Daylighting strategies in tropical coastal area: A lesson from vernacular houses

Abstract

The provision of daylighting within a building performs an essential function, not only for health and visual comfort but also for energy efficiency in lighting. In tropical areas, however, excessive sunlight radiation and intensity have become a common problem in providing a sufficient amount of daylight, because they can lead to overheating. Several daylighting strategies are often employed by vernacular houses to provide daylight and to avoid heat radiation and glare. These strategies often use ray-ban glass windows material, as well as external and internal shading devices. This paper aims to investigate daylighting strategies in tropical coastal vernacular buildings and their potential application for improving daylighting performance in modern houses in the same climate. The daylight performance of three houses in a tropical coastal area was investigated via field study. The samples were chosen purposively based on construction, building material, building height and window material. Outdoor and indoor light illuminance were measured simultaneously. Indoor measurement points were placed at a height of 0.7 meter above the floor level, with 1-meter space grids. The daylight factor and illuminance level were used as performance indicators. The results indicate that the sampled houses perform poorly in regard to daylighting. This condition was caused by factors such as small-sized windows, the use of Ray-ban glass combined with the use of curtains that blocked almost 30% of daylight. Better daylighting conditions were observed in rooms with large openings (20%-40%).