Investigating Optimal Window to Wall Ratio towards Reducing Cooling Energy Consumption of Offices in the UAE

With the widespread use of curtain walls especially among office buildings, offices stand to be in an abundance of light and are among the largest consumers of electricity. According to previous research, more than 50% of the energy losses happen through the building envelope. The window-to-wall ratio (WWR), or the percentage of glazing in a building's envelope, has a great impact on multiple performance aspects of an office building across its life cycle, including energy consumption, daylighting, material use, and occupant comfort. Major concerns arise in the local extreme hot climate regarding the lack of consideration of WWR causing an increase in offices' cooling energy consumption coupled with recurrent occupant discomfort. A higher education (HE) office building located in United Arab Emirates University (UAEU) campus has been selected as a case study, to focus on the area bounded by the west façade. Model simulation by means of DesignBuilder software investigated the optimum WWR towards minimizing annual cooling load and solar heat gain, whilst maintaining adequate daylighting levels indoors. Furthermore, daylighting levels were validated by complying national and international standards such as Estidama and WELL building standard. Results found the optimum WWR for the south façade as 20% which achieves the best building energy use performance, with 14.5% reduction in overall building energy consumption from the existing baseline model. In parallel, indoor lighting levels were comparatively enhanced throughout the WWR range 20%-30%. These findings provide design recommendations to promote applying passive energy optimization strategies towards improving occupant comfort in office buildings.