Optimizing Building Fenestration Design for Daylight and Energy Savings in Low-Income Housing: Case of Mumbai, India: Fid-Bau Portal

Optimizing Building Fenestration Design for Daylight and Energy Savings in Low-Income Housing: Case of Mumbai, India

Kumar, Nikhil / Bardhan, Ronita

The low-income housing of dense metropolitan cities focuses solely on occupancy maximization, thus significantly neglecting indoor livability parameters energy-saving potential and daylight efficiency. The existing unit designs lack rational insight on fenestration detailing window size and location, which, when modified, impacts the indoor daylight levels and its corresponding energy demands. This study unveils a comparison of two scenarios, one considering the single building without context, and the second case considers the contextual effect of surrounding urban geometry on daylight performance. This work bridges the existing literature gap in connecting fenestration design through an optimization route. While most optimization studies deal with early design stage strategies, this study looks into the post-construction stage using retrofit and refurbishment strategies. A systematic parametric design framework was adopted for rating fenestration designs based on illuminance indicators like Daylight Autonomy (DA), Daylight Factor (DF), and Usable Daylight Index (UDI). The simulations were performed at the neighborhood level considering the impacts of nearby hyper-dense urban geometry on a given building for hot and humid climate. The results suggest that out of various fenestration design parameters, the window size was observed to be the most significant in affecting indoor daylight levels. An increase in window size from 10% WWR to 30% WWR significantly impacted daylight metrics like DA and UDI. Compared to the building without context, the contextual simulations showed that the lower floors received deficient levels of daylight, whereas the upper floors maintained the right amount of constant daylight for both the scenarios.