The world’s most populous country will have more than 1 billion air-conditioning units in operation by 2050, according to the International Energy Agency. NEW DELHI: Sheetal Kumari and her family used to go without an air conditioner until their home became unbearable during the summer months, when the average maximum temperature soars to nearly 40 degrees Celsius. The 21-year-old student lives in an urban slum on the outskirts of New Delhi, where homes are often built hastily in narrow spaces