Orientation of roof and openings: their influence on indoor thermal comofrt of single-storey houses

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.