Department of Architecture The University of Hong Kong

1. Department of ArchitectureThe University of Hong Kong Building Design for Cold Climates Sam C M Hui, Mar 2001

2. Contents • Climate Basics • Cold Climates • Response to Climate • Human Factors

3. Climatic zones in the world

4. Climate Classifications Cold climates Temperate climates Hot-dry climates Warm-humid climates

5. Climate Basics • Cold climates • lack of heat (under-heating) • Temperature climates • seasonal variation between under-heating and over-heating • Hot-dry (arid) climates • overheating, dry • Warm-humid climates • overheating, humid

6. Climate Basics • Climatic elements • Temperature • Humidity • Air movement (wind speed and direction) • Precipitation (rain, hail, snow, dew) • Cloud cover • Sunshine duration • Solar radiation

7. Major climatic elements of Hong Kong

8. Cold Climates • Polar climates require special attention • Assume temperate climates • e.g. Canada, UK, New Zealand, Northern China • Severe winters, with snow and strong icy winds • Major considerations • Max. summer temperatures • Min. winter temperatures • Annual rainfall and humidity (dry or wet) • Sky conditions (cloudy or clear)

9. Cold Climates • Design principles • Minimal surface-to-volume ratio • Insulation of all external surfaces is very important • Small windows and openings, preferably double-glazed • Annual solar gains through windows are generally less that associated heat losses • Use of exposed internal thermal mass • Lightweight insulated structures are quick to heat up but also quick to cool, • Heavyweight structures are slow to heat up and cool down.

10. Cold climate (example) - protection from wind, cold, snow drift and snow load - design for minimum heat loss

11. Temperature climate (example) • protection from rain, snow, cold winds, moderate summer • heat & moderate winter cold • minimize heat loss, maximize isolation in winter; consider • summer shading and ventilation

12. Tokyo, January 1998

13. How could I respond to cold climate? • Main criteria: • built form • orientations • wall area • window area • thermal insulation • thermal mass * Face House, Kyoto, Japan

14. Response to Climate Climate-responsive building (Tokyo Gas Earth Port, Japan)

15. General climate control strategies

16. Response to Climate • Building envelope - outer shell of a building that determines external thermal forces • exterior walls • exterior windows • roofs • underground slab and foundation • doors open to outdoor

17. Response to Climate • Major factors determining envelope heat flow: • temperature differential, T • area of exposed building surfaces, A • heat transmission properties, like U-value • thermal storage capacity • Effect of thermal mass • delay heat transfer and store heat • important for intermittently heated spaces

18. Response to Climate Selection and design of window system

19. Effective use of solar energy } Active solar Passive solar {

21. Human Factors Heat conduction and convection Solar heat and radiation Evaporative heat loss Wind chill

22. Human Factors Thermal comfort & design conditions ASHRAE comfort envelope

23. Local thermal discomfort Asymmetric thermal radiation Draft Vertical air temp. diff. Warm or cold floor

24. Draft - undesired local cooling of human body caused by air movement

25. Asymmetric thermal radiation in a space

26. Vertical air temperature difference - the temperature gradient may cause local warm discomfort at the head and/or cold discomfort at the feet

27. Warm or cold floor - direct contact between the feet and the floor causes discomfort; flooring material is important to avoid this problem

28. References • Climatic Design of Buildings - An Overview • http://arch.hku.hk/~cmhui/teach/65156-7.htm • Climatic Design • http://fridge.arch.uwa.edu.au/topics/thermal/climate/design.html • Climate Classification • http://fridge.arch.uwa.edu.au/topics/thermal/climate/classification.html

29. References • Hutcheon, N. B. and Handegord, G. O.P., 1983. Building Science for a Cold Climate, National Research Council of Canada, Toronto. [690.0911 H9] • Lstiburek, J. W., 2000. Builder’s Guide to Cold Climates: Details for Design and Construction, Taunton Press, Newtown, Conn. [693.8 L925 b] • Markus, T. A. and Morris, E. N., 1980. Buildings, Climate, and Energy, Pitman, London. [697 M34] • Watson, D. and Lab, K., 1983. Climatic Design: Energy-efficient Building Principles and Practices, McGraw-Hill, New York, 1983. [697.9 W3]

30. Further questions: Web: http://arch.hku.hk/research/BEER Email: cmhui@hku.hk