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1 presentation overview 1 Effect of Courtyard on Thermal Performance of Commercial Buildings in Hot Dry Climate, Ahmedabad, India thesis presentation Rachit Kumar IA/0207 Masters in Interior Architecture and Design, Faculty of Design, CEPT University, Ahmedabad Dec 16, 2009

2 presentation overview 2 introduction literature review background problem description summary methodology and procedure result & analysis annual thermal performance weekly thermal performance research methodology selection of tool building model development alternative variations: parameters of study input parameters and assumptions for models conclusion

3 introduction I background 3 residential, commercial and institutional building sector consumed 31 % of global energy (1990); share is expected to rise to 38 % (2050) [IPCC 1996] % of the total energy demand due to manufacturing materials required in the building sector [IPCC 1996] % total energy demand goes into the running needs of the building [IPCC 1996] World primary Energy Consumption [wikipedia] the growth rate of construction industry in India is 10 % and world average is 5.2% [IGBC 2005] Relative Growth in Energy Consumption ( ) [IPCC 1996]

4 introduction I background 4 India: rural-urban split of (2008) & estimated floor space of 10.5 billion square foot [Source: Maithili Iyer, LBL] HVAC 32% 8% Lighting 60% increase in electricity demand (residential & commercial sectors in India)- 39.7% in as compared to % in as compared to & 37.5% in as compared to consistent increase of about 8% rise in annual energy consumption; building energy consumption increase from 14% in the 1970s to nearly 33% in [Source: UNEP, SBCI & TERI] last decade, a rapid increase in electricity consumption of about 13.2% in the commercial building sector of India [Source: Singh, I., Michaelowa, A. (2004)] Energy Consumption in India by Sectors [Bassi, S., BEE] Agriculture 30.7% Transportation 2.8% Residential 23.4% Commercial 6.6% Industrial 36.5% Energy Consumption in India by Sectors [Bassi, S., BEE]

5 introduction I background commercial buildings consume a large amount of energy in heating, cooling and lighting of the building spaces HVAC 32% Others 8% 5 electricity consumption of typical commercial building in India: 60% of the total electricity for lighting, 32% for space conditioning, and less than 8% for refrigeration [Bassi, S., BEE] Lighting 60% Energy Consumption in the Commercial Buildings [Bassi, S., BEE] 20 to 25 % of the total electricity consumed in government buildings in India is wasted because of inefficient design parameters of buildings [Ministry of Power, India (2000)] need to find effective design measures to lower the energy consumption of buildings and promote more energy-conscious building design Electricity Use in the Commercial Sector in India [Bassi, S., BEE]

6 introduction I energy efficiency & courtyard 6 incorporation of energy efficiency measures in buildings at the design stage; potential of energy savings of 40 50% [IGBC 2005] mechanical conditioning controls can reduce the total mechanical control energy consumption in buildings by up to 47%; if integrated with the other building design variable [1] courtyard a traditional design measure can be used in reducing energy consumption of buildings; cross ventilation, night cooling (radiative cooling-thermal mass), buffer zone, mutual shading, daylighting many researches argue that incorporating courtyards improve the energy efficiency of the buildings [2] thermal performance of courtyard buildings depends on the building configuration factors [2] (scale of success of courtyard building design depends on interaction with surrounding microclimate climate) Thermal behaviour of courtyard building [Source: TERI] Theoretical Source: [1] Mahdavi, A., Effect of Lighting, Zoning, and Control Strategies on Energy Use in Commercial Buildings, Journal of Illuminating Engg Society 24(1) (1995) [2] Aldawoud, A, Comparative analysis of energy performance between courtyard and atrium in buildings, Illinois, Chicago, 2006

7 introduction I problem description 7 the aesthetic and social issues of courtyards are important; consider energy efficiency of the courtyard building understand the relationship of energy consumption, thermal behaviour and various design parameters of courtyard building Energy Efficiency range less consent in terms of energy performance of courtyard building and other design parameters building configurations design parameters the effects of various physical courtyard parameters and thermal performance of courtyard buildings exploring the range of courtyards parameters for energy saving within the limitations of building bylaws and varying buildings configurations urban schemes thermal behaviour Courtyard building

8 introduction I problem description 8 aim: to study the effect of courtyard building configurations on the thermal performance of commercial buildings Research objectives: study the effects of courtyards on the thermal performance of commercial buildings analyze the relationship between energy consumption and design parameters (building height and courtyard form, window percentage and window shading) investigate the effect of various factors on the thermal performance of different building configurations compare the thermal performance of spaces with different orientations and configurations Scope and limitations : study focused on the thermal performance of the courtyard building (It takes into account only the energy consumption due to cooling load (chillers electricity) of the building) study focused on the hot-dry climate of Ahmedabad experimental models are derived from the available urban schemes (site proportions) and building bylaws (setbacks, ground coverage and floor area ratio); new master plans of Indian cities the study is limited to site area of 5000 m2

9 literature review I 9 The literature review is oriented around the following issues: Problems with modern commercial buildings Reasons for incorporating courtyard in buildings Energy performance of courtyard buildings Courtyard shape and size, geometry and proportions and thermal behaviour Courtyard as energy saver for fully mechanical conditioned buildings Experimental studies and computer simulation based studies of courtyard buildings Qualitative studies on courtyard building s thermal performance

10 literature review I summary 10 the courtyard building thermal performance differed from climate to climate the impact of the variables on cooling, heating, and the total annual energy consumption differed with different variables configuration [3] optimum courtyard height to obtain a reasonable performance in summer and winter; three-storey in hot humid climates, two-storey in hot dry and temperate climates, one-storey in a cold climate [4] Sample of investigated courtyard forms Theoretical Source: [3] Aldawoud, A., Thermal performance of courtyard buildings, Illinois Institute of Technology, Chicago, 2006 [4] Ahmed S. Muhaisen, Shading simulation of the courtyard form in different climatic regions, The University of Nottingham, Nottingham, UK, 2005

11 literature review I summary 11 courtyard building exhibits a better energy performance for the low-rise buildings with the increase in building height, the enclosed atrium exhibits a better energy performance [6] Courtyard and atrium building models Theoretical Source: [6] Aldawoud, A., Comparative analysis of energy performance between courtyard and atrium in buildings, Illinois, Chicago, 2007

12 literature review I summary 12 deep courtyard forms with any geometry are suggested to achieve maximum internal shaded areas in summer courtyard geometrical shape has a very small effect on the generated sunlit area in winter; summer the influence is more remarkable [8] Sample of investigated courtyard geometry and forms Courtyard section and plan showing sun path and shaping shading analysis Theoretical Source: [8] Ahmed S. Muhaisen, Mohamed B Gadi, Shading performance of polygonal courtyard forms, The University of Nottingham, Nottingham, UK, 2005

13 literature review I summary 13 the degree to which any of the courtyards encourages warming or cooling during various seasons is greatly dependent on its geometry; each parameter has its own importance [8] Investigated ground proportions and heights of courtyard geometry Type of courtyards Theoretical Source: [8] Rogers, R., An Analysis of Climatic Influences on Courtyard Design for Cold Climates, University of Manitoba, Manitoba, 1999

14 literature review I learning 14 energy performance of courtyard buildings depends upon various parameters best form of courtyard for marginal seasons is not always good from other for annual performance; weekly performance is also important important is to study the performance of various combinations of courtyard parameters rather then to derive best form out of many

15 methodology and procedure I research methodology 15 effects of courtyards on building thermal performance literature study derive simulation cases from variable- plot shape and size, building heights, WWR, space configuration-orientation results analysis conclusion

16 methodology and procedure I research methodology 16 Literature Study Data collection Identifying parameters for study Building Models for simulation Model Development Required parameters Urban scheme - Mohali, India Local building bylaws Building height Building Data-scheduling, occupancy Environment control conditions Construction details Openings parameters Lighting design parameters HVAC design parameters

17 methodology and procedure I research methodology 17 Experiment Computer Simulation Design Builder Input to DB Alternative variations - Output from DB parameters Analysis Output data from DB Annual Thermal Performance Weekly Thermal Performance Plot Shape WWR Shading Floors / Height Vs Energy Consumption Building configuration Adjacent zones Conclusion Comparative analysis

18 methodology and procedure I simulation tool 18 Design Builder Version provides a range of environmental performance data; annual energy consumption, maximum summer temperature, HVAC component sizes etc calculate separate variable of building energy consumption; cooling load, heating load, lighting load and equipment loads Screen shot showing DesignBuilder Modules visualization of site layouts - good 3D interface model data hierarchy - arrangement allows to make settings at building level which can becomes active throughout the whole building; or make settings at block level to change data for all zones/surfaces in the block DesignBuilder models are organized in a hierarchy Screen shot as an example

19 methodology and procedure I building model development 19 Data for Site Site Size = 5000 m2 F.A.R. = 3.5 Front Setback = 15 mts Rear Setbacks = 6 mts Side Setbacks = 6 mts Plot Shape - The square plot and rectangle plot of aspect ratio 1:2 with site area of 5000 m2 each were taken to develop the building models Covering 100 % F.A.R Taking various building heights Taking building of 5 Floors Ground Built-up Area = / 5 = 3500 m 2 > 2920 m 2 (Not applicable) Taking building of 6 Floors building height more than 5 floors is appropriate

20 methodology and procedure I building model development 20 Taking building of 8 Floors Note: Taking 2188 m2 as ground coverage, building models of same areas having courtyard and no courtyard but with same F.A.R. This is applicable to all building heights. Taking building of 10 Floors Taking building of 12 Floors Taking building of 13 Floors For buildings more than 12 floors, floor depth is coming out to be less than 7 mts, which is not an appropriate building depth. Thus, study is restricted to 12 floor building only

21 methodology and procedure I alternative variations 21 Plot Size Square & Rectangle plot Number of Floors / Building Heights Building models of 6 floors, 8 floors, 10 floors and 12 floors Wall to Window Ratios (WWR) Space Configurations Example of 8 floor building model showing 10%, 30%, 60% and 90% WWR N Space with Courtyard Space with Courtyard & all peripheral zones Space with Courtyard & peripheral North zone Space with Courtyard & peripheral South zone Space with Courtyard & peripheral East zone Space with Courtyard & peripheral West zone

22 methodology and procedure I input parameters Building Data Activity Light office work Sector 22 Occupancy 0.2 people/m 2 Metabolic Activity Office Winter Clothing Business suit, thermals, jacket Summer Clothing Trousers & shirts, light business suit Holidays Holidays per year 104 (five working days in a week) Other Gains Computers Heat Gains from computers 10 (W/ m 2 ) Radiant Fraction Office Equipment Heat Gain 16 (W/ m 2 ) Radiant Fraction Environmental Control Heating Setpoint Temperature Heating ( 0 C) 18.0 Heating SetBack( 0 C) 10.0 Cooling Setpoint Temperature Cooling ( 0 C) 24.0 Cooling SetBack( 0 C) 28.0 Humidity Control Humidification Setpoint 10.0 Dehumidification Setpoint 90.0 Minimum Fresh Air Fresh Air 8.00 (l/s- person) Mech Vent per area 1.00 (l/s- m 2 ) Lighting Target Illuminance 300 lux

23 methodology and procedure I input parameters Construction External Walls Walls 20mm plaster/230 brick wall/12 mm plaster, white on both sides Flat roof Internal Partitions 18 mm tile bedding/100 mm brick layer, 125 mm dense cast concert/12 mm plaster 12mm plaster/115 brick wall/12 mm plaster, white on both sides Floors Ground floor 25 mm expended polystyrene, 100 mm brick layer, 100 mm cast concert External floor Internal floor 100 mm dense concert Sub-Surfaces Walls 100 mm concert Internal Roof External door Internal door 100 mm concert 100 mm concert Internal Thermal Mass Construction 100 mm concert Openings 35 mm plywood, painted both side 35 mm plywood, painetd both side External Glazing Glazing type 6mm single clear glass Reveal Layout Dimensions Type Preferred height Varies according to WWR Horizontal strip Window to wall (%) 10%, 30%, 60% and 90% Window height Window spacing Sill height 1500 mm Single horizontal band only 0.75 mm No 23

24 methodology and procedure I input parameters Dividers Type Divided lite Width Horizontal and Vertical dividers 1 Projection 20 mm No Glass edge centre conduction 1.00 Frames Frame width 40 mm Frame inside and outside projection No Glass edge centre conduction 1.00 Shading Local shading Overhangs Details 900 mm long concert projection Lighting General Lighting Lighting Energy 4.00 W/m lux Task and Display Lighting HVAC System Type Laminar Type Radian Fraction 0.72 Visible Fraction 0.18 Surface mounted Off Dual-Duct VAV 24 Mechanical ventilation Outside air definition method By zone or minimum fresh air per person Fans Fan type Office Pressure rise (Pa) 700 Total efficiency (%) 70 Fan in air (%) 100 Cooling Chiller CoP 0.76 Cooling Distribution Loss 5%

25 methodology and procedure I simulation cases Square Plot Rectangle Plot 25 2 Plot Sizes 6 Floors Building 8 Floor Building 10 Floor Building 12 Floor Building 4 Building Heights Space without Courtyard Space with Courtyard* Space with Courtyard having peripheral Zones Space with Courtyard having East peripheral Zone Space with Courtyard having West peripheral Zone Space with Courtyard having North peripheral Zone Space with Courtyard having South peripheral Zone 7 Space Configurations WWR 10 % WWR 30 % WWR 60 % WWR 90 % 4 WWR Shading No Shading * Note: 6 Floor Building models do not have Space with Courtyard Total Simulation Cases = [2 Plot Size X 4 Heights X 7 Configurations X 4 WWR X 2 Shadings] [2 Plot Size X 1 Height (6 only) X 1 Configurations (Space with courtyard) X 4 WWR X 2 Shadings] = = Window Shading

26 methodology and procedure I simulation cases 26 Square Plot 6 Floor Building 8 Floor Building 10 Floor Building 12 Floor Building No Courtyard Courtyard Courtyard with Zones 10 % WWR 30 % WWR 60 % WWR 90 % WWR No Shading Shading Courtyards with East Zone Courtyards with West Zone Courtyards with North Zone Courtyards with South Zone Rectangle Plot 6 Floor Building 8 Floor Building 10 Floor Building 12 Floor Building Courtyard with Zones Courtyard No Courtyard 10 % WWR 30 % WWR 60 % WWR 90 % WWR No Shading Shading Courtyards with East Zone Courtyards with West Zone Courtyards with North Zone Courtyards with South Zone

27 Energy Consumption analysis 27 Annual Thermal Performance Weekly Thermal Performance Floors / Height Vs Energy Consumption Floors / Height Building Configuration Adjacent zones (E, W, N, S) Building shape (plot shape) WWR Shading

28 analysis I annual thermal performance I building configurations 28 Floor 6 Floor 8 Floor 10 Floor 12 Space NO Courtyard Space with Courtyard Space with Courtyard-Zones Electricity (kwhr)/m2 Percentage % Electricity (kwhr)/m2 Percentage % Electricity (kwhr)/m2 Percentage % Electricity (kwhr)/m2 Percentage % Table 1: Square building with 30% WWR Space NO Courtyard Space with Courtyard Space with Courtyard-Zones Floor 6 Floor 8 Floor 10 Floor 12 Electricity (kwhr)/m2 Percentage % Electricity (kwhr)/m2 Percentage % Electricity (kwhr)/m2 Percentage % Electricity (kwhr)/m2 Percentage % Table 2: Square building with 90% WWR courtyard adjacent zones thermal load reduced w.r.t to building with courtyard by % for 8 floors, 3.95% for 10 floors and 7.69% for 12 floors building energy consumption of courtyard adjacent space (zones) reduces with the increase in building height in comparison with building with courtyard

29 analysis I annual thermal performance I building configurations 29 Graph 1: Square Building with Different WWR and No Shading: Comparison between Different Building Configurations difference in energy consumption of building with courtyard and building with courtyard zones increase with height and WWR the presence of courtyard help in increasing the thermal performance of buildings (referred to 6 floor building model)

30 analysis I annual thermal performance I building configurations 30 Graph 2 & 3: Square Building with 30% & 90% WWRs and different Configurations: Comparison between Shading and No Shading performance of the Building Configurations reduction in thermal load for 8 floor building of space with courtyard and space with courtyard zones is 11% and 14% for 30 WWR & reduction of 11% and 15% for 90 WWR increase in thermal load with increase in WWR; effectiveness of shading increases no effect of shading with alterations in height

31 analysis I annual thermal performance I building configurations 31 Graph 4 & 5: Square & Rectangle Building with 30% & 90% WWRs and different Configurations: Comparison between shape of the Building Configurations thermal load of building with no courtyard and building with courtyard; less impact with change in shape of the building increment in thermal load due to increase in WWR

32 analysis I annual thermal performance I courtyard adjacent zones 32 Graph 6: Square Building with Different WWR and No Shading: Comparison between Different Courtyard Zones increase in height of building; less effect on the thermal load of the building increase in WWR; thermal load shifts in constant pattern thermal energy consumption of east zone is high for all the WWR

33 analysis I annual thermal performance I courtyard adjacent zones 33 Floor 6 Floor 8 Floor 10 Floor 12 Floor 6 Floor 8 Floor 10 Floor 12 Electricity (kwhr)/m2 Electricity (kwhr)/m2 Electricity (kwhr)/m2 Electricity (kwhr)/m2 Electricity (kwhr)/m2 Electricity (kwhr)/m2 Electricity (kwhr)/m2 Electricity (kwhr)/m2 East Zone West Zone North Zone South Zone Table 1: Square building with 30% WWR East Zone West Zone North Zone South Zone Table 1: Square building with 90% WWR

34 analysis I annual thermal performance I courtyard adjacent zones 34 Graph 7 & 8: Square Building with 30% & 90% WWRs and different Courtyard Zones: Comparison between Shading and No Shading performance of the Building Configurations north zones; small variation for all the WWR east zone and south zone; maximum shading affect for all WWRs east zones; 14% reduction in thermal load for 30% & 90% WWR and south zone shows a decrement of thermal load by 19% for 30% WWR

35 analysis I weekly thermal performance I building configurations 35 Graph 9 & 10: Square Building with different WWRs and no shading: Comparison between weekly thermal performances of different building configurations thermal load for typical winter week varies from 4-12 KWhr/m2; typical summer week varies from KWhr/m2 increase in WWRs; critical for summers weekly thermal load decreases with decreases in height for building with no courtyard and building with courtyard for all WWRs less variation in thermal load for courtyard adjacent zones

36 analysis I weekly thermal performance I courtyard adjacent zones 36 Graph 11 & 12: Square Building with different WWRs and no shading: Comparison between weekly thermal performances of different building configurations variations in thermal load in summer week; constant for all WWRs; 90% WWR large deviation within different zones small variation in winter week for all zones except for north zone

37 conclusions I inferences 37 low rise buildings are more energy efficient (thermal load of the building increases with the increase in height of the building; due to increased ability of solar radiations to enter the courtyard with the increase in depth of the courtyard forms; depth of courtyard increases with the increase in height to maintain 100% F.A.R.) less effect of the courtyard form (square & rectangle) on the thermal performance of the building with different parameters east zone is most critical zone (huge amount of heat gets trapped within the building during nigh hours and thus can lead to high thermal building load) effectiveness of shading is best resulted for south zones and east zones efficiency of shading increases with the increase in WWRs building with courtyard consumes more energy than building with no courtyard (large courtyard area results in high sun exposure and huge heat gain)

38 conclusions I 38 the thermal performance of the courtyard buildings depends upon the ratio of courtyard size to adjacent building size the importance of each geometric parameter varies from one form to the another changes in courtyard geometry need not necessarily be architecturally significant to affect courtyard thermal conditions of the building determining the relative qualities of one configuration versus another for specific proportions is difficult introducing a courtyard in a building is not always an acceptable solution unless it s all the parameters are not proficiently used

39 conclusions I future recommendations 39 area of the courtyard is a significant factor to study Figure 5: shows different courtyard area various building cluster patterns of commercial buildings (thermal performance can be improved by allowing air movement over the skins of building mass; depends on design of particular building envelope as well as urban planning schemes; urban policies can play a role in improving the energy consumption of the buildings) Figure 6: different land use schemes; adjoining courtyard buildings, single building mass and building in rows different courtyard types and its relevance to different climatic zones