India's Magic Temperature 24 degree celsius
In 2024, a record 14 million AC units were sold in India. By 2030, this figure will more than double.
India is the fastest-growing AC market in the world, and by 2050, we will most probably become the largest market
With cooling contributing around 25-30 per cent of the country’s peak energy load, the AC ends up taking much of the blame, despite only about 8-10 per cent of Indian households owning them.
India’s grid emits about 727 grams of CO₂ for every kilowatt-hour of electricity generated.
In June this year, Union power minister Manohar Lal Khattar proposed guidelines to limit the temperature range for ACs across the country — 20 to 28°C.
As per a 2018 estimate by the BEE, setting ACs at 24°C instead of 20°C could save about 20 billion units (kWh) of electricity annually, translating to 16-18 million tonnes of CO₂ if widely adopted.
It also ties directly to the India Cooling Action Plan (ICAP), which seeks to reduce overall cooling demand by 20-25 per cent by 2037-2038.
In 2020, the BEE (Bureau of Energy Efficiency) mandated a default thermostat setting for star-rated air conditioners: 24°C.
"We chose 24°C because it was technically viable and politically acceptable,” said Ajay Mathur, professor in the School of Public Policy at IIT Delhi and a former director general at BEE.
Manufacturers told BEE that at very low set-points (18-22°C), energy use rises sharply — roughly 6 per cent more per degree lowered. At mid-range (24-26°C), the change in energy use per degree is around 4-5 per cent, and at 27°C and beyond, about 3 per cent. By choosing 24°C, Mathur said, the BEE could meet the energy savings range of 5-6 per cent per degree.
The experts call it a "Thermal Comfort". it as “the condition of mind which expresses satisfaction with the surrounding thermal environment.”
“Actually, temperature and humidity both play a very important role in your thermal comfort.”
Crucially, though, most Indian thermal comfort studies don’t account for humidity.
India Model for Adaptive (thermal) Comfort, IMAC, considers humidity, air temperature, air velocity (wind speed) and the mean radiant temperature of room surfaces, while calculating thermal comfort.
The reason humidity matters is because in humid weather, the AC isn’t just cooling air to the set point, it’s also “working harder to remove moisture”. That extra effort keeps the compressor running longer, which pushes up electricity use and bills.
In many places — cinemas, hotels, restaurants and buses — ACs are run unnecessarily at very low temperatures, making people uncomfortable enough to use jackets or blankets indoors.”
Researchers are now focused on finding alternative paths to reduce the use of AC itself. One of the ways, could include better building design — from cross-ventilation to reflective roof coatings and cooling paints.
