Energy performance of windows in office buildings considering daylight integration and visual comfort in hot climates

In hot climates, the exterior envelope of office buildings can significantly contribute to the building's energy consumption. Windows are considered as a major source of heat gain and can contribute to the reduction of energy when daylighting is integrated with artificial lighting. However, with daylighting, the possibility of visual discomfort is likely to arise due to the uncontrolled light. The present study focuses on investigating the energy savings when daylight and artificial light are integrated while maintaining visual comfort. In order to assess visual comfort, both glare index and DaylightFactor are studied. A typical office in a hot climate is modeled using the simulation program, DesignBuilder. We predict the energy and visual performance for three different types of glazed windows. For all types of modeled windows a significant reduction in the annual cooling and building energy consumption was observed. For example, a 14% reduction in total building energy consumption was obtained with daylight integration for the double-glazed clear glass windows and a 16% reduction was obtained for double-glazed low-E windows. It has been observed that in all cases visual comfort was not achieved. By employing automatic interior shading control, visual comfort was achieved with no significant reduction in energy savings. (C) 2015 Elsevier B.V. All rights reserved.