Daylighting Assessment and Optimization: A Case Study in an Office Building

Daylighting is often recognized as an energy-efficient tool that lowers down consumed energy in buildings to offer visual comfort and in turn rhythms occupants’ performance and productivity. This paper conducts a simulation study to evaluate and optimize harvesting daylighting in an existing office building in Bahrain. To this end, three passive solutions were investigated namely window-to-wall ratio (WWR), surface reflectance, and building orientation to examine their influence on daylighting and thermal gain. The approach was numerically exemplified simultaneously, i.e., WWR was increased to 30%, walls and ceiling reflectance were set to 80%, and rotating the building orientation 20° degrees from the true north direction. For the suggested model, it was found that about 14% of the building spaces were exposed to excessive daylighting, 36% of the spaces show an excellent level, 26% were good, 5% were moderate, 19% were still at a poor level, and 0% has a bad daylighting level compared with 12% of the existing model. In addition to 60% and 66% increment of total and sensible cooling load respectively, the wall transmission load decreased by approximately 23%. The window transmission load increased about three folds and half; the solar load also increased approximately four folds. Therefore, building designers should achieve the balance between harvesting daylighting and thermal gain while sizing windows, choosing wall reflectance, and building orientation.