Rapid urbanization has exacerbated issues like heat islands, stormwater flooding, and increasing solid waste production, which has led to find sustainable solutions in urban infrastructure. Green roofs are the nature-based (NBS) ideal solution to mitigate urban heat island and have several ecosystem services such as thermal regulation, water management, and carbon sequestration. Nevertheless, traditional systems are based on resource-dense substrates that have strong embodied carbon and structural load. This review discusses how circular manufacturing and waste-to-resource can be implemented in the production of green roof materials with compost, biochar, and industrial by-products like fly ash, slag, and recycled construction waste. The review provides an overview of the global and India-specific studies, in which Indian studies have reported water-retention rates of between 58-68% and high biomass plant gains, whereas global studies have recorded a reduction in surface temperature by up to 10 °C and a reduction of life-cycle CO2 emissions by approximately 35% compared to conventional systems. The policy frameworks are discussed using the Smart Cities Mission, GRIHA (The Green Rating of Integrated Habitat Assessment), IGBC (Indian Green Building Council), and the case of Bengaluru, Delhi, and Hyderabad. The article highlights the new synergy between NBS and sustainable manufacturing to implement green roofs as a way forward to resilient, resource-efficient, and climate-responsive Indian cities.
Thyagaraj et al. (Mon,) studied this question.