Prioritizing passive envelope design features for integration into the building energy codes: a case of India

Energy efficiency in buildings is a key area of focus in the path towards net zero energy goals and mitigating climate change. Among various passive strategies for energy efficiency in buildings, building envelope shading is considered a key strategy to control solar heat gain and reduce the cooling loads in buildings. While significant focus has been given to shading glazing components of buildings, this paper addresses a critical gap by investigating the potential of shading the opaque envelope components (OECs), which include opaque walls and roofs. OECs can reduce cooling load by managing the heat ingress into the buildings. Although OECs are not widely used in energy-efficient building strategies, the passive strategies in OECS help control heat gains and decrease cooling loads, especially in hot climates. This study investigates the shading strategies of opaque OECs in a two-stage review, initially reviewing the global building energy codes to assess the inclusion of OEC shading strategies and then identifying effective shading techniques for walls and roofs through a systematic literature review. The review of energy codes reveals that very few energy codes explicitly address OEC shading with a single instance mentioned in the energy codes of Australia and India. In contrast, all the codes explicitly specify window shading as a passive strategy. The SLR further demonstrates that the shading OECs can significantly reduce cooling demands, with strategies such as overhangs, green facades, double-skin roofs, and photovoltaic panels showing up to 77% energy savings. The shading potential provides considerable scope for integrating the shading of OECs as a passive strategy that can be incorporated into the energy for better adoption in the buildings.