Fenestration Requirements in Green Building Rating Systems: From the Perspective of Naturally Ventilated Buildings

Efforts in the building industry toward sustainable development are exemplified by green building rating systems. These systems establish sustainability criteria for certification, encompassing various aspects of construction. In India, Green Building Rating Systems (GBRS) mandate fenestration requirements, including aspects like overhang depth, Solar Heat Gain Coefficient (SHGC) of glazing, and minimum daylit area. When assessing cost considerations, many buildings opt for the SHGC parameter over overhang depth. For air-conditioned buildings, low SHGC values significantly curtail cooling loads and energy consumption. However, the benefit of reduced SHGC values is less pronounced in naturally ventilated buildings, where windows remain open for extended periods. This study employs building simulation to meticulously analyze the cost and advantages associated with implementing mandatory fenestration requirements in naturally ventilated buildings. The findings underscore that adopting low SHGC glazing in such buildings compromises daylight aspects with limited enhancement in thermal comfort, yet results in substantial cost escalation. Consequently, the study advocates for a relaxation of mandatory fenestration requirements in naturally ventilated buildings. Based on the above study the mandatory SHGC requirement was relaxed from 0.25 to 0.45.