In order to evaluate the energy performance of a building it is necessary to assess the use of daylight, as it can influence the total thermal load of the building. The main objective of this study is to evaluate the illuminance levels calculated by the EnergyPlus computer programme. This analysis was performed by comparing the daylight factor (DF) calculated by EnergyPlus with two other programmes: Daysim/Radiance and TropLux, and also by comparing external illuminance calculated and measured in Florianópolis, between 2003 and 2005. The Daylight Factor was calculated for two different rooms: square (5 m x 5 m x 3 m) and rectangular (5 m x 10 m x 3 m). The comparison of the DF obtained from three different programmes indicated that EnergyPlus cannot solve the internal reflectance properly. The comparison the measured external horizontal illuminances and the one calculated by EnergyPlus indicated a difference higher than 100% for the diffuse illuminance.
Daylight; Illuminance; Computer simulation