Illuminance

The study investigates the use of local trees in the UAE to improve visual performance and lighting quality in typical classrooms. The methodology depended on analysis of luminance ratios and illuminance levels using simulation (Radiance.) The effect of two design variables (i.e., tree type: Ghaf and Neem, and tree spacing: 2m and 4m parallel to outside north wall, on task’s illuminance levels and interior-surfaces’ luminance levels were investigated. Lighting quality and visual comfort issues such as acute contrast, high brightness, and daylight distribution were discussed.

A subjective experiment was conducted using 15 college-aged subjects of both genders in order toevaluate their physiological and psychological reactions, performance and fatigue under the differentcombinations of indoor humidity, local air velocity and illuminance.The five-hour exposure periods were divided into three sections of 1.5 hours by 10-minute breaks.During each section, subjects performed 3 times of 20-minute task.

Illuminance and daylight availability are important parametersin daylighting design for passive, low energy architecture. In Malaysia, the only climatic parameter that can be used for determining daylight availability is global solar irradiation, which is measured at major meteorologicalstations around the country. However, it is possible to estimate the global illuminance from global solar irradiation data if the global luminous efficacy is known.