A study conducted by Climate Trends, presented at the India Heat Summit 2026 in New Delhi, reveals alarming levels of indoor heat exposure in low- and middle-income households in Chennai, India. The research, which utilized high-resolution sensor data across 50 households from October 2025 to April 2026, found that indoor temperatures frequently exceed 32°C, with some households experiencing up to 5,800 hours of heat exposure, equivalent to 8 months. Notably, temperatures peak between 8 PM and 9 PM, as concrete structures release stored heat, causing indoor temperatures to remain above 34°C well into the night.

The study emphasizes the need for integrating indoor heat monitoring into urban Heat Action Plans, as current frameworks primarily focus on outdoor temperatures. Aarti Khosla, founder of Climate Trends, highlighted the urgent need for interventions, noting that even during cooler months, indoor temperatures rarely fell below 31°C. The disparity in cooling solutions is stark; while high-income households often have air conditioning, low-income households rely solely on ceiling fans, exacerbating heat exposure.

The summit featured discussions on the necessity of revising building codes to ensure thermal comfort for all, particularly those in informal housing structures. Experts stressed the importance of inclusive communication strategies to reach vulnerable populations, ensuring they receive timely weather forecasts and warnings. The findings underscore the pressing need for comprehensive policy changes to address the growing challenge of heat stress in urban India.