1. Arch6026 - Building Systems II (2000/2001) Energy and Environmental Systems for Green Buildings Lecture 04 - Efficient Use of Energy in Buildings

2. Contents zEnergy Use in Buildings zDesign Factors zDesign Strategies

3. Energy Use in Buildings zEnergy (or heat) unit: y1 kWh = 3.6 MJ = 860 kcal = 3412 Btu zPower unit: y1 W = 1 J/s = 0.86 kcal/h = 3.41 Btu/h zForms of energy xelectricity, town gas/LPG, oil/coal products zEnergy end-use xHVAC, lighting, equipment, hot water, and processes

4. Energy end-use in Hong Kong by sectors, 1984-97

5. Energy Use in Buildings zBuildings (comm. + resid.) is an important energy consumer (30-50% of total) yenergy consumption patterns xaffected by building functions, occupant behaviour, climate, and building design yenergy saving potential is often large ygoal of energy efficiency xoptimise energy performance w/o compromising the human comfort and well-being

6. Energy consumption patterns in commercial buildings (Data source: Energy Efficiency Office, HK)

7. Energy consumption patterns in commercial buildings (cont’d) (Data source: Energy Efficiency Office, HK)

8. Energy consumption patterns in residential buildings (Data source: Energy Efficiency Office, HK)

9. Energy Use in Buildings zEnergy and environment (global) yenergy/electricity generation xgreenhouse gas emission xcause global warming and climate change yCO 2 emissions factors xelectricity = 0.832 kg/kWh x(natural) gas = 0.198 kg/kWh xcoal = 0.331 kg/kWh

10. Key factors influencing energy consumption

11. Major Factors zMajor design factors: yclimate and site ybuilding envelope and form ybuilding services systems yhuman factors zEnergy design guidance (see notes) ydesign guidelines ychecklist for energy efficiency in buildings ysketch design (from CIBSE Guide)

12. Major Factors zClimate and site yclimate xtemperatures, humidity, solar radiation, wind data xaffect thermal performance, daylighting, solar energy utilisation, and ventilation ysite xtopography, vegetation, built forms, water xin harmony with the environment and make effective use of local conditions

13. Major climatic elements of Hong Kong

14. Wind Water Light Matter Major site factors

15. Major Factors zBuilding envelope ywalls, roofs, windows, skylights, etc. xthermal properties, e.g. U-value yconsiderations xclimate excluding or climate responsive? xuse building fabric for thermal storage? xthermally heavyweight or lightweight? xdeep or shallow plan? xhighly glazed or little glazing? xneed for solar control?

16. Look at me. Is my face (building envelope) energy efficient? * Face House, Kyoto, Japan Main criteria: wall area window area thermal properties orientations thermal mass shading device

17. Properties of window glasses

18. Major Factors zBuilding services systems yHVAC systems ylighting systems yelectrical services systems ylifts and escalators ywater supply systems ytown gas supply system

19. Thermal energy balance in a building space

20. Design Strategies zProcess of energy efficient design yidentify user requirements ymeet the requirements with minimal energy use yestablish energy efficient brief & design team yset up energy targets ydesign efficient, maintainable & flexible systems ycheck the final design meets the targets

21. Design Strategies zMinimise energy requirements yoptimise internal heat gains yoptimise natural ventilation ydesign for & use daylighting ybetter use of fabric thermal storage yheat recovery y‘free’ cooling yminimise distribution losses

22. Design Strategies zThermal yventilation strategies ycooling strategies yheating strategies zLight ylighting strategies ydaylighting strategies zServices strategies

23. Good design practices Good house- keeping Efficient systems Efficient operation User education & awareness Interdisciplinary team approach

24. Design Strategies zImportant things to do ydevelop a better understanding of energy efficient technologies and methods yacquire the techniques and skills for building energy analysis yevaluate the energy performance of different design options in your projects yexamine the energy design and green building issues in context