VALIDATION AND PRELIMINARY EXPERIMENTS OF EMBEDDED DISCOMFORT GLARE ASSESSMENT THROUGH A NOVEL HDR VISION SENSOR

Abstract

In spite of an abundant research on visual comfort models and integrated day- and electric lighting systems, the lighting engineering and research community is restricted to the use of ceiling-mounted luminance sensors, which do not faithfully reproduce the visual comfort sensations of building users in day-to-day practice. Moreover, the discomfort glare indices suggested in the past are evaluated through the luminance mapping of visual scenes generated by the wa y of a laborious High Dynamic Range (HDR) imaging process: this approach cannot be integrated into building automation. On the other hand, mitigation of the electricity demand for lighting by applying ‘easy’ photometric metrics, such as the luminance monitored from the ceiling, leads mostly to non-optimal situations regarding visual comfort and performanc e. In order to overcome these issues, a novel embedded HDR vision sensor fitted with a fisheye lens and capable of performing real-time, accurate and reliable luminance mapping together with an assessment of discomfort glare indices, is suggested. This novel device was successfully validated against the Evalglare software and its robustness on an embedded platform for long-term visual comfort assessments was demonstrated. Preliminary experiments were carried-out with two calibrated HDR vision sensors in order to deepen our knowledge regarding visual comfort in an office room of the LESO solar experimental building located on the EPFL campus in Lausanne (Switzerland). These experimental results are beneficial for the design phase of a sun shading and electric lighting control system that will be shortly evaluated on-site within the same occupied office room.