As both incomes and average temperatures increase worldwide, so does air-conditioning use. In a paper published in Nature Sustainability last December, Berkeley researchers warn that global demand for cooling could drive huge increases in electricity usage.
Using daily temperature data from more than 14,500 weather stations, the group ranked 1,692 cities and 219 countries by “total cooling degree day (CDD) exposure,” a common metric for cooling demand. Their results pinpoint eight countries with higher CDD exposure than the United States: India, Indonesia, Brazil, China, Pakistan, Bangladesh, Nigeria, and the Philippines.
Currently, the U.S. leads in electricity use for cooling. Some 400 terawatt-hours of electricity go to U.S. air-conditioning annually, representing 1.5 percent of all electricity consumption worldwide. But as middle classes in developing countries expand, significantly more people are expected to buy air conditioners.
Two factors that influence CDD exposure are population size and temperature. Although the population of the Philippines is just one-third that of the U.S., for example, the island nation’s CDD is four times as high, owing to its hotter climate. Populous India leads with 28 percent of global CDD exposure, and Mumbai alone has a CDD exposure equivalent to 25 percent of the United States’.
Virtually everywhere on the planet is hotter than just two decades ago. Along a horizontal band through northern Africa, the Middle East, and southern Asia, vast areas are exposed to 3,000-plus and even 4,000-plus CDDs annually; by comparison, sweltering Phoenix, Arizona, has 2,700 CDDs.
“Increasing cooling demand will likely cause significant electricity-usage spikes worldwide,” said co-author Léopold Biardeau, a PhD student in agricultural and resource economics. “But adaptation strategies may help mitigate the need for air-conditioning. For instance, architecture can play a critical part in controlling temperatures inside buildings.”
– Adapted from a Haas Energy Institute Blog by study co-author Lucas Davis