Learning for the experience of the devastating heat wave in 2010, municipal authorities in Ahmedabad have recently launched a cool roofs initiative to mitigate the worst effects of extreme heat among vulnerable communities
Cities around the world, especially in India, are grappling with some of the hottest March temperatures recorded in years. The western Indian city of Ahmedabad in Gujarat is working to address these deadly temperatures through a resilience plan for heat waves, and a new cool roofs initiative focused on slum communities. Earlier this month, Ahmedabad launched its fifth Heat Action Plan, an early warning system to warn and protect citizens from the devastating health effects of extreme heat.
As part of the 2017 Ahmedabad Heat Action Plan, municipal authorities launched a city-wide initiative on cool roofs to provide access to affordable cooling for those who are more vulnerable to the health effects of extreme heat — the urban poor living in slums. Building on the long-term partnership with Natural Resources Defense Council (NRDC), a global environmental organisation, the heat action plan was developed by the Ahmedabad Municipal Corporation and launched in collaboration with the India Meteorological Department (IMD) and the Indian Institute of Public Health, Gandhinagar (IIPHG).
Nearly 25% of Ahmedabad’s residents live in slums, according to its municipality. The nearly two million slum dwellers have few options available to adapt to rising temperatures. This increases their vulnerability to heat and results in greater adverse impacts of extreme heat. In developing the heat action plan, the Ahmedabad Municipal Corporation, along with NRDC and IIPHG, identified the specific factors that increase the vulnerability of slum residents to extreme heat.
Increased vulnerability to heat
The key factors include risk factors such as lack of access to health information and strenuous outdoor work, in their home environments. Slum communities have fewer adaptation options since they often lack control over their home and work environments, with limited access to, and inability to afford, reliable electricity and cooling. Slum residents also have higher exposure to extreme heat because they are more likely to be exposed to heat since they live in homes constructed of heat-trapping materials with tin or tarp roofs, and their communities lack trees and shade.
In an effort to strengthen resilience in slum residences, Mayor Gautam Shah ran an awareness campaign including promoting measures for evaporative cooling such as placing wet jute gunny bags on the slum roofs to reduce temperatures in 2016.
Building on 2016’s efforts, the municipality introduced a cool roof initiative as part of the 2017 Heat Action Plan. The corporation intends to convert at least 500 slum household roofs to cool roofs; convert public buildings to cool roofs, including municipal buildings and government schools; and release new information, education and communication materials to build awareness on cool roofs.
Cool roofs are highly reflective surfaces that stay cool in the sun by minimizing heat absorption and emitting most of absorbed heat. Studies have shown that cool roof surfaces can be up to 30 degrees Celsius cooler than conventional roof surfaces, and can reduce the indoor temperatures by 3-5 degrees Celsius. When implemented on a large scale, cool roofs can reduce the urban heat island effect in a city and lower the energy bills of the entire city. Cool roofs include coatings and treatments such as lime-based whitewash, white tarp, white china mosaic tiles and acrylic resin coating, and provide an affordable solution for providing thermal comfort.
The focus on cool roofs started after the devastating 2010 heat wave in Ahmedabad, which provided the impetus for the heat action plan. In 2010, temperatures peaked at 46.8 degrees Celsius, a 50-year record high. During the scorching heat wave, the city’s municipal hospital Shardaben Hospital experienced a dramatic increase in patients with heat-related illness, including heat stress, heat strokes, and other respiratory and gastrointestinal illness.
The unit treating new born babies was located on the top floor of the building at the time, under a black tar roof, creating an oven-like effect with temperatures even hotter than in the rest of the hospital. The hospital saw very high mortality in new born babies that year. As part of the heat action plan, the hospital replaced the black tar roof to a white reflective china mosaic roof that reduced temperatures inside the hospital and helped provide thermal comfort.
Cool roofs are an affordable and smart solution that helps manage cooling demand and mitigate the impact of urban heat island effect. Solutions, such as the heat action plan and new cool roofs initiative, are critical to saving lives and addressing skyrocketing cooling demand in cities across India, as climate change continues to drive extreme temperatures.