Understanding View Direction in Relation to Glare in Daylit Offices

Visual comfort is one of the main concerns for the integration of daylighting strategies in workspaces. Depending on the occupants’ seating position, light distribution in the field-of-view (FOV) can range from interesting highlights to visually discomforting situations which makes visual comfort highly dependent on dynamics of occupants’ view direction in the room. These undesirable situations, known as discomfort glare, have also been recognized as being the main drivers to change the façade setting. Considering the importance of daylight on human health, performance and spatial appraisal, it becomes clear that a reliable assessment of discomfort glare is critical in order to move towards performance-integrated daylighting design solutions in workspaces. There are several discomfort glare metrics that can be used at the design phase to predict discomfort glare risks. These metrics are basically drawn upon the same four physical quantities: the glare source luminance, size and position, and the general field of luminance that the eye adapts to. A major limitation, shared by all known glare metrics, is that the dependencies of glare on view direction are ignored and the calculated glare is only valid for a specific view-direction and seating position. This study seeks to eliminate this limitation through a deeper understanding of the dynamics of view-direction as a result of light variations across the FOV. The adopted methodology relies on experiments where the eye-movements of human participants are measured in a parameterized office-like room under day-lit conditions. The hypothesis is that there are clear view direction distributions patterns under different lighting conditions which will ultimately have a significant effect on evaluations of discomfort glare and lead to better integration of glare-free daylight solutions in buildings design.

Presented at:
VELUX Daylight symposium: New eyes on existing buildings, Copenhagen, May 14-16, 2013

 Record created 2013-09-10, last modified 2018-03-17

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