- Studies find that tin and cement roofs significantly increase indoor heat stress in rural households, posing serious health risks.
- Structural solutions such as better ventilation, tiled or insulated roofs, and vernacular materials such as straw and mud can effectively reduce indoor temperatures.
- Village-level, locally-informed heat action plans — as opposed to urban-focused models — are essential to protect rural communities from worsening heat stress.
India is breaking new records in summer heat each year, with some of the hottest days in its history now becoming an annual norm. As this trend intensifies, the cumulative impact of repeated heat stress on human health emerges as a critical concern. Recognising this is essential for designing effective, forward-looking heat action plans that can protect vulnerable populations in the years to come.
A new study from Maharashtra’s Wardha district examines the link between rural housing and heat stress, revealing that rural homes are becoming dangerously hot — an often overlooked issue in policy discussions. Conducted across 700 households and 2,672 individuals (54% men, 46% women), the study measured indoor temperature, humidity, and dew point.
The findings are stark: tin-roofed homes, which house 45% of the sample, recorded peak indoor temperatures of up to 40 °C, while cement (RCC) structures averaged 38.5 °C. This makes residents of tin-roofed homes significantly more vulnerable to heat exposure than those in cement or tiled-roof dwellings.
More significantly, 82% of residents reported experiencing at least one heat-related symptom — ranging from fatigue, excessive sweating, and intense thirst to more severe effects such as fainting, paranoia, and hallucinations.
Houses as heat traps
Premsagar Tasgaonkar, lead author of the study and a PhD student at the Tata Institute of Social Sciences (TISS), Mumbai, told Mongabay India that tin-roofed structures tend to become extremely hot during the day. However, they cool down at night bringing some respite to residents. In contrast, cement-roofed (RCC) houses trap heat and retain it through the night, disrupting residents’ ability to sleep. Tiled or traditional straw-roofed houses offer better insulation against heat, but the study found that only 2.1% of participants reported living in straw-roofed homes.
Tasgaonkar, who is working as a Research Associate at W-CReS (WOTR Centre for Resilience Studies), Pune, also observed a growing preference among residents to build “pukka” or RCC homes, as these are perceived to signal higher socio-economic status. “However, people are not paying attention to critical aspects like cross-ventilation or window placement, which traditional structures — such as tiled or even tin-roofed houses — often have,” he notes.
A 2021 study from West Bengal that assessed indoor heat stress in two contrasting settings — 123 slum dwellings in Kolkata and 101 rural homes — found similarly alarming results. Researchers monitored temperature, humidity, and Heat Stress Index (HSI) every 10 minutes over 24 hours during the summer of 2019, comparing indoor data with concurrent outdoor readings.
Given Kolkata’s high heat and humidity, the study also turned its lens on wet bulb temperature — the critical upper threshold of human heat tolerance — particularly among the elderly, the target demographic. “We found three to four-hour periods during the day when indoor conditions in slum homes reached the threshold of heat tolerance for elderly people,” says lead author Charles Weitz from the Department of Anthropology, Temple University, Philadelphia. “A substantial portion of Kolkata’s slum population — about one-third of all dwellings, by some estimates — falls into this category. So you have a huge number of people suffering through intolerable summer heat.”
The study found that some homes were significantly hotter than others, depending on factors such as wall materials, room size, and the number of occupants. “More people in a room meant significantly higher indoor temperatures,” notes Weitz. “Units with just one or two residents had notably lower temperatures than those with multiple occupants.”
Urban slums sear in hot sun
Niyati Shah, a Fulbright-Nehru student researcher studying indoor heat stress in Bengaluru, observes that the urban heat island effect worsens indoor heat conditions for urban slum dwellers. “Cities like Bengaluru, with numerous tech parks, high-rises, and dense concrete residential blocks, intensify the urban heat island effect,” she explains. “Many migrant communities live next to high-rises. They disproportionately experience heat stress because these concrete buildings accentuate the heat island effect,” she says.
These studies reveal that women — especially pregnant women — and, in some cases, children and the elderly are disproportionately affected by indoor heat stress, as they tend to spend much more time indoors than men. Certain behaviours seem to offer marginal relief, such as seeking shade, wearing light and loose clothing, and staying hydrated. However, both studies also highlight the importance of structural changes, such as improving ventilation, using tiled roofing, or painting roofs white to deflect sunlight.
Tasgaonkar has observed other coping mechanisms as well. “In RCC homes, people wet the floor or roof at night to reduce the temperature. Some place large, wet jute sacks on the RCC roof to cool it. Locally made desert coolers are also popular, but they require a lot of water.” Sleeping outdoors or using agricultural byproducts like hay as insulation on roofs are other strategies employed in Wardha and nearby hot regions. “Using hay on the tiles can lower indoor temperatures by 4-6°C. It’s a free and widely available solution. Some houses also have an insulation gap between the roof and walls, which significantly improves airflow,” he adds.
The studies conclude that indoor heat in rural areas poses a serious health hazard, causing significant discomfort and morbidity. Structural changes to homes — particularly roof type — are key to reducing heat exposure, as tin roofs present greater risk. Recommendations include using vernacular materials such as thatched roofs and mud walls, adopting cool roof techniques like high-albedo coatings and insulation, and enacting housing policies tailored to low-income households. Crucially, there is a need for localised heat action plans developed and implemented with the involvement of local stakeholders. Shifting from urban-centric approaches to village-level heat strategies may better protect vulnerable rural communities.
Read more: When heat rises, incomes fall for the informal workforce
Banner image: As summer heat intensifies each year, studies find that tin and cement roofs increase indoor heat stress in rural households. Image by Premsagar Tasgaonkar.
