Daylight Saturation Percentage

Daylight Saturation Percentage (DSP) is a modification of Useful Daylight Illuminance that increases the lower limit to 40 footcandles (precisely 430 lux) and increases the upper limit to 400 footcandles (precisely 4,300 lux). It goes further to penalize grid point annual hour values above 400 footcandles by forcing them to be subtracted from the grid point annual hour values within the range of 40-400 footcandles. The Lighting and Daylighting Committee for the Collaborative for High Performance Schools program developed it in 2006. The graphical percent values represent the percentage of the floor area that meets the DSP criteria at least 50% of the time while also accounting for the penalty for hours above the 400 footcandle upper threshold.

References:
• Collaborative for High Performance Schools (2006), Design for High Performance Schools Volume 2, www.chps.net.