Extract

Architects are encouraged to follow rating methods and codes to design energy-efficient buildings. However, to work with these codes, additional skills are required, and codes offer a variety of design options rather than thumb rules. In India, climate design guidelines for hot and dry region
recommend north-south orientation for building and no windows on west façade to reduce solar heat
gain, whereas plots with longer west side require windows on west façade for daylight, air and view.
Therefore, it is important to find out optimum window to wall ratio (WWR) that can provide adequate
daylight as well as low energy consumption. This paper attempt to analyse WWR with respect to room
depth, lighting power density (LPD) and glazing material to arrive at a simple thumb rule for architects.
The study is performed via Ladybug and Honeybee tools which depends on Radiance and Openstudio for
simulation, considering essential factors of daylight and energy, i.e., useful daylight illuminance (UDI), heating, cooling, and lighting load. Results showed that at 5 W/m2 LPD, 20-25% WWR gives the
minimum energy consumption as well as adequate daylight till 9m room depth. Further studies are
required to explore the effect of WWR for different climate and orientation.

Keywords: Energy-efficient buildings; daylight utilization; Useful daylight illuminance; Window to wall
ratio

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