 106996kWh. This value proved that maintaining a large window area would actually save electrical energy. 2.8 Renewables Renewable energy is the energy obtained from continuous or repetitive currents of energy recurring in the natural environment [1]. Nowadays, the idea of zero energy buildings is not an odd concept. Zero energy building does not mean that the building should run without any energy; in order to have a ‘’zero energy’’ building, the net energy consumption has to be zero. In other words, there must exist alternative sources of energy, to create clean energy, to even out the energy consumptions in the building. There are various kinds of renewable energy technologies that can be integrated into the built environment, such as wind turbines, solar thermal collectors and photovoltaics. However, not all of them are suitable in every circumstance, since all the renewable energies are location and/or weather dependant.

2.8.1 Sources with Limited Potential According to National University of Singapore’s Energy Studies Institute, not much hydro or geothermal energy sources are available in Singapore [2]. Hydro Singapore has a relatively flat coastline with most of its land less than 15m above sea level, which makes it not so effective for hydropower; and much of the coastal areas are used for ports, anchorage, and shipping lanes, which limit the application of ocean energy technologies [2]. Geothermal Singapore has twice the geothermal gradient of an average continent, as it can be seen from Figure 44 [3]. However, Singapore is a small, densely urbanised country, so the land space limits its potential.

Figure 44 Singapore's geothermal gradient

Wind As it was mentioned in Stage 1, Singapore has relatively low wind speed throughout the 57

year. Not only the wind speed is not high enough to generate wind power effectively, but also, the direction of the wind changes throughout the year, making it hard to have stability. Biomass Singapore’s neighbouring countries, Malaysia and Indonesia combined account for 80% of world’s palm oil supply [2]. Singapore’s location allows them to have easy access to import biofuels from these neighbouring countries. However, this is not considered as generating the alternative energy of their own. Although Singapore is in the same climate zone, they do not own vast amount of land that serves as bioenergy resources, thus it is hard for Singapore to generate bioenergy. 2.8.2 Integration of Renewables In The Built Environment Looking at a smaller scale, there are more restrains in generating effective amount of renewable energy in the built environment, especially densely populated and urbanised cities like Singapore. Nevertheless, Singapore’s tropical climate allows high amount of reliable solar radiation to be available. Thus using solar power would be ideal in Singapore. There are mainly two types of technologies for retrieving energy directly from the sun: solar thermal and photovoltaics. Solar Thermal Solar thermal energy is the energy from the sun that is absorbed by solar thermal collectors. The solar collectors can be air or water based, and they are in forms of flat plates or evacuated tubes [4]. For domestic hot water heating (DHWS) systems, there are passive and active systems. Passive systems use gravity and the tendency for water to naturally circulate as it is heated through the system without a pump. They are generally more reliable and easy to maintain. Active systems use electric pumps, valves, and controllers to circulate water or other heat-transfer fluids through the collectors [5]. Other types of solar thermal system include concentrating high temperature collectors, such as parabolic troughs, dish system, and central-receiver systems.

There are three main ways that hot water from solar thermal collectors could be used space heating, hot water supply and provide heat for absorption refrigeration system. 58

Space heating is not an option here, as there is no space heating demand. However, it can supply hot water as there is a demand for hot water in toilets or kitchen, hence solar thermal collectors could be used for that. Moreover, passive system could be used as there are no issues associated with water freezing inside the collectors and that would help to reduce electricity consumption. It is possible to use solar thermal energy in absorption refrigeration for air conditioning. However, the weather conditions in Singapore make this particular system unreliable, as it requires a constant heat supply to operate. Such systems are mostly used in areas with constant sunshine and high temperatures. Also, they require quite a large area for the solar collectors to be installed. A more suitable choice for our case would probably be a vapour compression system which uses electricity generated from PVs to operate. Solar Photovoltaics Photovoltaic cells capture direct and diffused sunlight to convert solar energy directly into electricity. The three main types of Si PV cells are monocrystalline, polycrystalline and amorphous thin film, shown in Figure 45 [7]. Among three types, Monocrystalline is the well-ordered structure, most efficient and expensive. These PV cells are put into modules, then panels, covered with a thin layer of anti-reflection coating to minimise light reflection [8]. PV system can be stand alone, with or without a battery bank, or grid connected. The advantages of PV power technology are its reliability due to no moving parts, quick installation, very low operation and maintenance costs, and no fuel is needed [5]. It doesn’t produce noise or atmospheric pollution. It provides power generation where electricity is needed, there are no transmission losses. [13]

Figure 45 Photovoltaics modules

PV panels can be also installed within buildings, referred to as Building Integrates Photovoltaics (BIPV). In BIPV, the power from PV goes to PCU and inverter, and the AC output from PCU goes to building or to grid if supply exceeds demand [5]. Benefits of BIPV are that there is no need for extra land area. There is no need for additional infrastructure; they integrate with other installations. They can be mounted on roofs and façades. Figure 47 [14] shows some options for BIPV installation. The energy generated from the PV panels can supply all or a significant part of building electricity use. Moreover, they can replace conventional building materials, providing an innovative, aesthetic appearance for the building [9]. These advantages of BIPV make it ideal for power generation in our building in Singapore.

Figure 46 Options for BIPV installations

Solar Power Calculation It is possible to make approximate calculations to find out how much energy the system can produce. Monocrystalline Si PV panels will be used to calculate the amount of power the system can produce. Since the technology is improving day by day, the best possible

PV panels in the world are considered to produce additional energy compared to the typical ones. Table 41 shows some of the most efficient available PV panels in the world [10].

Manufacturer

Sunpower [11]

Sanyo Electric [12]

Cell Efficiency

22.5%

17.8%~20.2%

Panel Efficiency

20.1%

15.3%~17.4%

Cell Type

Maxeon Cell Technology

HIT Solar Cell Structure

Size

130 x 130 mm

110 x 110 mm

Power Output Range

225~300 Watts

180~205 Watts

Table 41 Some of the most efficient available PV panels

For our calculation, only the roof area has been considered for how much power can be produced. We assumed a flat roof for the simplification of the calculation.

Available Roof Area: 58m x 25m = 1450m²

Total Annual Incident Solar Radiation Collection: 1627 kWh/m²/year (from Stage 1)

Total solar energy per year for available roof area: 1450m² x 1627 kWh/m² = 2,359,150 kWh (= 2,360 MWh)

In all PV systems, there are system losses due to temperature, shading, dust and debris, etc. [9].System losses of 25% has been assumed. This has to be subtracted from the total. (1 - 0.25) x 2,360 MWh =1,770 MWh This value is then multiplied with the efficiency of the PV panel installed. Three types are considered here. 61

1) Typical Monocrystalline Si PV Panel, Efficiency = 15% 1,770 MWh x 15% = 265 MWh

2) Sunpower Mono-crystalline Silicon, Efficiency = 20.1% 1,770 MWh x 20.1% = 356 MWh

3) Sanyo Electric Mono-crystalline Silicon, Efficiency = 17.4% 1,770 MWh x 17.4% = 308 MWh

It is possible to generate a maximum of up to 350 MWh of energy.

STAGE 3 3.1 Thermal Performance Figures 48, 49 and 50 represent total heat gains and their distribution from different sources: conduction, internal, solar, ventilation and indirect solar gains in the base case model and improved model (with cavity or aerogel wall).

Figure 47 Heat gains breakdown - base case Wh/ m2

GAINS BREAKDOWN - All Visible Thermal Zones

1st January - 31st December

560 70.1%

420

280

140

26.2%

140

Overall Gains/ Losses

280

420

560

700 14th 28th 14th 28th 14th Jan Feb Mar Conduction Sol-Air

28th 14th 28th 14th Apr May Direct Solar

28th 14th 28th Jun Jul Ventilation

14th

Figure 48 Heat gains breakdown – cavity wall

28th 14th Aug Internal

28th 14th 28th 14th Sep Oct Inter-Zonal

28th 14th Nov

28th 14th Dec

28th

Wh/ m2

GAINS BREAKDOWN - All Visible Thermal Zones

1st January - 31st December

560 70.1%

420

280

140

26.2%

140

Overall Gains/ Losses

280

420

560

700 14th 28th 14th 28th 14th Jan Feb Mar Conduction Sol-Air

28th 14th 28th 14th Apr May Direct Solar

28th 14th 28th Jun Jul Ventilation

14th

28th 14th Aug Internal

28th 14th 28th 14th Sep Oct Inter-Zonal

28th 14th Nov

28th 14th Dec

28th

Figure 49 Heat gains breakdown aerogel wall

From the figures above it can be seen that heat gains from sun (as direct and indirect solar) and through fabric were almost eliminated. In the base model it added up to 20% while after improvements it is only 3% while total heat gains were reduced. That means our building fabric and installed shading device are working great together. Windows reduce heat gains from the sun as well as through conduction in the fabric. However, there is no significant difference in the tested wall materials either cavity wall with uvalue of 1.7 W/m2K or it is wall with aerogel and u-value of 0.9 W/m2K, hence there is no point in investing in the aerogel wall and that money could be used to reduce internal heat gains. Moreover, alternative material for roof could also be considered to reduce capital cost. 3.1.1 Internal heat gains Internal heat gains are the main contributor in both base and final cases of our model, they contributed to around 60% of total heat gains at the beginning, while in the improved model heat it increased to 70% after other gains were reduced. Knowing that they consist of gains from lighting, equipment and people, smart use of efficient equipment should be one of priorities to reduce heat gains. Smart use of equipment includes turning it off when it is not used, set short automatic stand by time for computers. Investment in efficient equipment would help to reduce both heating gains

and energy consumption. Moreover it is a better investment than aerogel wall. Of course part of it inevitable, while gains from people cannot be reduced. 3.2 Ventilation The different zones and their functions were taken into consideration in order to calculate the necessary ventilation rates. While the ventilation is crucial in maintaining high air quality, it also accounts for heat gains. The use of heat recovery ventilation can reduce these heat gains by using returning air from inside to cool the air coming from the outside environment, thus saving cooling costs as well. 3.3 Daylight While maintaining the same window area, additional shading was utilised in order to reduce direct solar gains without compromising occupancy comfort. Improved glazing reduced even further the solar heat gains and fluorescent lamps were replaced with Philips LED office modules which provide an even higher efficacy (3400 lm and 40W), minimizing electricity consumption. LED lamps also last longer which saves maintenance costs. The annual direct solar heat gains were reduced to 25410kWh and the electricity consumption for a/c to 8470kWh. A daylight simulation on Ecotect showed very similar results to the base case. However the lighting levels were slightly higher due to the improved internal surface reflectivity. The area in need of artificial lighting was the same so the calculation for the number of LED lamps was performed for the new illuminance value. Those were 30 lux for ground floor, 130 lux for the 1st floor and 210 lux for the 2nd floor. The total number of lamps required was 168 giving a total power of 6720W which is significantly higher compared to 10647W for the previous case.

Figure 50 Daylight levels for ground floor (improved)

Figure 51 Daylight levels for 1st floor (improved)

Figure 52 Daylight levels for 2nd floor (improved)

3.3.1 Further Lighting Improvements In addition to optimising window area, improving wall reflectivity and using energy efficient lamps, other measures can also be taken to further improve both energy consumption and occupancy comfort. The effective control of electric lighting is the key to realising the potential energy saving from daylight. A control system should reduce light output when daylight is adequate and when the space is unoccupied. It ensures that light is provided in the right amount, in the right place for the required time. Several types of control can be utilized. The use of ballasts achieves optimum lamp performance and circuit efficacy. Because most zones of the building have certain operating times, it may be worth to install time switches. Localised switches are very important as well because they allow occupants to use lighting to their liking and more efficiently. Another wise choice would be installing occupancy detectors. Switching off the luminaires after leaving a space cannot always be expected from the occupants. So occupancy detectors use infrared, acoustic, ultrasonic or microwave sensors to detect either movement or noise in the space. They switch off once they have failed to detect occupancy. For the areas closest to the windows, a photoelectric system with daylight linking and dimming would be a good option. Photocells mounted inside the space measure the actual daylight penetration by monitoring the illumination under the first and possibly the second row of luminaires from the window walls. This allows the 67

luminaires to only provide the illuminance necessary to supplement daylight, thus consuming less electricity. Another possible alteration to the building that could increase lighting efficiency is the installation of light tubes (Figure 53), which could provide daylight to the central areas of the floors, with less heat gains.

Figure 53 Light tube

3.4 Renewables Several types of renewable energies were examined. The most reliable was solar energy, as it is the one most available on site. Solar PV panels were chosen to be installed horizontally on the roof, producing electricity for lighting, equipment and even air conditioning. The use of vertical installation of panels can be considered in producing more electrical energy if needed in the future. A separate solar thermal collector can also be used to cover the small needs of the building for hot water.

STAGE 4 4.1 Air Conditioning System Air conditioning system is going to be necessary in the building to ensure occupants’ comfort. Several parameters need to be met for the selection of the air conditioning system for this building. Because this is a large commercial building, there are several different zones, each with different conditions. For example, the office space is constantly populated during daytime, while the exhibition centre can go from zero occupation to very high occupation. Thus, an intelligent system is required, with a central handling unit able to monitor and condition variable zones. The A/C system also needs to be as energy efficient as possible, which means having a high COP. Reliability is an important parameter as well, as it insures low maintenance costs and a long life-time. Moreover, system needs to be good at dehumidification, because the main challenge in Singapore is humid air. Later in the design project cooling and ventilation systems will be designed.

4.2 Realistic Summaries of the Potential Roles of Renewable Energy As mentioned in Stage 2, in order for a building to become zero carbon, it has to create energy to replace the energy consumption in the building. In this case, the solar energy generated from the photovoltaics will produce electricity. This electricity can be used directly by the occupants, such as computers, printers, and lightings, or used indirectly in space cooling, ventilation, and water heating in the building. In the best case scenario, PV panels covering all the roof space available should be able to generate around 250-300MWh. However, this was calculated with the most efficient possible PV efficiencies, the roof was assumed to be flat for convenience of the calculation, and every parts of the roof were assumed to be available for retrieving energy. But in the reality, the roof of the building is round, and not all the parts of the roof may be suitable for PV installation. If the amount of electricity generated does not meet the demand, then more PV systems are possible to be installed on building facades or/and as daylight filters. Conversely, if the amount of electricity generated exceeds the amount of energy required, then the surplus amount of electricity can be sold to the grid or stored.

Later on investigating if we achieved our goal to design zero energy building we could look at energy in the building other way around from generated amount and how it could be used.. That could provide information how many people could be in the building. It is possible to decide afterwards if those conditions are realistic or not.

References 

CIBSE Guide A, 2006, Environmental Design



National Environment Agency, Singapore, Weather statistic <http://app2.nea.gov.sg/weather_statistics.aspx>



World Insolation Map <http://www.oynot.com/solar-insolation-map.html>



Wilson, Robinson, Lumen Method, Acoustics and Lighting (K12ACL), University of



Nottingham, 2012



CIBSE GUIDE, 1998, Energy Efficiency in Buildings, Lighting Design



Design House to Minimize Solar Heat Gain, LSUAgCentre, 2012 <http://www.lsuagcenter.com/en/family_home/home/design_construction/



Safer+Stronger+Smarter/Energy/Design+House+to+Minimize+Solar+Heat+Gain.htm>

1. Twindell, J. and Weir, (1986). Renewable Energy Resources, London E. and F. N. Spain 2. Wong, Yuk Sum (2009). Development of Renewable Energy, ESI Bulletin, Vol.2, Issue 2 < http://esi.nus.edu.sg/docs/esi-bulletins/esi-bulletin-vol-2-issue-2-sept-2009.pdf> 3. Williams, H. H., and R.T. Eubank, (1995) Hydrocarbon Habitat in Rift Basin, Edited by JJ. Lambiase: Geological Society of London Special Publication 4. J.R. Howell, R.B. Bannerot and G.x. Vilet, Solar Thermal Energy Systems Analysis and Design, McGraw Hill, 1985 5. Boyle, G. (2012). Renewable Energy, Power for Sustainable Future, Third Edition. Oxford University Press, Oxford 6. Hussein, W.K.S., (2008) Solar Energy Refrigeration by Liquid-Solid Adsorption Technique, < http://scholar.najah.edu/sites/scholar.najah.edu/files/allthesis/solar_energy_refrigeration_by_liquid-solid_adsorption_technique.pdf> 7. P.N. Cheremisinoff and W.C. Dickinson (Eds.), (1980), Solar Energy Technology Handbook, Marcel Dekker 8. Luque A. and Hegedus S., (2003), Handbook of Photovoltaic Science and Engineering,. John Wiley and Sons 9. Prasad D. Snow M. (2005), Designing with Solar Power: a Sourcebook for Building Integrated Photovoltacis (BiPV), Mugrave, Vic. London. 10. Solar Plaza, (2012), Top 10 World's Most Efficient Solar PV Mono-Crystalline Cells < http://www.solarplaza.com/top10-monocrystalline-cell-efficiency/> 71

11. Product Data Sheet of Sunpower PV Panels <http://us.sunpowercorp.com/cs/BlobServer?blobkey=id&blobwhere=1300271295172& blobheadername2=Content-Disposition&blobheadername1=ContentType&blobheadervalue2=inline%3B+filename%3D11_318_sp_e20_435_ds_en_w_ltr.pdf &blobheadervalue1=application%2Fpdf&blobcol=urldata&blobtable=MungoBlobs> 12. Product Data Sheet of Sanyo Electric PV Panels <http://us.sanyo.com/Dynamic/customPages/docs/solarPower_Solar_Cutsheet_All_HIPxxxBA3_Models-Effective_1_April_2007.pdf> 13. Photovoltaics module image < http://www.solarproductsstore.com/wpcontent/uploads/solar-34.jpg 14. Options for BIPV installations image, from Introduction of Renewable Energy Lecture notes, Lecture 7, Photovoltaics

Appendices Appendix 1

III

Group Report: Building Analysis_Part 1

Articles inside

Figure 46 Photovoltaics modules

Figure 50 Heat gains breakdown aerogel wall

1.2 Building Description

Figure 17 Solar irradiation on April 22nd

2.4 Optimization of Design Variables

2.1.2 Solar Heat Gains

2.8.2 Integration of Renewables In The Built Environment

2.4.6 Walls

Figure 41 Daylight levels for 2nd floor

2.4.12 Internal Heat Gains