Daylight simulations can be divided into static and dynamic methods depending on whether they consider a single or a series of consecutive sky conditions. The results of a conventional, static daylight simulation are either photo-realistic images or illuminance values at certain points of interest in a building under a reference sky. (E.g. the CIE overcast sky in case one is to predict the daylight factor.)
As natural daylight is extremely dynamic and cannot be stored, static daylight simulations are only of limited usage. Instead, it is instructive to calculate the daily and seasonal development of indoor illuminances in order to evaluate the effectiveness of a given daylighting concept. Dynamic daylight simulation methods yield the time development of indoor illuminances under multiple sky conditions and the resulting annual illuminance profilesmay serve as a basis to quantify the energy savings potential of manual and automated lighting controls and/or predict how the overall daylight situation might be perceived by the users.
DAYSIM is one of several dynamic daylight simulation methods have been proposed in the past which yield hourly mean indoor illuminances for a given building geometry. A comparison of a six different RADIANCE-based dynamic daylighting simulation methods yielded that daylight coefficient approaches are the fastest and most reliable methods to simulate the short-time step illuminance development in a building (see reference Reinhart and Herkel 2000).