ROAD TO CITY COOL

Urban India is a heat trap, but road orientation, building materials and zone-specific master plans can drastically enhance thermal comfort 

- RAJNEESH SAREEN, MITASHI SINGH AND NIMISH GUPTA

RISING EPISODES and increasing intensity of heatwaves have become quite common and a major problem in Indian cities. The threat is twofold: big cities are finding it difficult to adjust to the changing climate and need liveability improvements. Small cities, on the other hand, are on the brink of explosive growth and require "heat-proof" development. While big cities need retrofits to combat the "heat island" effect, small cities need heat-resilient master plans and by-laws.

Every city has a unique combination of natural and humanmade infrastructure and the activities resulting from them. Closely packed buildings, for instance, will generate shorter trips and hence lesser vehicular emissions that pollute the air and trap heat. More greenery and waterbodies will sequester carbon emissions and cool the ambient environment. This combination of green spaces, waterbodies and buildings is called the urban form of a city, which plays a crucial role in its heat resilience and liveability.

In 2022, Delhi-based non-profit Centre for Science and Environment (CSE) began a study to understand how different urban forms react to heat. The study, which covers 10 cities including Pune, Delhi, Kolkata, Bengaluru and Jaipur, is ongoing. But data and trends evident so far suggest steps that could help urban India fight heat.

Urban form can be broken down into and understood through physical parameters. Its key parameters include urban morphology, aspect ratio, sky view factor (SVF), blue/ green infrastructure (B/GI), floor area ratio (FAR)/ floor space index (FSI) and street orientation. At Pune, CSE recorded these parameters at 49 locations identified as the city's "heat pockets" areas where land surface temperature (LST) soars above 45°C. This is what the readings show: