Union human resource development minister Prakash Javadekar has said he would ask manufacturers of air-conditioners to set the lowest target temperature at 24°C instead of the current 18°C, to conserve energy. Javadekar, who was environment minister earlier, said he had learnt that air-conditioners sold in the country currently have a fixed lowest minimum temperature of 18°C. “I find people keep their AC at 18 °C in their houses. I found out the reason. The air-conditioners do not allow the temperature to be lowered further,” Javadekar said today, addressing a conference on higher education in India. “If they could, they would have lowered it even further.” Javadekar said people can be comfortable at temperatures higher than 18°C. “I am going to write to AC manufacturers to make the minimum possible temperature 24°C,” he said. Air-conditioning engineers agree that most people would find themselves comfortable at room temperatures of about 24°C, although the degree of comfort depends on multiple factors, including relative humidity, the presence of ceiling fans, and even clothing. “Yes, this can be done, it would not be a major engineering challenge to set comfort temperatures at 24°C,” said Chandrasekaran Subramaniam, the Bangalore-based president-elect of the Indian Society of Heating Refrigerating and Air-Conditioning Engineers. “The remote (controls) used to set the temperatures could be programmed to stop at 24 °C,” he said. However, for air-conditioners that cool and heat, it may be necessary to set two temperatures – one for summer and one for winter, he said. Without two temperatures, air-conditioners would use up large amounts of energy to raise the temperatures to 24 °C during winter when outside temperatures are very cold. “For instance, if the ambient temperature outside is 7°C, it will take a lot of energy to heat a room to raise it to 24°C than a little lower, for instance, to 20°C,” Subramaniam said. Japan has been discussing codes for air-conditioners that would set low temperatures at about 27°C, he said. “They want people to use clothing appropriate to temperatures. People sometimes wear blazers and jackets and use ACs to lower temperatures.”

(Source: The Telegraph, Kolkata, July 30, 2017)