Evaluating daylighting of glazed atrium spaces through physical scale model measurements under real tropical skies condition

This paper presents findings from a physical model investigation of an atrium building with four type of structured roof are shown. The experimental investigation allowed the author to evaluate daylight penetration in the atrium, while the adoption of varied modern structured roof constructions for the atrium allows one to obtain an insight into their effect upon the variation on daylight distribution patterns in terms of Daylight Ratio on horizontal surface. Intermediate skies revealed a complex pattern on daylight performance in the atrium attached by varied roof structure. From the results, it is clearly shown that, a high contribution of daylight penetration appears at the centre nearest to the atrium opening, while the transmittance of the atrium roof structure decreased the illuminance level at the corner by 50%. The flat roof has the highest daylight illumination for both skies condition The study also found that, under overcast skies, critical attention should be made to the corner location of the atrium especially for northand west-facing atrium surfaces as the illuminances greatly decreased for all type of roofs. The atrium roof shapes and their structure systems, orientations to the sun and skies conditions are important parameters in the daylighting design of atrium buildings. The types of sky conditions in different climate region begin more significant parameters to be included when determining the daylight performance for the atrium building. Key-Words: Daylighting, Atrium, Physical Model Measurements, Illuminance, Daylight Ratio, Tropical Skies