Abstract:
At present, the selection of the roof type and roof orientation for houses is
primarily based on cost and aesthetic considerations, without much regard to the thermal
performance of the roof. However, since Sri Lanka is a tropical country, the roof causes
significant adverse effects on the thermal comfort indoors and therefore its thermal
performance should be carefully considered on selection of the roof type and orientation.
Otherwise the resulting warm indoors will cause the occupants to use fans. This is not a
healthy development due to the energy crisis the country is now facing. Another aspect that
deserves attention is the orientation of openings.
This paper investigates the effect of the orientation of the roof and the openings on the indoor
thermal comfort of single storey houses. Two roof types commonly adopted in Sri Lanka are
considered, namely cement fibre roof with cement fibre flat ceiling and cement fibre roof
with sloping cement fibre ceiling. Using DEROB-LTH computer program, a four-room
model house was simulated. For two roof orientations, i.e. the ridge along east-west and the
ridge along north-south, the simulations were carried out for March, June and December,
when different extremes of sun path occur. The results indicate that the roof orientation is
not so significant as the orientation of openings on the indoor thermal comfort in single
storey houses.
