Roof covering as a energy saving atribute in tropical climate

Abstract

Shelter is a basic need of the human being. People want a shelter to protect from natural elements like sun, wind, rain and heat. Roof is not produced suddenly, it is a success result of our forefathers, and their experiments and the experiences. At primitive stages they lived under trees, in large cavities of tree trunks, or in caves to protect themselves from the natural disasters. They started to build rough shelters when they were unable to find caves, during the rainy seasons. With passages of time and the civilization they felt the need to settle permanently. The roof is the building component most exposed to the climatic elements. The impact of solar radiation on clear day in summer, the loss of heat by long wave radiation during the night, rain etc all effects the room more than other part of the structure. In hot countries it is believed that the roof is the main heating element of the house. In majority of cases this is true because the roof is incorrectly designed. The external surface of the roof is often subject to the largest temperature fluctuation depending on it's type, and external color. Eg: type of roofs, -Asbestos roofs -Tile roofs -Zinc alum roofs -Concrete roofs colors of roofs -Light colors - Dark colors Light colored roofs are reflects the heat and ensure a comfortable condition inside the building. According to that roof can be divide into two main categories. 1) Solid homogeneous or composite heavy weight roof. 2) Lightweight roof With regards to the tropical environment the roof is the most important element of the building in case of energy saving and regarding to the thermal comfort of the occupants. Because the roof remains unprotected while almost all other component are protected against the radiant heat load from the sun and the sky. Walls are protected from the eave and roof against the sun. By Sun shading and eaves windows and doors are protect against the sun. But the roof is the only element remaining unprotected. From roof the heat will be conducted in to the building. The amount of heat transfer in to the building will differ according to the various roofing materials. Such a way countries in warm humid tropics suffer from a lack of satisfactory knowledge on this fact and loosing their money. From this research an attempt is made to identify the most appropriate roof for the tropical thermal environments which would help to save energy, due to it's thermal performance capacity, by comparing the thermal performance of commonly used roofing systems.