Towards daylight inclusive bye-law: Daylight as an energy saving route for affordable housing in India

• Modifying building components can effectively improve UDI ranges between 200 and 1000 lx and drive energy saving upto 26%.
• Energy Management Matrix (EMM), the function of built parameters and UDI, is devised for energy saving decision making.
• A methodological framework for a policy toolbox is proposed as a route towards designing daylight inclusive building bye-law.

Building sector in India consumes about 33% of total electrical energy use, out of which 25% is accounted by the residential sector. This can be effectively reduced by utilizing daylighting as an essential component of building design strategy. Indian building codes lack specific daylight-inclusive design guidelines, which can provide policy support in reducing the energy consumption. In this study, energy sustainability through daylighting is studied with respect to daylight performance of a middle income, residential apartment in the city of Mumbai. Useful Daylight Illuminance (UDI) is used as the performance metric. The effect of built components like window-to-wall ratio (WWR) and orientation on the UDI ranges was studied. Occupancy behavior was modelled using an UDI threshold of 500 lx, and an energy management matrix (EMM) was derived. It has been found that at south-east orientation and at 20% WWR, the base-case building would save up to 26% lighting energy. Finally, a methodological framework for developing a policy toolbox using EMM was proposed as a route towards designing daylight inclusive building bye-law.