THE EFFECT OF OPENING DISTRIBUTION AREA MODIFICATION ON HORIZONTAL LIGHT PIPE DAYLIGHT PERFORMANCE

The use of daylight within an office building in the tropics provides energy savings, psychological and physiological health advantages for building occupants. In order to promote the daylight admission, the building should have a narrow depth. However, plans of modern air-conditioned buildings tend to be
deep, in order to minimize heat gain from the building envelope. A deep plan office building design limits access to daylight and generates an insufficient daylight level on the workspace distant from the side window. Horizontal Light Pipe (HLP) is one of light transport systems that can deliver daylight to these
areas. The research aim was to explain and evaluate the effect of HLP�s opening distribution area on daylight performance at deep plan-private office space in the tropics. The research method was experiment with simulation as a tool. Daylight level and daylight uniformity of the base case, HLP with an opening distribution area of 6.6 m2 were compared with the case, HLP with an opening distribution
area of 3.41 m2. The results showed that HLP with a smaller opening distribution area of 3.41 m2 could illuminate working spaces where a simple visual task is performed. A 50% reduction of HLP�s opening distribution area, from 6.6 m2 to 3.41 m2 improved average Daylight Factor (DF) as much as 6.42%. The
presence of highly specular material on opening distribution area contributed to the specular reflection of daylight before being transmitted to office space by a translucent glass. A lower illuminance uniformity ratio but still meet the recommended illuminance uniformity ratio on workspace was resulted in a smaller HLP�s opening distribution area. Considering the improvement of daylight level and high uniformity ratio resulted, HLP with a smaller opening distribution area can be applied as the main source of daylight on deep-plan office spaces.