Spatial brightness, horizontal illuminance and mean room surface exitance in a lighting booth

This paper presents a pilot study that has investigated the suitability of mean room surface exitance as a predictor of spatial brightness and compared these results with how horizontal illuminance predicts spatial brightness under the same conditions. The experiment took a group of 26 participants and, using a scaled booth, exposed each participant to three levels of mean room surface exitance, each delivered with three different light distributions and three different surface reflectances, resulting in a total of 27 light scenes. Results demonstrated that, under the range of conditions to which participants were exposed, a systematic relationship existed between mean room surface exitance and spatial brightness, but not between horizontal illuminance and spatial brightness.