Evidence-based design methodology for low-energy and comfortable buildings in the context of Kerala, India

Abstract

This research aimed at developing an evidence-based guide to assist practitioners and policymakers during the early stages of the design of buildings that would exhibit higher than average thermal and daylight performance. The research focuses on the State of Kerala in India where the building codes – the Kerala State Municipality Building Rule (KMBR) and the Kerala State Panchayat Building Rule (KPBR) – currently does not provide any guidelines or measures to ensure the design of better-performing buildings. Also, the criteria provided in the national level building codes and guides have proven to be inefficient.To address the aim of the research, first, the climate of Kerala was analysed. A new method of climate classification, based on the frequency of discomfort hours, was developed to identify Kerala’s regions with different climate characteristics. Based on this method, the regions in Kerala were classified into three zones: Adaptively Hot Zone (AHZ), Adaptively Mixed Zone (AMZ) and Adaptively Cold Zone (ACZ). The results show that there exist regions with different climate characteristics within Kerala. This contrasts the observations of the ASHRAE Standard 169-2013 and the National Building Code of India (NBCI), both of which classify Kerala as belonging to a single climatic zone. The NBCI method classifies the state as belonging to a Warm-Humid climate whilst the ASHRAE standard 169-2013 identifies Kerala’s regions as belonging predominantly to a Very Hot-Humid Climate.Then, the influence of design on the thermal and daylight performance of buildings was investigated by carrying out an Uncertainty Analysis (UA). The results show that variations of design parameters can account for up to 10 kWh/m2 in the thermal performance and up to 37% in the building’s daylight performance. Considering the high uncertainty, a Sensitivity Analysis (SA) was carried out, identifying floor U-value, roof U-value, window-wall-ratio, and ground reflectance as the parameters that significantly influence building performance in the different adaptive climate zones. Currently, no measures are provided in Kerala’s building codes to assist the construction of energy-efficient buildings. Therefore, these results can be used to develop prescriptive and performance-based guidelines. The results of the climate analysis and the UA and the SA were then used to develop the design guide. To provide the users with an interactive interface, the guide was designed in a web-based platform. The provision via a web-based platform was also to make it readily available to the users and allow for an update if required. A usability testing exercise was carried out with potential user groups to understand the guide’s acceptance as an early-stage design tool. The results show that the participants generally perceived the design guide as easy to use and valuable during the early stages of design. Furthermore, the participants provided suggestions on areas for possible future improvements. In the context that more than 750,000 houses will be built in Kerala shortly (2020-21 period) as part of the Government’s “Livelihood Inclusion and Financial Empowerment (LIFE)” mission project and no guidelines are provided in Kerala’s building codes to regulate the construction of energy-efficient residential buildings, it is hoped that this tool will aid the design of buildings that exhibit higher thermal and daylight performance.