Mitigating the Impact of Heat Waves in Urban India

South Asia stands at the frontline of the global heat crisis. Climate change is driving longer, more frequent, and more intense heatwaves across the region. The IPCC Sixth Assessment Report (2023) identifies South Asia as one of the most heat-vulnerable regions in the world. India faces escalating urban heat stress. The summer of 2024 ranked among the hottest on record, with Delhi surpassing 46°C and the Indo-Gangetic Plain sweltering under prolonged heatwave conditions.

In Indian cities, the impact of this heat is uneven. Poorly planned urban areas trap heat due to the Urban Heat Island (UHI) effect, intensified by concrete, asphalt, and metal roofing that absorb and radiate solar energy. In informal settlements, indoor temperatures can exceed outdoor temperatures by 8–10°C, posing severe health risks for children, the elderly, and women. Recognising the growing danger, the National Disaster Management Authority (NDMA) in India has formally declared heatwaves as a national disaster – an acknowledgement of the urgent need for adaptive, community-centred mitigation strategies.

As world leaders convene at the Conference of the Parties (COP) 30 in Brazil, living in a warmer world and the adaptation mechanisms required are key discussion points. Sustainable Environment and Ecological Development Society (SEEDS) has pioneered a community-centred approach to heat resilience, particularly in the Delhi National Capital Region, that is relevant to the Global South.  The significance of these efforts was highlighted recently at the G20 Ministerial Declaration on Disaster Risk Reduction, which endorsed the adoption of ‘Resilience of All’.

Heat Impact on Urban Populations

The Global South is experiencing rapid urbanisation, dense construction, and the loss of green spaces, turning its cities into heat traps. According to the Indian Meteorological Department (IMD), the number of heatwave days in India has more than doubled since 1980. Cities such as Delhi, Ahmedabad, and Hyderabad now endure longer and more intense heat events. Yet, heat does not affect all residents equally – the poor, migrants, and those in informal settlements bear the brunt.

Nearly 65 million Indians (17% of the urban population) live in slums (Census 2011). These neighbourhoods are marked by tin or asbestos roofs, poor ventilation, overcrowding, and little access to shade or open spaces. During peak heat, indoor temperatures often exceed 45°C, even at night. Families living in single-room homes suffer dehydration, sleep deprivation, and heat exhaustion. The absence of reliable electricity or water worsens the crisis, while storing water in plastic containers further increases indoor heat. Rising electricity and healthcare expenses, coupled with declining productivity, deepen economic hardship.

Migrant workers – employed in construction, street vending, sanitation, and delivery services – face extreme exposure to outdoor heat. Long hours under direct sunlight, often without rest or shade, lead to heat exhaustion, dehydration, and sometimes fatal heatstroke. The NDMA (2022) estimates that extreme heat can reduce labour productivity by 15–20%, especially in informal sectors. For daily wage earners, lost workdays mean immediate income loss, pushing families into deeper vulnerability.

Prolonged heat exposure has well-documented physiological consequences: Heat exhaustion, dehydration, and heatstroke (core body temperature >40°C). Exacerbation of cardiovascular and respiratory diseases due to higher ozone and particulate matter. Declines in mental health, sleep quality, and overall productivity.

The World Health Organisation (WHO) identifies urban poor communities as climate-vulnerable populations needing priority adaptation interventions.

Strategies for Mitigating Urban Heat

Reducing the impact of urban heat requires both immediate relief and long-term structural action. Effective strategies span urban design, building innovation, and policy planning.

Urban Design and Green Infrastructure:  These include expanding urban greenery: Parks, roadside trees, and green belts provide shading and cooling through evapotranspiration, lowering local air temperatures by several degrees. Restoring waterbodies: Lakes, ponds, and wetlands act as natural coolants through evaporation and convection, moderating urban microclimates.

Reflective and permeable surfaces: Light-coloured pavements and porous materials reduce surface heat absorption and allow rainwater infiltration.

Cities like Ahmedabad, Chennai, and Pune are integrating ‘blue-green infrastructure’ into urban plans – linking parks and lakes to form interconnected cooling corridors.

Building-Level Interventions: Cool roofs: Low-cost methods such as lime wash, reflective coatings, bamboo shading, or rooftop gardens can lower roof surface temperatures by 15–20°C and indoor temperatures by 8–10°C.

Passive design: Features like roof insulation, shaded verandas, and cross-ventilation improve thermal comfort naturally.

Energy-efficient construction: Incorporating reflective materials and green building codes into affordable housing programs like PMAY-Urban can significantly reduce urban heat exposure.

Heat Action Plans and Early Warning Systems: Cities like Ahmedabad, Delhi, and Hyderabad have introduced Heat Action Plans (HAPs) that integrate early warning systems, community outreach, and inter-agency coordination. Policies promoting rest breaks, shaded shelters, and hydration facilities for outdoor workers are essential, alongside medical preparedness for heat-related illnesses.

On the ground, initiatives are also focusing on making these strategies more inclusive and context-specific. For instance, SEEDS’ interventions combine awareness, design innovation, and infrastructure adaptation to reduce heat exposure among low-income groups.

Starting from community-led awareness, an Under the Umbrella campaign since 2024 supports vulnerable communities during extreme heat. It raises awareness on heat risk, promotes simple cooling methods, and links residents to safe shelters. In Kishan Kunj, an informal settlement in East Delhi, we introduced cool roof treatments using reflective materials and insulation.

Through community networks, heat alerts and educational materials are disseminated in local languages, ensuring households receive timely warnings. Collaboration with community health workers, NGOs, and local leaders ensures consistent messaging on hydration, rest, and protection for children and the elderly.

Further, working with the community, we implemented lime-based cool roof solutions in low-income settlements of northwest Delhi, reducing indoor heat at minimal cost. The organisation also employs AI and GIS tools to map building-level heat risk, using satellite and land-surface temperature data to identify the most vulnerable homes. These insights help target interventions effectively and build evidence for policy replication.

Promoting ‘living laboratories’ where communities co-design and test heat mitigation solutions in areas such as Kishan Kunj, this approach led to shaded streets, insulated walls and roofs, refurbished drinking water facilities, and worker shelters. These interventions not only reduced indoor heat but also enhanced overall liveability, offering a replicable model for other urban areas. At a city level, we recognise the role of urban waterbodies in cooling microclimates. We have restored one lake in Delhi and three in Gurugram, where dense construction had degraded natural cooling systems. These restored sites now help moderate local temperatures and benefit thousands of nearby residents.

Key Insights from Heat Mitigation Exploration

• Built form matters: Tin-roofed, densely packed houses amplify heat stress, underscoring the importance of design-focused interventions.
• Community agency drives success: Once communities experience tangible benefits, they sustain and replicate interventions independently.
• Scaling challenges remain: Pilots demonstrate impact, but large-scale adoption needs policy alignment, urban planning integration, and innovative financing.
• Data enables precision: AI-based heat mapping identifies hotspots and ensures interventions reach those most in need.
• Holistic resilience: Heat interacts with housing quality, socio-economic status, and health – requiring solutions that link infrastructure, awareness, and early warning systems.

To build truly heat-resilient cities, India must integrate these approaches into urban planning, housing policy, and climate adaptation strategies – transforming today’s pilots into tomorrow’s urban standards.

Sustainable, inclusive, and climate-smart design is not just about keeping cities cool – it’s about keeping communities alive.

The author is the Director of the Built Environment, Sustainable Environment and Ecological Development Society (SEEDS).