Prediction of climate-based daylight metrics by simulating monthly median illuminance

Daylight performance in indoor spaces nowadays are commonly represented by the currently emerging climate-based daylight metrics (CBDM), which can be directly predicted using sophisticated daylight simulation tools. Several alternative simulation tools are not capable to directly simulate the CBDM but are capable to simulate point-in-time illuminance, which can be employed as proxy to calculate CBDM. This paper aims to demonstrate the use of monthly median illuminance in a hypothetical indoor space, to predict daylight autonomy (DA) and useful daylight illuminance (UDI), based on two design parameters, namely window-to-wall ratio (WWR) and facade orientation. Four variations of WWR, i.e. 10%, 30%, 50%, 70%, and four variations of orientation, i.e. north, east, south, west, were simulated using VELUX Daylight Visualizer, while observing median illuminance at 08.00, 12.00, and 16.00 hrs each month, to predict DA300lx and UDI100∼2000lx. Based on simulations, WWR is found to have the most impact on the UDI100∼2000lx.