Air Conditioning, Comfort and Energy in India s Commercial Building Sector

Transcription

1 Air Conditioning, Comfort and Energy in India s Commercial Building Sector THINK.CHANGE.DO Leena Thomas Richard dedear Rajan Rawal Ashok Lall PC Thomas University of Technology, Sydney Sydney University CEPT University Ahmedabad Ashok B Lall Architects Team Catalyst

2 Context - India 80 % of the India of 2030 is yet to be built! (McKinsey and Co 2009)

3 Context - India Unprecedented rate of urbanisation Buildings account for 47% of final energy use (IEA 2007) Air conditioning accounts for 50% of energy use in commercial buildings (TERI 2005)

4 New Delhi % increase in population population 25,000,000 20,000,000 15,000,000 10,000,000 population Source: Delhi Development Authority Perspective Plan ,000,

5 New Delhi % increase in power demand power infrastructure demand MW Source: Delhi Development Authority Perspective Plan availability 2021-projected requirement

6 A Climate Rejecting Approach to Architecture Clean unshaded facades Extensive use of glass

7 A Climate Rejecting Approach to Architecture Clean unshaded facades Extensive use of glass Sealed windows Deep floor plate Energy Intensive

8 A Climate Rejecting Approach to Architecture Clean unshaded facades Extensive use of glass Sealed windows Deep floor plate Energy Intensive

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10 Preference for glass to be in line with the latest trends in the architecture as well as the market requirements for contemporary looking structures DLF flyer 2004

11 Standards for Thermal Comfort in India No real standard for thermal comfort in India National Building Code - design conditions for Air conditioned buildings deg C in summer deg C in winter For naturally ventilated buildings focuses on design strategies for air flow nominates a Tropical Summer Index range; 27.5 deg C as optimum

12 Standards for Thermal Comfort in India No real standard for thermal comfort in India Energy Conservation Building Code for air conditioned buildings No recommended temperature and humidity conditions for naturally ventilated buildings Refers to the dedear Brager adaptive comfort model (ASHRAE 55-R) as additional information ECBC acknowledges need for regional Thermal Comfort guidelines as the next step

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14 The cost of a technocentric view of comfort

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16 The cost of a technocentric view of comfort Universally standardised conditions

17 The cost of a technocentric view of comfort Universally standardised conditions eg ± 1.0 degree Centigrade mandates air-conditioning as the first option

18 Investigating an alternate approach Post occupancy evaluation studies Transport Corporation of India Torrent Research Centre New Delhi Ahmedabad Thomas 2006, Thomas and Baird, 2006, Thomas in Baird 2010

19 TCI - Low Energy Strategies Minimise solar gain External window to wall ratio 18% Highlight windows to enhance daylight ingress Central Light Well Landscape as an environmental filter 100% fresh air cycle when ambient conditions permit Night cooling of thermal mass Air conditioned - diesel fired absorption chillers Thermostat settings 24 ± 1ºC in summer allowing space temperatures to ride over 26 degrees

20 TCI BUS summary chart 94 respondents Temperature in summer: overall Temperature in winter: overall Temperature in monsoon: overall Air in summer: overall Air in winter: overall Air in monsoon: overall Lighting: overall Noise: overall Comfort: overall Design Needs Health (perceived) Image to Visitors Productivity (perceived) homas 2006

21 Torrent Research Centre - Low Energy Strategies Passive Downdraft Evaporative Cooling Limited glazing and recessed windows Diffused daylight to central walkways Daylit labs and offices Ceiling fans Night Cooling Overt expression of thermal control system Threshold temperature at 28 o C

22 L.Thomas and Baird 2006, Thomas 2010 Overall Comfort Temperature and Air Summer Performance in PDEC Designed for a threshold 28 deg C for ~ 98% hours In reality Internal temperatures were sucessfully maintained degrees below peak 5 degrees lower than average external temperatures internal temperatures of 29-30ºC achieved when outside temperatures reach 43-44ºC. (Baird 2001, Majumdar 2001b, Ford 1999) Ceiling fans introduced after first year

23 L.Thomas and Baird 2006, Thomas Building Use Studies Torrent PDEC BUS summary chart 100 respondents Temperature in summer: overall Temperature in winter: overall Temperature in monsoon: overall Air in summer: overall Air in winter: overall Air in monsoon: overall Lighting: overall Noise: overall Comfort: overall Design Needs Health (perceived) Image to Visitors Productivity (perceived)

24 Universally standardised comfort criteria

25 Adaptive comfort

26 DECEMBE NEW

27 Ask the Occupant Temperature: Neutral (neither hot nor cold) Acceptable No change Comfort Overall rated at 5 out of 7 Suggests : I m comfortable

28 Physical Measures Temperature 25.6 o C Relative Humidity 37.3% Air Speed 0.01m/s Globe Temperature 25.3 o C Based on comfort norms : THOU ART TOO HOT!

29 The next stage. A detailed study of Comfort People and Technology A multi-methodological post occupancy evaluation of 15 buildings and its occupants in 3 climate zones Different comfort regimes and environmental control regimes TOWARDS an alternate comfort model that is specific Indian cultural social and climatic context

30 Climate zones Account for more than the vast majority of India s urban development: Warm humid Composite Hot dry

31 Building environmental control systems 1. Naturally ventilated with no/minimal active heating or cooling systems Includes ceiling fans CEE Ahmedabad Centre for Development Studies Trivandrum

32 Building environmental control systems 2. Old style mixedmode buildings. Naturally ventilated buildings with supplementary airconditioning to manage discomfort in extreme weather conditions. Office buildings Ahmedabad

33 Building environmental control systems 3. Mixed mode green buildings. Includes - high-performance contemporary office buildings - advanced natural ventilation systems Sehgal Foundation: Institute for Rural Research and Development

34 Building environmental control systems 3. Mixed mode green buildings. Includes - high-performance contemporary office buildings - advanced natural ventilation systems Torrent Research Centre Ahmedabad

35 Building environmental control systems 4. Grade-A air conditioned office buildings. Need a named example -

36 Building environmental control systems 5. Energy efficient air-conditioned buildings Spectral Headquarters Transport Corporation of India

37 A multimethodological approach Building design and configuration site visits, documentation Operational energy consumption related to the provision of comfort - Site Visit and Walk through energy audit Logging of concurrent outdoor weather conditions onsite and met data

38 A multimethodological approach Overall occupant experience of the building, as designed and operated BUS survey Workplace thermal comfort - de facto protocol for ASHRAE 55 R(de Dear and Brager, 1998). - comfort survey, coincident physical measurement, and documentation of clothing and activity regimes

39 Project ambitions and outcomes Identify optimum approach for comfortable low energy intensive buildings Validate the adaptive relationship between subjective thermal comfort indoors and the outdoor climatic conditions

40 Project ambitions and outcomes Establish a database of occupant comfort, thermal performance and energy consumption observations Develop a comfort-energy index Regionalise the adaptive comfort model

41 Project ambitions and outcomes generate substantive savings in energy costs and greenhouse gas emissions. support India s transition to a low-carbon economy