Building energy simulation in practice Seminar of the CIBSE Building Simulation Group 30th September 2009

Transcription

1 Building energy simulation in practice Seminar of the CIBSE Building Simulation Group 30th September 2009 Sustainable design of lower carbon buildings in a changing climate EngD in Environmental Technology David Williams CEng MEng MCIBSE MIMechE

2 Overview Limited perspective of regulated building energy analysis Life cycle thinking applied to construction Influence of climate change on energy demand and comfort

3 Regulatory requirements

4 Regulatory requirements Fabric Improvements System Improvements Cooling Heating Lighting Domestic Hot Water Operational System Boundary Fans, Pumps and Controls Total Annual CO 2 Emission

5 Life cycle perspective Energy and Resources Raw material acquisition Upstream material flows Processing Transportation Construction Cumulative emissions Operation Time Demolition Waste and Emissions Waste Management Downstream material flows

6 Life cycle perspective How significant are these additional flows to building design? Does regulation deal with these issues in other ways? Material Flow Upstream material flows System Boundary What is the extent of the system boundary? What impacts on the environment should be considered? Operational Boundary Operational Lifetime Time Downstream material flows

7 How significant are other material flows? Life cycle perspective A 1996 study showed an office s operational phase represented 80-90% of all primary energy demand However this could be reduced by 50% by including low energy features (Cole and Kernan, 1996) Raw material acquisition Processing Transportation In a 2002 study embodied energy represented 67% of the operation phase (Yohanis and Norton, 2002) Construction Operation 2016 Zero carbon homes 2019 Zero carbon non-domestic buildings Demolition Waste Management

8 Life cycle perspective How are material flows currently regulated? BREEAM BRE Green Guide / Environmental Profiles Site Waste Management Plans Invest2 Software No cohesive tool to think of material flows in the same way as operational demands What environmental impacts should we consider? Extraction of resources Water use Acidification Raw material acquisition Processing Transportation Construction Operation Photo-oxidant Formation Ozone Depletion Human-toxicity Demolition Climate change Eco-toxicity Eutrophication Waste Management

9 Life cycle perspective CO 2 CH 4 GWP N 2 O CO 2 e SF 6 HFC s PFC s Climate change

10 Life cycle perspective Protecting the environment from us or protecting us from the environment? Raw material acquisition Processing Material Flow Transportation Construction (Mitigation) Operation Operational Boundary Operational Lifetime Demolition Waste Management Climate change Climate change (Adaptation)

11 Life cycle perspective Adaptation to climate change 10% probability level. Very unlikely to be less than 50% probability level. Central estimate 90% probability level. Very unlikely to be greater than CIBSE TM48: Use of climate change scenarios for building simulation Using UKCIP02 data Change in mean temperature / C UK Climate Impacts Programme, 2009

12 Life cycle perspective 1. We must build an understanding of the wider life cycle impacts on climate change caused by construction Is zero carbon really life cycle optimised? Should we replace existing air conditioned buildings with new naturally ventilated alternatives? 2. We must understand how buildings will respond to climate change over their lifetimes How will zero carbon buildings perform in the future? Will they still be zero carbon?

13 Design for Climate Change

14 CIBSE Test Reference Year Weather Sites Dry Bulb Temperature Wet Bulb Temperature Wind Speed Wind Direction Global Horizontal Irradiation Global Diffuse Radiation Atmospheric Pressure Cloud Cover

15 Thanet College Project

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17 Met Office Weather Data

18 Missing Data

19 Missing Data

20 Building a Test Reference Year

21 Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Jan Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr Apr May May May May May May May May May May May May May May May May May May May May Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jun Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Jul Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Aug Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Sep Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Oct Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec Creating Dec balanced Dec Dec environments Dec Dec Dec

22 Cumulative Distribution Function Frequency Temperature / C '20 Year' PDF Cumulative frequency Temperature / C '20 Year' CDF

23 Cumulative Distribution Function FS( p, m, y) = N i= 1 CDF( p, m, y, i) CDF( p, N y, m, i) FS sum = w1 FS( DryT ) + w2fs( GlRad) + w3fs( Wind)

24 Assembling the Test Reference Year Month Adopted Year Month Adopted Year January 1994 July 1996 February 1999 August 1989 March 1999 September 1995 April 2005 October 1996 May 1997 November 1992 June 1996 December 2004

25 Historical Climate Trends

26 Historical Climate Trends

27 Future Climate Trends

28 Climate Scenarios

29 Climate Modelling HadCM3 HadRM3

30 UK Climate Impacts Programme TEMP m Mean Temperature / C TMAX m Maximum Temperature / C TMIN m Minimum Temperature / C SPHU m Specific Humidity / g/kg WIND m 10m Wind Speed / m/s DSWF m Total Downward Surface Shortwave Flux / W/m² TCLW m Total Cloud in Longwave Radiation / % MSLP m Mean Sea Level Pressure / hpa

31 Data Shift Atmospheric Pressure Cloud Cover

32 Data Stretch Global and Diffuse Solar Radiation Humidity Wind Speed

33 Data Shift and Stretch Dry Bulb Temperature

34 Future Predictions Heating Degree Days Mean Temp Cooling Degree Hours

35 Test Model

36 Thanet College 3.8m 2.6m 8.0m 1.3m 1.3m 6.5m

37 Thanet College People Lighting Computers & Equipment

38 Overheating Results DSY % Threshold

39 Energy Demand Heat generation efficiency 92.00% Heat delivery efficiency 93.92% Total heating system efficiency 86.41% Cooling generation efficiency 300% Cooling delivery efficiency 99% Heat rejection fan and pump power 10% Total cooling system efficiency 212% Boiler Energy Chiller Energy

40 CO 2 Emission

41 Conclusions Cooling demand dominates over longer life spans Overheating risk is of concern Reference to UKCIP 2009 data is needed Requirement for move to life cycle thinking

42 Sustainable design of lower carbon buildings in a changing climate