ALTERNATE COMPLIANCE APPROACH FOR ENERGY EFFICIENT ENVELOPE DESIGN IN INDIA: FOCUS ON ROOF SHADING

Abstract

Promoting energy-efficient building designs is necessary for reducing global energy consumption and achieving carbon emission targets. Building energy codes largely guide the design of energy-efficient buildings, with a strong emphasis on the building envelope that regulates indoor thermal conditions. Building energy codes typically offer primarily two compliance approaches: the prescriptive approach and the Whole Building Performance (WBP) approach. While the prescriptive approach provides exact specifications for each building component, the WBP approach allows Building Performance Simulations (BPS) to assess the building as a whole. However, designers often find WBP challenging, especially at the early design stages, due to the level of information WPS demands in the early design stages. On the other hand, the prescriptive approach often lacks flexibility in integrating innovative passive design features in the design process that can enhance energy efficiency early. Acknowledging the importance of passive envelope design features (PEDFs), which can offer benefits equivalent to the widely used prescriptive measures such as thermal transmittance of envelope components, this study advocates alternative compliance for such PEDFs, helping designers to make early design decisions in incorporating the PEDFs. This research aims to develop an alternate compliance approach for integrating PEDFs into the Energy Conservation Building Code of India, facilitating broader adoption and optimisation in building designs. This study starts by identifying prominent PEDFs, prioritising them, and developing an alternate compliance tool for the widely used and most impactful PEDFs. The research commences with a systematic literature study to identify PEDFs that significantly impact the building’s energy performance. Out of 14 such identified PEDFs, 13 PEDFs are found to be not included in the Indian energy codes through a prescriptive approach. The next step involved a questionnaire survey of 214 architects across India to assess the popularity of the PEDF, the barriers to its adoption in early designs, and the significance of early design tools for energy efficiency; along with feedback from 30 subject domain experts on the impact of the PEDF on enhancing energy efficiency. The survey results were analysed using the CRITIC and TOPSIS methods to prioritise various PEDFs for their potential inclusion in the building energy codes. Among the identified PEDFs, the Parasol roof/shaded roofs demonstrated the highest TOPSIS score, indicating the PEDF’s potential to be included in the energy codes through an alternate compliance approach. Therefore, the roof shading was further investigated for the development of an alternative compliance.