Daylight Characterisation And The "View Through" Index Of Glazing Systems With Obstructions

Allowing a good vision of the external environment is one of the most important functions that daylighting products are expected to perform in building architecture. Yet, hiding a particular room or office to sight is needed sometimes to ensure privacy or for aesthetic purposes. In both cases, the evaluation of the vision (or degree of vision) allowed by a glazing system is usually based on personal perception. A quantitative evaluation of the degree of vision has been proposed by REVIS, a European project concluded in 2001 where a new parameter, called View Through Index, has been introduced. Its calculation procedure is illustrated in this paper.