Performance of roof and ceiling systems in tropical thermal environment

Abstract

The roof of a building is normally considered to be the cover on its top that crowns it and roof may manifest it self in any shape or form depending whether a roof is experienced from within an architectural space or with out perception of it .Among the building envelop elements, the thermal importance of roof in tropical buildings is immense. Due to the sun angles in the tropics, roofs are exposed to the sun more often than the walls. The solar latitudes in the lower tropics in particular are so high that all slopes of all roofs are exposed to the sun virtually from sun rise to sunset (Fig. 1a ) .Thus, climate-conscious building designers in the tropics refer the role of roof plays in sun protection as the "Roof Problems"(Cf. Koenigsberger & Lynn, 1965: 7ff) Refference -An experimental study of the effect of roof cover on indoor thermal comfort, Emmanul M.R. (December 2000), a report submitted to the senate research committee of the university of Moratuwa ,( src grant no 2000/01/02 ) Additionally, roofs are important in rainwater runoff in the wet tropics. Materials and methods of construction that keep the rain water away are important considerations in this region. Roof is also the costliest among the super -structure elements in a low cost tropical building and its aesthetic appeal too, cannot be ignored in the tropical context. The ceiling of a given space defines the immediate upper limit of that space and may refer to the under side of the roof itself . The space of the ceiling can be manipulated as desired. The ceiling may even exit as living and ceiling of a particular space could be the floor of a space above it. Countries in the tropics, which form a wide belt around the middle of earth, do not share a univalent cultural or social frame Topography creates some climatic irregularities like typhoons and tropical cyclones. But generally, the climate is characterized by intense sunshine, heavy rain fall, prevailing winds, high humidity and equable temperatures. Evaporative cooling is greatly reduced due to the high humidity, which averages about 75% or more ( Temperature average between 22 C and 32C with only minor seasonal variation). Climate is clearly one of the prime factors of culture and form of built environment.