Thursday, May 29, 2008

Tropical Design Module 5: Climatic Zones for Bldgs


Comfort Zone
The range of conditions under which most people feel comfortable. It is a function of a number of variables

Thermal Comfort
Human comfort as determined by the ability of the body to dissipate the heat and moisture it produces by metabolic action.

Relationship between the centre of the comfort zone and the annual mean temperature (Carl Mahoney):
Tcc = Tam/4 + 17.2
where Tcc is the center of the comfort zone in E.T. oC
and Tam is the annual mean temperature
*Always correct to the nearest 0.5 upwards

To get the Tam (annual mean temperature):
Tam = (Highest DBT of the Year + Lowest DBT of the Year) / 2
Psychrometric Chart
A chart relating the wet-bulb and dry-bulb readings from a psychrometer to relative humidity, absolute humidity and dew point


The comfort zone criteria given above are for sedentary activities:
discomfort due to slight sweating in sedentary activities may be more uncomfortable and disturbing as it interrupts concentration.

The comfort zone is compared with the mean maxima (day) and minima (night) effective temperature for each month to find out if the climate is comfortable or uncomfortable.

Recommendations to achieve comfort can be made for a great number of aspects from space between buildings, building form, down to detail aspects of design.
§ consider window size together with other factors such as glazed area, orientation, shading and building form consider thermal characteristic of roofs and walls, i.e., absorption of the surface and the insulation of the construction.

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