Come summer, and the roads radiate heat, hospitals report heat strokes, the government asks citizens to stay indoors, and everyone blames that new villain in town - climate change. But nobody really thinks of that concrete-burnt clay bricks-glass structure coming up right under their nose. Or the asphalt that ate up the greenery.

Time was when Indian cities were built with materials and designs that had cooling systems at the heart of the plan. Monuments like the Red Fort in Delhi, the medieval quarters of Jaisalmer, and parts of old Hyderabad bear witness to this wisdom even today. Delicate water channels, a river next door, limestone or sandstone structures, central courtyards, stepwells… they all contributed to keeping the ambient temperature down.

But the neighbourhoods of today, built fast and furious to accommodate rapid urbanisation, are heat traps.

“The intensity of heat experienced within Indian cities is largely shaped by how we have planned and expanded them,” Mitu Mathur, Director of Delhi-based GPM Architects and Planners, told The Secretariat.

Such heat also affects different income categories differently, with those having no choice but to work outdoors as well as those unable to afford cooling equipment bearing the brunt.

“If green networks, water systems, shaded public spaces, and climate-responsive urban design are integrated into the planning process from the outset, cities can accommodate growth while remaining resilient to rising temperatures,” said Mathur.

Deaths attributed to heatstroke and sunstroke in India rose from 804 in 2023 to 1,832 in 2024, an increase of 128% in a single year.

“While a combination of meteorological factors – including atmospheric pressure, wind patterns, precipitation and climate change - cause heat waves, Indian cities’ buildings have a lot to do with the heat residents feel,” says a report published by the Netherlands-headquartered Global Centre on Adaptation (GCA).

That means faulty designs and unsuitable building materials.

“Indian cities are covering themselves in imported or synthetic materials that perform worse in our climate. Fixing it requires both policy signal and design awareness,” said Rishabh Jain, Director of Petros Stone LLP, a natural stone manufacturer and exporter.

Vanishing Landscapes

Urbanisation changes how land behaves.

Fields become buildings. Open spaces become parking lots. Wetlands become real estate projects. Tree-lined avenues give way to wider roads and denser construction. Naturally growing native plants that require less water and tolerate hot weather make way for the horticulture department’s design priorities, which is essentially beautification.

These changes may seem insignificant, but they alter a city’s ability to regulate temperature.

The Urban Heat Island effect comes into play, whereby built-up areas become significantly hotter than surrounding rural regions because concrete, asphalt, glass, and burnt red clay bricks absorb heat during the day and release it slowly through the night.

The design also matters. Cities have expanded vertically as well as horizontally.

Tall buildings in high density areas hinder the passage of air by obstructing the sky and lowering wind speeds, the report says.

“For decades, our cities have grown through unchecked horizontal sprawl and real-estate-led development that prioritised maximising built-up concrete over environmental performance. In the process, tree cover, water bodies, open spaces, and natural drainage systems have been significantly reduced, weakening the natural systems that regulate urban heat,” Mathur said.

According to the Ministry of Environment, Forest and Climate Change, India diverted 1.73 lakh hectares of forest land in the last decade to mining, hydropower, irrigation, and road projects.

Historically, Indian cities possessed natural cooling systems in the form of lakes and ponds. Wetlands absorbed excess heat. Open land allowed air circulation. Rivers and green corridors acted as thermal buffers. But many of these natural assets have steadily disappeared.

A recent study by the Centre for Science and Environment (CSE) found that Delhi’s land surface temperatures touched 60.77°C in some locations during summer.

More than 75% of Delhi's area now experiences recurring heat stress, while over half its municipal wards have more than 75% of their land exposed to persistent heat stress.

The study found that Delhi's core urban areas cool 3.8°C less during the night than surrounding peri-urban areas, meaning heat remains trapped around the clock.

Green Inside, Not Outside

India’s urban planning framework was largely designed around growth focused on land use, housing, transportation, commercial development and infrastructure provision, but thermal comfort is often missing from the plan.

There is a blind spot in the urban development model when it comes to how construction materials affect ground temperatures and public spaces.

Green building conversations are almost entirely about what happens inside the building. Energy ratings, heating, ventilation, and air conditioning (HVAC) efficiency, glass facade performance, LED lighting. All important. But outside the building, the conversation stops.

Streets, plazas, footpaths and parking lots are urban heat islands. When an entire city block is paved with dark asphalt, surrounded by concrete kerbs, and a glass tower that reflects heat onto the pavement, it creates a furnace at the street level.

Jain said, “Green building certification in India doesn't adequately account for the thermal impact of external material choices on the surrounding public environment. A building can be Platinum-rated and still contribute significantly to ground-level heat stress in the spaces around it.” A Platinum-rated building is certified at the highest tier of global sustainability by the Indian Green Building Council.

Today, air-conditioners have become a necessity rather than a luxury. Households, offices, malls, schools, and commercial establishments invest heavily in mechanical cooling. Yet air-conditioning only cools indoor spaces while releasing heat outdoors.

Ashish Goel, CEO & Co-founder of Optimist, a new age AC company, said that air-conditioning will remain necessary, especially as summers become harsher, but cannot be the only solution.

“If buildings are poorly designed and cities continue to trap heat, ACs will only work harder, consume more energy, and add pressure on the grid. The first layer of cooling has to be ingrained from a design perspective. Climate-resilient buildings, better insulation, reflective roofs, shaded windows, natural ventilation, and trees in urban areas can all reduce indoor heat before mechanical cooling is needed,” Goel said.  

Smart Cities Mission

The Smart Cities Mission, launched in 2015, sought to modernise urban India through investments in roads, transport systems, water supply, sewage networks, command-and-control centres, digital governance platforms, and public infrastructure.

By the time it concluded in March 2025, more than ₹1.64 lakh crore worth of projects had been sanctioned across 100 cities. The programme succeeded in improving urban infrastructure at an unprecedented scale.

But it did not measure whether cities were becoming cooler or hotter.

A look at the highest maximum temperatures in the following Indian cities since March this year should be a dead giveaway: Delhi 45.5°C, Ahmedabad 44°C, Pune 43.2°C, Hyderabad 42.8°C, Chennai 40.3°C, Mumbai 40.0°C, Kolkata 40°C, and Bengaluru around 34°C.

According to Mathur, the Smart Cities Mission has helped improve urban infrastructure and service delivery. The persistence of extreme heat, however, indicates that efficiency and digitisation alone are not sufficient measures of urban performance.

Roads, public spaces, transport upgrades and digital infrastructure are often delivered as independent components, each meeting its own technical and financial benchmarks. What is missing is a final layer of integration that tests how these elements work together in real urban conditions.

“A truly smart planning framework would treat active redevelopment zones as live prototype neighbourhoods. Technology can help design cities by managing water, energy, and natural shading systems; it can allow our neighbourhoods to function as self-sustaining and naturally cooled environments,” she said.

Building Cooler Cities

According to Mathur, a more workable direction is to move away from dispersed expansion towards more compact, mixed-use urban structures – residential, commercial, cultural, and institutional spaces that exist together in a single building or neighbourhood. “This is not about density in itself, but about how density is organised,” she said.

The GCA report suggests using hollow clay bricks, hollow concrete blocks, or aerated concrete blocks as these store less heat than thick clay.

On building design, it said, “The orientation of walls and windows that correspond with the sun’s direction and wind flow patterns can control the rate at which a building gains heat and room temperatures increase. In hot and dry regions, more compact building shapes can reduce heat absorbed by a building’s walls and roof.”

Jain believes that thermal performance of external surfaces should become a mandatory disclosure in building approvals. Public infrastructure procurement needs to stop defaulting to the cheapest-per-unit-cost, and indigenous natural stone should get a formal place in the green material palette for public projects.

“If you're developing a commercial project with a 10,000 sq ft plaza, you should have to demonstrate that the materials you've chosen meet a minimum solar reflectance index. This exists in some US and European codes. There's no reason India can't adapt it,” he said.

He said when the Central Public Works Department (CPWD) or a municipal corporation specifies materials for a footpath or a public square, the tender should factor in lifecycle thermal cost — how much additional cooling load is created in surrounding buildings and how much does the surface temperature deviate from ambient.

“I’d like to see indigenous natural stone get a formal place in the green material palette for public projects. We export Rajasthani sandstone to European streetscaping projects because they understand its thermal and aesthetic value,” Jain said.

Natural stones, particularly lighter-coloured varieties like limestone or sandstone have significantly lower heat absorption compared to concrete or asphalt. They don’t retain heat the way dark surfaces do, and release what they absorb more quickly once the sun goes down.

What Other Countries Are Doing

Global warming is a reality. According to the World Meteorological Organisation, at least 95% of Europe experienced above-average annual temperatures in 2025. A record three-week heatwave caused temperatures near and within the Arctic Circle to exceed 30°C last year, says its 2026 report. 

Countries are redesigning to be heat-resilient.

Paris has started the “OASIS” programme to transform schoolyards into green spaces accessible to vulnerable groups. Amsterdam and Vienna are combining water infrastructure with green spaces to create cooler urban environments.

In Asia, Singapore has introduced mandatory greenery on buildings, shaded pedestrian networks, wind corridors, and heat-sensitive building regulations. China’s Sponge City programme uses wetlands, permeable pavements, green roofs, and water-retention landscapes to lower urban temperatures.

Cities like Los Angeles and Phoenix in the US have been deploying reflective roofs, cool pavements, and heat-mapping systems to identify and cool the hottest neighbourhoods.

India has largely responded through Heat Action Plans, a Cooling Action Plan, early-warning systems, public advisories, and limited cool-roof and urban greening initiatives. But unless heat resilience is built into city planning, people in urban areas will continue to face the heat.