Study finds Chennai tops in AC usage among 7 cities, raises concerns over refrigerant emissions

The most common type of refrigerant used in ACs, known as HFC-32, has a global warming potential that is 675 times higher than carbon dioxide.
| Photo Credit: S.R. RAGHUNATHAN

Air conditioners (ACs), an appliance increasingly seen as essential in the face of rising temperatures, are themselves becoming a major contributor to the climate crisis.

A new survey of 3,100 respondents from seven metro cities by the International Forum for Environment, Sustainability and Technology (iFOREST) shows that AC usage in Chennai is the most intense among the surveyed cities, which includes Delhi, Mumbai, Kolkata, Ahmedabad, Pune, and Jaipur.

Households run their units for an average of 4.4 hours a day as the city faces long, humid summers. Nearly 23% of households own more than two ACs, nearly double the national average. Yet, awareness about the environmental impact of refrigerants remains low. Around 64% of respondents in Chennai say they are unaware of climate-friendly refrigerant options, and only 16% expressed willingness to switch to greener alternatives if they were affordable — the lowest among all surveyed cities.

The study states that Chennai has the highest rate of refrigerant refilling among the seven cities, with more than half of all residential air-conditioning units undergoing refrigerant top-ups every year. This figure is well above the national average of 41%. Ideally, a properly functioning AC should only need a refill once in five years, but in India, frequent refilling has become the norm, often without fixing the actual leak that caused the gas loss in the first place.

This practice has both financial and environmental costs, the study notes. Each refill costs households in Chennai an average of ₹2,300, the highest in the country, and contributes to the release of powerful greenhouse gases.

Refrigerants used in ACs are not supposed to escape into the atmosphere, but when leaks are not repaired and the gas is simply topped up, much of it ends up leaking again. In many cases, there’s no equipment used to capture or recycle the old refrigerant, so it is often vented directly into the air. These refrigerants, though invisible, are extremely potent. The most common type, known as HFC-32, has a global warming potential that is 675 times higher than carbon dioxide. 

When multiplied across thousands of households, the impact becomes huge. iFOREST estimates that refrigerant leakage alone contributed to 52 million tonnes of CO₂-equivalent emissions in 2024 — comparable to the annual emissions of millions of cars. The report also found that 73% of AC servicing complaints in Chennai were related to unnecessary refrigerant refilling. This points to a lack of technician training and poor servicing standards.

While the India Cooling Action Plan outlines broad goals, including a 25%–30% reduction in refrigerant demand by 2037–38, the iFOREST study notes that enforceable regulations are still lacking. Similarly, rules that require refrigerant recovery from discarded ACs exist on paper under the 2023 E-Waste Rules, but implementation remains weak.

iFOREST recommends that India adopt a robust lifecycle refrigerant management (LRM) framework, which must include mandatory recovery and recycling of refrigerants, technician training, and extended producer responsibility for AC manufacturers.

Published – September 16, 2025 09:08 pm IST

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