The selection of brise soleil shading optical properties for energy conservation and glare removal: A case study in Qatar

Energy efficiency in buildings is crucial for the design of sustainable cities, especially in hot climates where demands are high. This study investigates the impact of the shading optical properties on the space energy demands when brise soleil is installed in offices with one fully-glazed facade in four different orientations. The criteria for the selection of best shading property are an office with minimal possible total energy demand and maximum outdoor view without any occupant sensation of visual discomfort caused by glare at any time of the year. In addition, this study examines the feasibility of integrating light dimming control to these offices. A simulation model of an office space with external shading on a fully-glazed facade in one pre-selected orientation was developed and validated. Parametric studies on the shading reflectance and transmittance properties were conducted and their effects on spaces energy demands were observed for Qatar's climate, mimicking a developing country with harshly hot weather conditions. In south-oriented offices, savings caused by the addition of brise soleil reach 36.3%; unreflective or barely transmissive slats are recommended and light dimming control is unjustified. Moreover, unreflective opaque shading without light dimming control is found to be optimal in east and west-oriented offices as it saves 37.2% of the space overall energy demand. In contrary, installing highly-transmissive shadings with light dimming control is justified in north-oriented offices as it keeps full outdoor visual sight and still saves energy of up to 11.6%.