Optimizing Window Size and its Sunshade in Four Main Directions of Residential Buildings in Mild Climate by Integrating Thermal and Lighting Analysis

As part of sustainable architecture principles and practices, designers need to define building's architectural requirements based on climatic conditions, environmental preservation and reduction in energy consumption. The natural energy sources such as solar radiation affect thermal and lighting performances of buildings depending on its facade characteristics. Traditionally, buildings thermal and lighting analyses are employed independently. As non-linear relationships are often disclosed, an integrated thermal and lighting approach is necessary to optimize the façade configuration. This paper presents an integrated model of thermal and lighting energy simulation which investigates 1650 window configurations, and sunshade size in a residential building in a mild climate to find the optimum solution. The integrated thermal and daylight simulations are carried out using Energy PlusV8-1-0, Daysim 1.08 and Radiance 2.01 software. Calculations are performed on hourly basis for an entire year. First, climatic parameters are validated by on-site measurement. Then all thermal and lighting parameters of the simulated model are defined. Next, the optimal results of the window and sunshade characteristics in four main dimensions (South, North, East, and West) are presented by genetic algorithm approach. The results show that, the window orientation affects up to 10% on energy saving, and horizontal windows with higher sill levels are more energy-efficient in south and east orientations. The optimal sunshade angel of the south orientation is 65-85 degree and its optimal range of Window Wall Ratio(WWR) is 15-25%.