The Opportunity of Cool Roofs to Mitigate the Heat/Health Impacts of Climate Change in Ahmedabad
Posted March 29, 2012
I recently had the opportunity to visit Smt. Shardaben General Hospital in Saraspur, Ahmedabad, the city’s municipal hospital which serves some of its poorest communities. As we walked through the different hospital units with increasingly hot temperatures outside, Dr. Shubha Desai, Head of Medicine, discussed with us how the modifying the hospital’s roof is reducing morbidity and mortality of patients – especially infants - and helping save lives. The hospital tour was part of our on-going activities with the Indian Institute of Public Health (IIPH) and Mount Sinai School of Medicine to protect local communities from extreme heat in Ahmedabad.
Ahmedabad suffered a heat wave in 2010, when maximum temperatures reached 46.8 degrees Celsius (119.5 degrees Fahrenheit), a 50-year record high. During the scorching summer, the hospital experienced a dramatic increase in patients with heat-related medical ailments including heat stress, heat strokes, respiratory and gastrointestinal illness. The temperatures in the children’s unit, the neonatal ward, were even hotter than the rest of the hospital because it was located on the top floor of the building, creating an oven-like effect.
In a little less than a year, following NRDC and IIPH’s March 2011 workshop, which included discussions about the hospital, the neonatal unit and the impact of heat waves, the hospital took action and shifted the neonatal unit to the ground floor. With help from the Ahmedabad Municipal Corporation (AMC), the hospital took further action and converted its original black tar roof to a reflective white china mosaic. Black tar is used widely to prevent leakage in many Indian government building roofs as it is the cheapest material available. Changing the roofing material and shifting the location of the neonatal ward resulted in reduced temperatures and heat related illnesses incurred by patients. With the success of reduced building interior temperatures at Shardaben Municipal Hospital, the AMC is now planning to change the roofs of all its hospitals to make use of this easy and significant heat mitigation technique.
Roofs can play an important role in providing passive cooling to the buildings they cover. When constructed correctly, roofs can reduce the urban heat island effect that cities face, that results in the densely built urban environment experiencing hotter temperatures than its rural surroundings. Heat islands lead to higher energy consumption within urban areas to keep building inhabitants cool in the summer. Heat islands are also associated with negative health impacts such as increasing mortality rates and hospital asthma admissions.
A roof’s reflectivity is a key determinant of the surface temperature that the roof reaches and of how much heat gets passed through to the building interior. For the same amount of sunlight hitting a roof surface, a black roof can reach a high temperature of 80 degrees C (170 degrees F), and reflects only 5% of the incoming sunlight. A white roof, on the other hand, can reflect 80% of the incoming sunlight and reaches a much lower temperature of 44 degrees C (111 degrees F). The temperature of the roof can have dramatic influence over the interior living conditions of a building, particularly of the topmost floor. Modifying roof properties – such as reflectivity – can lower roof surface temperature and thus represents a hugely beneficial opportunity for the mitigation of urban heat islands and consequential negative health and energy impacts.
Shardaben Municipal Hospital’s quick action to reduce morbidity and save lives was featured during our March 2012 heat sensitization workshop led by the AMC, IIPH, Mount Sinai School of Medicine and NRDC on the “Health Effects of Heat in Relation to Climate Change – Building Resistance to, and Protecting Local Residents from, Increasing Extreme Heat in Ahmedabad.” The workshop brought together city leaders, medical professionals, and international experts to discuss ways to protect local communities from extreme heat exacerbated by climate change. It focused on medical officers and healthcare providers, who are on the front lines of treating and building awareness of the serious but preventable health consequences of extreme heat. At the forum, I had the opportunity to present the benefits of cool roofs, which represent approximately 32% of city horizontal surface and hold immense opportunity for adaption to climate change impacts.
Ahmedabad is in the top ten fastest growing Indian cities and experiences dangerously high temperatures for several months of the year. Rapid urbanization and climate change will exacerbate the heat experienced in the city in the coming years. As the city government, with groups like NRDC and PHFI, undertake groundbreaking initiatives to implement interventions to reduce heat-related health vulnerabilities and design an early warning system for dangerous heat events, incorporating cool roofs into targeted climate change adaptation strategies will make for easily implementable and very effective policy.
Co-authored with Dr. Gulrez Shah Azhar (Indian Institute of Public Health, Gandhinagar)
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