Optimization of daylight in buildings to save energy and to improve visual comfort: analysis in different latitudes

Natural light is irreplaceable because it is a full-spectrum light, it changes during the day and it is different every day of the year. A variable illumination throughout the day, in terms of intensity and colour temperature, creates dynamic indoor environments that are more pleasant for people. Daylight needs to be controlled, especially in office buildings, to avoid discomfort glare and high luminance reflections on display screens, to provide a good lighting level even in the deeper part of a room and to reduce cooling loads. To improve the quality of light, of visual comfort and to minimize lighting, heating and cooling loads advanced daylighting systems (such as BMS, Building Management Systems) and external shadings should be used. The aim of this study is to optimize the availability of glare-free natural daylight in a building’s interior, in order to create spaces of high visual quality, where the energy demand for artificial lighting and cooling can be reduced by means of control strategies and shading devices. The same office room has been supposed at different latitudes, since each latitude needs a specific shading system . The lighting simulation has been carried out with the software Daysim, developed by the National Research Council del Canada and by the Fraunhofer Institute for Solar Energy Systems and the software Radiance, developed by Greg Ward and by the Lighting System Research group of the Lawrence Berkeley Laboratory.