department of architecture the university of hong kong building design for cold climates sam c m...

Department of ArchitectureThe University of Hong Kong

Building Design forCold Climates

Sam C M Hui, Mar 2001

Contents

Climate Basics

Cold Climates

Response to Climate

Human Factors

Climatic zones in the world

Cold climates Temperate climates

Hot-dry climates Warm-humid climates

Climate Classifications

Climate Basics

Cold climates lack of heat (under-heating)

Temperature climates seasonal variation between under-heating and

over-heatingHot-dry (arid) climates

overheating, dryWarm-humid climates

overheating, humid

Climate Basics

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

Major climatic elements of Hong Kong

Cold Climates

Polar climates require special attentionAssume 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)

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.

Cold climate (example)

- protection from wind, cold, snow drift and snow load- design for minimum heat loss

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

Tokyo, January 1998

How could I respondto cold climate?

* Face House, Kyoto, Japan

Main criteria:• built form • orientations• wall area• window area• thermal insulation• thermal mass

Response to Climate

Climate-responsive building (Tokyo Gas Earth Port, Japan)

General climate control strategies

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

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

Response to Climate

Selection and design of window system

Activesolar

Passivesolar

{

}

Effective use of solar energy

Human Factors

Solar heatand radiation

Wind chill

Heat conductionand convection

Evaporativeheat loss

Human Factors

ASHRAE comfort envelopeThermal comfort &design conditions

Asymmetricthermal radiation

Warm orcold floor

Draft

Vertical airtemp. diff.

Local thermal discomfort

Draft - undesired localcooling of human bodycaused by air movement

Asymmetric thermal radiation in a space

Vertical air temperaturedifference - the temperaturegradient may cause localwarm discomfort at the headand/or cold discomfort at thefeet

Warm or cold floor -direct contact between thefeet and the floor causesdiscomfort; flooringmaterial is important toavoid this problem

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

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]

Further questions:

Web: http://arch.hku.hk/research/BEER

Email: cmhui@hku.hk