Thermal performance and cost effectiveness of massive walls under thai climate

In Thailand, traditional houses and public buildings were constructed from materials of low thermal mass. Windows and doors in such buildings are well shaded. Open windows, doors, and even gaps in the raised floor allow all interior spaces in a building to be naturally ventilated. Prior to the introduction of air-conditioning, concrete began to replace wood as walling material. New large air-conditioned buildings have glazed and closed windows so all interior spaces require air-conditioning and forced ventilation. Under the present situation, there is a tendency to believe in the merit of thermally massive walls. This paper presents results from an experimental and simulation study on comparative energy and economic performance of thermally light and massive walls that are used to enclose air-conditioned spaces. The spaces are assumed to serve three residential functions and three commercial functions. Results related to residential functions reaffirm the merits of vernacular architecture. Results related to commercial functions are mixed. However, very massive walls are not economical.

► Traditional Thai houses and public buildings are constructed from materials of low thermal mass, are well-shaded, and are naturally ventilated.
► Air-conditioning is now invariably used in commercial buildings, and has penetrated significantly in households, the walls are thermally more massive than traditional houses and buildings, and there is a belief that massive walls thermally perform better.
► Increasing thermal mass by increasing wall density only (and not the wall thermal resistance) generally leads to small reduction in cooling load for commercial buildings, but leads to increasing cooling load for residential buildings.
► Increasing wall thickness that results in increasing wall thermal mass and wall thermal resistance leads to slight decrease of total wall material and energy cost for commercial buildings up to the wall thickness of about 50 mm, but the total cost increases beyond this.
► For residential buildings, increasing wall thickness leads to increase in total cost.