Room and window geometry influence for daylight harvesting maximization – Effects on energy savings in an academic classroom

Lighting systems have a fundamental role for the overall buildings energy consumption. Therefore, remarkable efforts are required for optimizing the lighting systems energy use and for finding new daylight harvesting solutions. In this paper, the impacts on daylight harvesting provided by different room and window geometries and their effects on energy savings are presented. An academic classroom with only one window is chosen as case study and it is supposed that the window orientation is modified according to the four cardinal points. A climate-based approach was chosen for the multiple simulations, carried out via DIVA software, by assuming: square and rectangular classroom geometries with the same total area; square and rectangular window shapes having Window to Floor Ratios (WFRs) equal to 8% and 12%; two different dimmable lighting systems, in order to quantify the energy savings, by considering fluorescent and LED dimmable lamps. The daylight analysis, performed by evaluating both the Daylight Factor (DF) and the Daylight Autonomy (DA), showed that room and window geometries have high influence on daylight harvesting maximization, allowing remarkable energy savings (up to 48.5%) with respect to non-dimmable lighting system. In particular, the best energy result, equal to 467.5 kWh/yr, was obtained with rectangular room and window geometries coupled with LED lamps and WFR equal to 12%.