Reflections on redesigning ‘Cool Roofs’ – beyond reflective coatings for energy poor communities in India

Extended abstract 8-167-26

India’s urban poor living in dense informal settlement buildings face the brunt of the climate crisis manifesting as extreme heat; an acute case of climate injustice where those least responsible suffer the most. The mainstream technology being promoted ‘Cool Roofs’ (reflective coating) are underforming in these buildings compared to claims based on ideal-condition testing by their promoters. Furthermore their unintended consequences (displacing the heat problem elsewhere – one home’s reflection is another homes’ glare), need for constant maintenance to stay reflective given high dust/pollution levels, high-cost and increased dependence on global supply chains warrant a grassroots innovation approach. The paper unpacks the 4 year evolution of development of a catalogue of appropriate-technology based affordable roof-retrofit solutions for building heat stress mitigation that have been pilot tested in 200 buildings in 6 Indian Cities. The paper outlines technical upgrades to enhance performance of external rooftop and internal ceiling radiant barriers conjugated with night-sky radiation features, enhancing modularity and reduced weight (for ease of assembling & dismantling – in turn reducing fabrication time and cost) and mitigating physical hazard, substituting industrial materials with upcycled inorganic waste or agri/forestry waste biomass, harnessing multiple climate and ecological benefits of modular rooftop gardens/green roofs, and maximizing thermal benefits of the lowest cost, locally available thermal mass material – water, to achieve thermal comfort performance superior or on par with reflective coatings. The paper also delineates the future trajectory for enhancing technology-readiness-level through harnessing multiplier effects of combinations of passive design technologies, other renewable materials (eg. human hair) for insulation, and modular low-cost sustainable active-cooling for humidity control and lower temperature in energy-poor communities.

Download presentation.