Human responsive daylighting in offices : a gaze-driven approach for dynamic discomfort glare assessment

This dissertation proposes a novel gaze-driven approach for dynamic discomfort glare assessments as a first step towards understanding human responsive comfort with respect to daylight. The objective was to observe the natural gaze behaviour in relation to glare for office spaces with the conditions implicitly constrained by real world luminous conditions. In the existing visual comfort models human behaviour is not sufficiently considered. These models employ only subjective assessments, which lack an objective understanding of the factors affecting the perceptual mechanism of light-induced visual discomfort. They so far have not integrated the inter-dependencies of visual discomfort perception and human gaze responses and have been limited to a fixed-gaze assumption directed towards the office task area. In this dissertation, a gaze-driven approach is developed and adopted in the discomfort glare assessments. The assessments were done in a series of experiments in simulated office setting under different lighting conditions where participantsâ gaze responses with means of mobile eye-tracking as well as their subjective assessments were recorded while monitoring photometric quantities relevant to visual comfort using high dynamic range luminance imaging. Integration of the luminance images coupled with eye tracking enabled us to obtain the gaze-centred luminance fields, which gives a better estimate of actual luminance values perceived by the eye, used as a basis to investigate the gaze direction dependencies of visual comfort. This PhD dissertation describes different stages of conception of this novel dynamic discomfort glare assessment method. In the experimental phase, two pilot studies were made for proper integration of the adopted methods and techniques into discomfort glare assessments. Development of several routines, algorithms and tools to identify and translate the gaze directions in order to derive the actual luminance field perceived by the participants were needed to achieve this goal. A final comprehensive experimental phase was realised to investigate gaze behaviour in response to light. As a first validation step, the gaze-driven approach was compared to the fixed-gaze approach. Then the effects of different luminance levels as well as different view outside the window on the dynamic shifts of the gaze were investigated.The developed approach demonstrates the need to integrate gaze direction patterns into visual comfort assessments, which move us beyond the existing assumption of a fixed-gaze direction towards a gaze responsive comfort.