Impact of Brightness on Glare Perception when Using Shading Fabrics

Access to daylight and views out are usually recognized as beneficial to occupant comfort at the workplace. Simultaneously, discomfort glare due to direct sunlight is a known source of occupant dissatisfaction. Shading fabrics with low openness factor have been identified as capable of mitigating this source of discomfort. Yet, as these fabrics tend to be dense, views out and illuminance can be limited. Our objective is to evaluate the effect of shading control when it comes to the visual comfort reported by occupants interacting with such blinds. We first exposed participants to a space with the shading fabric down and, in a second session, allowed them to freely position the blind. Our usable sample included 24 participants, and the sun was visible through the blinds within their field of view.Three quarters of the participants raised the blinds in the second session primarily to increase the light levels and have better view out. Glare assessments showed that despite the opening of the blinds –and thus the significant increase in illuminance–, perceived discomfort glare did not increase. This result was in line with the Daylight Glare Probability metric, whose contrast term is able to counteract for the increase in saturation.