CSE report links higher cooling load to urban heat island effect and reduced night cooling

New Delhi’s electricity demand has surged during the monsoon months despite fewer heatwaves, driven by higher humidity and rising night-time temperatures, according to a new policy brief by the Centre for Science and Environment (CSE).

The report highlighted that in August 2025, peak power demand was 2 per cent higher compared with August 2024, even though rainfall was heavier this year. Nearly half the days in August 2025 (16 out of 31) recorded higher peak demand than the same days a year earlier. Researchers found that 67 per cent of Delhi’s daily peak electricity demand can be explained by variations in temperature and humidity, measured as the heat index.

The CSE study noted a shift in peak cooling demand to night hours, with the average demand now spiking at 11.09 p.m. compared to afternoon surges seen in earlier years. This trend is attributed to a 42 per cent reduction in night cooling compared to the 2001–2010 average, meaning that the drop in temperature from day to night has narrowed, worsening thermal discomfort.

The findings point to a deepening urban heat island effect, where built-up surfaces trap heat during the day and release it slowly at night, raising night-time temperatures. A 2024 study by the Indian Institute of Technology, Bhubaneswar found night-time warming in over 140 Indian cities to be nearly 60 per cent higher than in surrounding non-urban areas.

Researchers warned that worsening night-time heat not only drives cooling demand but also heightens health risks, especially for vulnerable urban populations, as cities grapple with climate stress and rising energy needs.