Our Research Projects

The Indian real estate industry has projections of 230 million housing units in urban areas by 2047, accommodating 51% of India's population. With increasing aspirations of building occupants and a warmer climate, air conditioning demand will grow 11-fold by 2037–38 compared to 2017–18. While India's Eco-Niwas Samhita (ENS), the residential building code launched in 2018, includes a maximum Residential Envelope Transmittance Value (RETV) which calls for reducing heat transfer through the building envelope, industry practitioners are meeting this requirement by incorporating insulation into the building envelope. This paper demonstrates that for residential buildings in cooling dominated climates that are naturally ventilated for cooling, increased insulation is counter-productive. Various building envelope assemblies and insulating values are evaluated for thermal comfort conditions in a hot and dry climate. Simulations were conducted using DesignBuilder for summer conditions. Results have also been compared with measured data. The findings indicate that insulated walls can increase discomfort hours by 4% compared to uninsulated walls. In contrast, high thermal mass envelopes improve comfort hours by 3% and 8%, respectively, suggesting they are more effective for naturally ventilated buildings. The results highlight the need for re-evaluating the residential energy code as well as the current practices of implementing the energy code in India.

This paper evaluates the financial viability of investing in either wall insulation or energy-efficient air conditioning systems in Indian residential buildings. India's rapid urbanization is expected to create demand for approximately 230 million new housing units by 2047, and rising living standards combined with increasing temperature and humidity are anticipated to drive an increase in air-conditioner demand. The study aimed to determine which option - insulated wall assemblies or efficient air-conditioning - offers better long-term cost-effectiveness and adaptability for Indian residential buildings.

The Government of India introduced the Eco-Niwas Samhita (ENS) in 2018 that includes minimum Residential Envelope Transmittance Value (RETV), which minimizes envelope heat gain. However, prevalent construction practices in India, such as Mivan (monolithic concrete) technology and fired brick walls do not comply with the ENS requirements. Achieving compliance typically requires assemblies using aerated autoclaved concrete (AAC) blocks or additional insulation layers, both of which pose workmanship challenges, slow down construction, and, in the case of AAC, present their own material issues.

The results reveal that in both AC-Mode and MM-Mode, efficient air-conditioning provides a marginal economic advantage of 0–3% Life-Cycle Cost reduction across four Indian climate zones compared to insulation. Moreover, efficient air-conditioning offers greater flexibility, as occupants can upgrade to more advanced models every decade, and provides better cash-flow opportunities due to its lower initial capital cost. In contrast, insulation is a one-time installation with no scope for future performance improvement, is susceptible to degradation from poor workmanship, moisture ingress, or structural changes, and rarely ensures thermal comfort on its own.

In our study we present EUI benchmarks for NZEBs for six building types across residential and non-residential typologies and for India's five climate zones. This approach is similar to the simulation-based benchmarks used by the B3 program in Minnesota, the Cal-Arch methodology in California, and the US Solar Decathlon approach, which combine simulations with actual building data. Of the six building types we explore one in detail with a range of operation scenarios, specifically narrowing down the EUI benchmarks for mixed-mode building operation and for variable temperature set-points as prescribed in the National Building Code of India.

The contribution of this work is to provide rigorous end-use level EUI benchmarks for six building types, and to describe a method for simulation-based EUI benchmarks for mixed-mode operation with variable setpoints to highlight the difference between the standard approach and the On-Site Construction Worker Housing which additionally has the mixed-mode variable setpoint approach. The methodology used for the On-Site Construction Worker Housing results in an 80% acceptability according to the India Model for Adaptive Comfort in the National Building Code of India. EUIs of all six buildings are 60% lower than the minimum compliance with India's Energy Conservation Building Codes, providing benchmarks for efficiency levels. The end-use level EUI benchmarks are now provided to over 1800 Solar Decathlon India participants.

The building sector in India contributes to about one-fifth of the country's total CO2 emissions. At COP26, India has committed to achieving net-zero by 2070. Net-Zero Energy Buildings (NZEBs) can accelerate the pace at which India can achieve its net-zero goals. Since approximately 70% of India's buildings for 2040 are yet to be built, these can be designed, built and operated as NZEBs. There is significant scarcity of workforce and lack of training in college curricula about NZEBs. Solar Decathlon India (SDI) competition addresses this by enabling student teams to learn and design real NZEBs.

This paper reports on an analysis of the final submissions over two years to evaluate their ability to produce evidence-based designs for their projects. A similar analysis after the first year's submissions revealed areas of weakness in the students' ability to provide evidence-based designs, and additional resources and training were provided to teams and faculty in the second year to improve BPS skills. We observed that 12% more teams who provided evidence for their designs in the second year. Evidence for daylighting strategies saw the largest increase of 37%, and natural ventilation strategies were next at 18% increase.