MORE EXTREME, less liveable heat is inevitable for India. Last year was the hottest ever recorded there, with some places seeing temperatures in excess of 50°C. Ten of the country’s 15 warmest years on record have occurred in the past decade and a half. Extreme heat will sap productivity, slow economic growth, lower wages and raise health-care costs. An India that cannot stay cool cannot get rich.

Air-conditioning, a century-old technology, offers a solution. Indians who can afford it are buying it in droves. Annual sales more than doubled in the five years to 2024, to 14m units. Angshuman Bhattacharya of EY Parthenon, a consultancy, says 2024 was “one of the most blockbuster years, and most companies ran out of stocks”. Samsung, a manufacturer, expects sales to rise by another 20-25% this year.

India is treading a well-worn path. As hot countries get richer, air-conditioners, once luxuries, become necessities. But in India extreme heat and high levels of humidity that make fans less effective have made them essential long before average incomes have risen to a level where they are widely affordable. Just 10% of households boasted an air-conditioner in 2023.

There are various ways to make them cheaper. Manufacturers want the government to lower sales tax, now at the highest rate, 28%. The Indian government has put in place incentives for makers of white goods in the hope that it will both lower prices and create jobs.

Inevitably, air-conditioner penetration in India will soar. That will cause problems of its own. The biggest is a tremendous surge in energy demand. During a heatwave last May peak demand in the afternoon crossed 250 gigawatts, with about a fifth of that accounted for by air-conditioners. The energy they consume could lead to power shortages. Moreover, air-conditioners themselves cause their immediate environment to get hotter, and the hydrofluorocarbons (HFCs) they use as coolants exacerbate climate change.

What to do? One answer is to encourage simple tweaks to homes and buildings, such as painting roofs white to better reflect heat. Changing building codes to promote insulation, cross-ventilation and vents and ensuring shade from trees, would also help. But such policies’ effects will take decades. Much more urgent is to raise minimum energy-efficiency standards for air-conditioners.

Most appliances sold in India come with labels that rate their efficiency from one to five stars. Three-star air-conditioners account for over 60% of sales. Largely because of the high up-front cost, five-stars make up under a quarter. Yet India’s standards are so low that the vast majority of units bought would not be eligible for sale in China, says Nikit Abhyankar of the India Energy and Climate Centre at the University of California in Berkeley. New standards coming into effect next year are only somewhat higher. He proposes setting minimum standards at the level of the most efficient models available in India today, with similar ratchets in 2030 and 2033. This could lower peak energy demand from air-conditioners by a third.

This need not cause prices to spike. Mr Abhyankar points out that other countries’ experience shows that “efficiency revisions have always been accompanied by price reductions”. In Japan efficiency nearly doubled in the 25 years to 2015 while inflation-adjusted prices dropped by four-fifths.

India has already ratified a global treaty to phase out 85% of HFCs by 2047. Radhika Khosla of the Oxford India Centre for Sustainable Development calculates that, by setting higher efficiency standards, promoting “passive” cooling in building codes and retrofitting, and speeding up the reduction of HFCs, global emissions from cooling could fall by 66%, with India playing a big part.

The government is weighing its options. One is to offer buybacks for older units to encourage the switch to higher-rated ones. Another is to try to replicate its success in bulk-buying and selling energy-effiicent LED tubelights and bulbs at low cost. Subsidies and higher standards are not off the table either. It has a tricky task: ensuring more Indians have access to cooling without the surging emissions that hundreds of millions of new air-conditioners would produce. Yet it must do both.