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. Despite the promotion of ENS standards through financing programmes, insulated wall construction has not seen any momentum in residential construction.
Notably, a majority of Indian homes continue to use natural or mixed-mode ventilation strategies rather than full-house and year-round air conditioning. Our previous research indicates that, in mixed-mode buildings, wall insulation can reduce thermal comfort when the building operates in natural ventilation mode in several climate zones of India. Building on these findings, this study conducts a 50-year life-cycle cost (LCC) analysis using a calibrated simulation model for four climate zones in India, comparing the cost-effectiveness of insulated walls and efficient air-conditioning systems under two operational scenarios: fully air-conditioned mode (AC-Mode) and mixed-mode (MM-Mode).
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 residential development, developers also face the challenge of recovering insulation costs through home-sale prices, which impacts affordability. These findings highlight that, particularly in AC-Mode operation, efficient cooling technologies represent a more practical and adaptable long-term strategy for Indian residential buildings.
Keywords