Optimizing Window to Wall Ratio for Conserving Energy in Office Buildings for Cooling Dominant Climates with and Without Daylight Utilization

The construction of fully glazed commercial building facades responsible for high energy consumption has become a common architectural practice worldwide irrespective of the climate. This paper presents the methodology to optimize the Window to Wall Ratio (WWR) with and without daylight utilization to reduce energy consumption in office buildings for the climate of Lahore, Pakistan, using a simulation tool COMFEN. The impacts of solar heat and daylight entering through the building façade with reference to different WWR and orientation were explored for the selection of optimum WWR. The optimum WWR was selected on the basis of least energy consumption whilst achieving a threshold lighting level. When daylight is not utilized, the energy demand is minimized by the lowest possible WWR. With daylight utilization, energy demand is optimized by use of WWRs of 13% to 30% according to orientation. Optimum WWR with daylight utilization offered a more balanced solution. The methodology used in this study can be applied to any location around the world to find optimum WWR for any glazing type.