Abstract:
This final report enumerates the research design and presents the results and analysis
of the research project carried out under a Senate Research Committee Grant No.
98/01/12.
One of the main contributors to thermal discomfort in tropical buildings is the high
incidence of radiant temperature. The primary reason for the increased radiant
temperature is the heat gain through the roof composite. If the heat gain through the roof
composite could be minimized radiant temperatures inside buildings can be maintained at
or around the comfort levels. Together with adequate air movement, such a radiation
reduction strategy will enhance the comfort levels of tropical buildings.
Insulation plays an important role in controlling heat gain through the roof composite.
Since the intensity of solar radiation and solar altitudes are high in the tropics, buildings
in this region must concentrate more on minimizing heat gain from roof than any other
component of the building envelope.
2. Objectives
The present study aimed at ascertaining the degree of thermal insulation of
conventional and new roofing materials with / without popular roof insulation systems.
The purpose of the exercise was to quantify the reduction in radiant temperature resulting
from the use of roof insulation and to rank them according to empirical data. This data
will be useful for the estimation of thermal comfort effects of various roof insulation
materials which will be studied subsequently.
3. Theory
The solar intensity is defined as the rate at which the Sun's energy is received per unit
of a surface in the absence of the atmosphere by a perfectly absorbing surface at the
mean distance of the earth from the sun and so placed that the radiation falls normally on
it.
If dQ is the quantity of heat received in time dt by a surface having an area of/1, then
the solar intensity /, is given by:
