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

2. Contents zClimate Basics zCold Climates zResponse to Climate zHuman Factors

3. Climatic zones in the world

4. Cold climatesTemperate climates Hot-dry climatesWarm-humid climates Climate Classifications

5. Climate Basics zCold climates ylack of heat (under-heating) zTemperature climates yseasonal variation between under-heating and over-heating zHot-dry (arid) climates yoverheating, dry zWarm-humid climates yoverheating, humid

6. Climate Basics zClimatic elements yTemperature yHumidity yAir movement (wind speed and direction) yPrecipitation (rain, hail, snow, dew) yCloud cover ySunshine duration ySolar radiation

7. Major climatic elements of Hong Kong

8. Cold Climates zPolar climates require special attention zAssume temperate climates ye.g. Canada, UK, New Zealand, Northern China ySevere winters, with snow and strong icy winds zMajor considerations yMax. summer temperatures yMin. winter temperatures yAnnual rainfall and humidity (dry or wet) ySky conditions (cloudy or clear)

9. Cold Climates zDesign principles yMinimal surface-to-volume ratio yInsulation of all external surfaces is very important ySmall windows and openings, preferably double-glazed yAnnual solar gains through windows are generally less that associated heat losses yUse of exposed internal thermal mass yLightweight insulated structures are quick to heat up but also quick to cool, yHeavyweight 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? * Face House, Kyoto, Japan Main criteria: built form orientations wall area window area thermal insulation thermal mass

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

15. General climate control strategies

16. Response to Climate zBuilding envelope - outer shell of a building that determines external thermal forces yexterior walls yexterior windows yroofs yunderground slab and foundation ydoors open to outdoor

17. Response to Climate zMajor factors determining envelope heat flow: ytemperature differential,  T yarea of exposed building surfaces, A yheat transmission properties, like U-value ythermal storage capacity zEffect of thermal mass ydelay heat transfer and store heat yimportant for intermittently heated spaces

18. Response to Climate Selection and design of window system

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

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

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

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

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 zClimatic Design of Buildings - An Overview yhttp://arch.hku.hk/~cmhui/teach/65156-7.htm zClimatic Design yhttp://fridge.arch.uwa.edu.au/topics/thermal/clima te/design.html zClimate Classification yhttp://fridge.arch.uwa.edu.au/topics/thermal/clima te/classification.html

29. References yHutcheon, N. B. and Handegord, G. O.P., 1983. Building Science for a Cold Climate, National Research Council of Canada, Toronto. [690.0911 H9] yLstiburek, J. W., 2000. Builder’s Guide to Cold Climates: Details for Design and Construction, Taunton Press, Newtown, Conn. [693.8 L925 b] yMarkus, T. A. and Morris, E. N., 1980. Buildings, Climate, and Energy, Pitman, London. [697 M34] yWatson, 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