during summer and winter. Summer means average from 80-85°F while the winter range is from 55-60°F. The in- terior should therefore bear the follow- ing relationship to the exterior:
a)
b)
c)
d)
-
Summer days cooler than out- doors.
-
Summer nights as cool as out- doors
Winter days as warm as or warmer than outdoors Winter nights and mornings much warmer than outdoors. The diurnal range between maxi- mum and minimum of about 6° within one day is considered less important in Hong Kong. The thermal behaviour of most common forms of structure and materials known as the "fly-wheel effect" is most likely to be adequate to compensate this small variation. Radiation
Solar energy is the sole source of power that propels the atmospheric engine which in turn produces the na- tural phenomena of weather and cli- mate. Its heating effect and subsequ- ent heat exchange processes primarily affect our body thermal comfort.
Measurements of total solar and sky radiation received in Hong Kong by the Royal Observatory began in 195811. One salient feature observed is that there is no great seasonal variation in the total amount of direct and sky radiation received, even though there is an annual temperature range of about 30°F.
As air temperature depends on radiation and sunshine hours, this im- plies that re-radiation, both from the sky and surrounding surfaces as well as out-going radiation from the ground, is an important element in the thermal interplay and deserves special atten- tion. Care should be exercised in the choice of structures and building ma- terials, texture and colour, in relation to their thermal behaviour. Humidity
The level of relative humidity is a characteristic of the climate of a place, and is very difficult to control without articificial aid. The inability of the body to evaporate its excess moisture due to continuous high humidity is a feature of the Hong Kong "stuffy" climate.
Hot and humid conditions also foster the growth of fungi and moulds, and cause rapid deteriation and decom- position of many materials. This limits considerably the choice of facing and finishing materials. Emphasis should be laid on providing good ventilation, though this will not necessarily de- crease the amount of humidity.
Wind and air movement
Air movement is an adjunct to thermal comfort in hot weather, but careful control of its movement is necessary during winter if discomfort draughts are to be avoided. In Hong Kong, the emphasis is essentially a
summer one.
An obvious solution lies largely in the planning and orientation of build- ings to receive the prevailing wind, which is mainly easterly except for July which may bring a south-westerly wind. The case of typhoons with hur- ricane winds and gusts of up to 150 m.p.h. is well recognised, as evidenced by the local wind code applicable to all buildings. Rainfall
In Hong Kong, where the principal rainy season is also the hot season and the typhoon season, there is a need to provide the opposite conditions of weathertightness of construction and liberal cross-ventilation indoors. Driv- ing rains during typhoons necessitate a greater degree of protection and place emphasis on window design and construction.
This paper makes a first step to- wards the realisation of an approach to the problem for local conditions. Interpretation and presentation of cli-
Wet Bulb Temp. OF
100
90
во
70
60
60
50
40
50
60
65
75
matic data for design purposes will be the subject of a future article.
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
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Macfarlane, W.V. Thermal Comfort Zones. Architectural Science Review, Vol. 1, No. 1, Sydney, 1958.
Tang, K.H. Design for Climate: An Appraisal of Climatic Influences on Building Design Considerations with Particular Reference to Hong Kong. Far East Architect and Builder, Jan., 1968,
Housing & Home Finance Agency Application of Climatic Data to House Design. Washington, D.C. Jan. 1954. Jackson, Sp. -- The Climatic Environ- ment. Symposium on Design for Tropi- cal Living, C.S.I.R.O. October, 1957. Olgyay, V. Design with Climate: Bioclimatic Approach to Architectural Regionalism. Princeton University
Press, New Jersey, 1963.
van Deventer, E.N. – Some Aspects of Climatological Interpretation with Re- ference to Building Design. C.S.I.R.O. Bulletin 17, Mar. 1959.
Lee, D.H.K.
-
Physiological Objec tives in Hot Weather Housing. U.S. Housing and Home Finance Agency, Washington, D.C. 1953.
Herrington, L.P. Human Factors in Planning for Climate Control. B.R.A.B. Research Conference Report No. 1, Washington, D.C. 1950.
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Kendrick, J.D. Building for Night Comfort in Humid Climates. Far East Architect and Builder, March, 1967. 10. Peacock, J.E. H.K. Meteorological Records and Climatological Notes, 60 Years, Royal Observatory, 1952. 11. Sham, P. Total Solar and Sky Radia- tion in Hong Kong. Royal Observatory, 1964.
80
Effective Temp. Lines
Probable Optimum Comfort Range
(Air❘ movement =
201.p.m.)
70
80
90
100
Dry Bulb Temp. OF
100
90
80
70
60
50
40
30
20
10
કર
Relative Humidity -- %
Fig. 2 Bioclimatic analysis of Hong Kong climate Each dot represents five-day mean values of dry-bulb, wet bulb and relative humidity
Far East BUILDER, November 1968.
35