India needs strategies to combat urban heat stress

With climate change leading to a rise in temperatures and rapid concretisation exacerbating the urban heat island effect, it has become important to develop adaptation strategies to reduce and combat heat stress.

The issue was prominent at the recent World Sustainable Development Summit 2018 organised by The Energy and Resources Institute (TERI). There were many discussions on declining liveability in the cities due to heat stress and the need for appropriate policies to cope with the worsening problem.

In 2015, recorded as the hottest year so far, an estimated 4,000 people in South Asia lost their lives to heat-related illnesses. “None should be dying of heat. Heat kills,” said Anjali Jaiswal, Director, India initiative, National Resources Defense Council (NRDC). “What we are seeing with climate change is that temperatures are soaring. They are breaking records. We saw 50 degrees Celsius in India. Human body cannot survive at this temperature outside. We need cooling measures in place and simple solutions like access to ice packs, ensuring hospitals are ready to receive people and so on.”

A study done under the project HI-AWARE being led by Wageningen University and Research has looked at heat adaptation strategies in three cities — Delhi, Dhaka in Bangladesh and Faisalabad in Pakistan.

Talking about observations in Delhi, Christian Siderius, researcher adaptation and water resources, Wageningen University and Research, said, “We measured a whole range of temperatures for 2016 in Delhi to understand the heat exposures and they went from a minimum of 22 degrees to above 50 degrees, which is due to tin roofs that become like ovens in the day.”

High indoor temperatures

The study found that the minimum temperature as recorded at night by the India Meteorological Department (IMD) at the airport was significantly lower than the temperatures measured within the houses. The minimum temperature for the whole period in 2016 was 25.9 degrees but within the houses that belonged to people from medium to low income groups, the average lowest temperature was found to be 29.9 degrees, which occurred in the morning. In the hot periods, the minimum temperature was as high as 31.7 degrees.

“It means that it is the lowest temperature that is occurring at the end of the night. So it is even hotter than that,” explained Siderius. “We also saw that during that time that one of the hottest houses didn’t get temperature below 38 degrees on a single night and that’s the condition when you can’t probably sleep, you can’t be productive the next day and if it continues for a long time, it leads to health risks.”

The researchers drove around various neighbourhoods in Delhi with instruments in their cars every alternate week and found that there was an average difference of three degrees between different neighbourhoods during heat waves and some neighbourhoods were six degrees cooler than the others due to difference in shade, tree cover and lack of dense built-up areas.

Apart from climate change, rising number of vehicles, decreasing green cover, concretization, loss of wetlands and air pollutants are causing the heat island effect and leading to an increasing need for cooling strategies.

“We recorded all properties of houses, coolers, fans, humidity levels, even how the houses are exposed to the sun and now we have a better understanding of quality difference. We found that without ventilation, temperature was 36 degrees throughout the ten day period we studied, but if you have ventilation, it goes 2 degrees lower and if you can open the house, it goes further 2 degrees lower. If you have a cooler, you can bring it further down below 30 degrees,” said Siderius.

Roof relief

Experts also pointed out that modular and tiled roofs were better than tin roofs and there was a need to study existing roof solutions that can help reduce heat stress capacity in the long term. They also said that just one solution is not enough. People coming from rural areas have different coping strategies, which don’t always work when they migrate to cities since they can’t sleep in the open and on streets for prolonged periods of time.

Richa Sharma, Senior Associate with the National Institute of Urban Affairs, talked about a study that her team conducted for Delhi from 2003 to 2011 and found a strong correlation between change in land use and change in land surface temperature in the city. Green cover had a strong negative correlation while the urban cover of the city had a strong positive correlation with the land surface temperatures.

“We tried to look at the seasonal variation. It was surprising that during the summer, city actually appeared like a cool island but when we measured day and night temperature for these months, those areas were fallow agricultural land, they used to be very hot during the day but at night time, they used to cool down by 10-12 degrees while urban areas in the congested northeast area of Delhi didn’t cool down enough and nocturnal heat islands were observed in these areas,” said Sharma.

Another study done by TERI that looked at the unique case of Jharsuguda in Odisha where the primary source of heat island effect is due to coal mines and intense heat waves stressed on the need of interventions like creation of sinks like wetlands and conserving dense forests to reduction in traffic flow through new flyovers, introduction of coal washeries, among others, to make the area more liveable which is already prone to touching unliveable hot temperatures.

Heat action plans

In India, Ahmedabad has launched its own heat action plan and there are 13 cities in 11 states that have a heat action plan in place, but when it comes to building smart cities, much needs to be done to factor in policies to fight the heat stress, especially when migrant labour and people from the low economic strata are the ones most prone to it. Experts said that smart cities are not being developed in a heat-smart manner.

“When you are planning a city, comprehensive measures need to be taken. For instance, every roof should have a white roof or solar roof or multipurpose roof, bus stops and stations where people can stay cool from the heat and more considerations is needed in this area,” said Jaiswal. “The poor are vulnerable with no access to water, ceiling fans, ventilation, doctors or ice, but all of this is preventable and smart cities can be built in that way.”

Rohit Magotra of Integrated Research and Action for Development (IRADe) said, “Heat stress is not really being considered. Smart cities are mostly projects on building some infrastructures or improving the governance so this is not a holistic city. Only needs of certain geographic areas are being addressed or prioritised.” However, he added that they have worked towards inclusion of disaster resilience in smart cities project for the past few years and they are happy that at least this component has been included in ten smart cities.

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