An experimental and numerical analysis of daylighting performance for an office building

The urgency of increasing energy efficiency in new building design and retrofits has moved lighting simulation into a central role in sustainable lighting design. In fact, good daylighting design can result in energy savings and can shift peak electrical demand during afternoon hours when daylight availability levels and utility rates are high. The shape of the building and its orientation, the reflectances of the building surfaces and the glazed areas are important parameters in the daylighting design of buildings. Glazing systems can cut energy consumption and the associated pollution sources, reduce peak demand, enhance daylighting performance, and improve occupant comfort. This paper presents the results of a numerical and experimental comparison between the performances of an office building with and without external sunscreens. The aim is to analyse the illuminance distribution and some investigations have also been made with regard to the effect on daylight in rooms when sunscreens are used. The experimental results were obtained using an office building scale model and a sky simulator. The numerical results were obtained through the ray-tracing program Radiance that accurately predicts the light levels and that produces photo realistic images of the architectural space in all sky conditions: illuminance values are obtained respectively through reference point measurements. The daylighting performances of the office building model with and without the sunscreens have been compared and analysed.