Daylight availability in an office interior due to various fenestration options

Abstract

Adoption of daylight as an energy efficiency strategy is especially relevant for a climate like Malaysia, as the country experiences long sunshine hours throughout the year. An important aspect of effective daylight strategy is the performance of the window in permitting daylight entry. This paper presents a study conducted to account daylight availability in an office interior un der various fenestration options; namely window-wallratio (WWR), glass types and application of external shading devices of varying depth. The study used IES RADIANCE software and the Daylight Factor method to analyse its outcome. Daylight Factor (DF) was used as the basis to estimate the percentage of daylit floor area of a generic 4.5m deep office cell. The optimum WWR to achieve the maximum percentage of daylit floor area for a 4.5m deep room are 40%, 55% and 65% for clear, tinted and reflective glass, respectively. The results from the daylight availability study also shows that application of simple horizontal shades does not significantly affect the amount of daylight indoor. In fact, application of external shades improves the daylight distribution whereby the illuminance intensity in areas closer to the windows were reduced, providing a gentle daylit indoor.