Warming Has Made Air Conditioning a 'Huge Growth Industry.' Untangling That Dynamic Presents a Major Efficiency Challenge

During the summer months, air conditioning for most U.S. households is a thoughtless -- if expensive -- indulgence, whirring innocently in the background from vents and window ledges. However, it brings with it an elaborate, international puzzle that utilities, governments, industry and everyday consumers are responsible for both creating and untangling. 

Air conditioning amounts to roughly 10 percent of global electricity consumption, though it also contributes additional emissions via the refrigerants -- potent greenhouse gases like hydrofluorocarbons, currently the subject of proposed rule-making by the Environmental Protection Agency -- it leaks. 

And in the United States, AC is nearly ubiquitous. A July 16-18 poll from Morning Consult found that 90 percent of U.S. adults have air conditioning, a number consistent with the findings of the International Energy Agency’s seminal 2018 “Future of Cooling” report. An additional 3 percent said they do not have AC but intend to install it within the next year.

Air conditioning is especially prevalent in the South (95 percent) and Midwest (91 percent), where heat and humidity regularly reach uncomfortable levels. In the West -- a region that is generally more temperate, especially along the coast -- 80 percent say they have AC. After the June heat wave in the Pacific Northwest, a preliminary analysis found that a lack of AC was a major factor in the over 50 heat-related deaths in Oregon’s Multnomah County. 

But on a global scale, only about a quarter of people living in a region that would merit cooling have access to AC, according to Iain Campbell, a senior fellow working on carbon-free buildings at the clean energy think tank RMI. Much of the remaining 75 percent, he added, will be able to afford an AC system in the not-too-distant future.

There’s a tipping point, Campbell said, where the level of heat discomfort a person is willing to stand hits its maximum; while 10 days of discomfort per year was once doable somewhere like the Pacific Northwest, climate change has served as a multiplier. As the planet warms -- and people have more disposable income to put toward cooling -- more communities will hit this tipping point.

“It’s a huge growth industry because our planet is warming,” Campbell said. While air conditioning has essentially saturated the U.S. market, this is not the case in many warmer climates, such as Brazil (where 16 percent had access to AC as of 2018) and India (5 percent as of 2018), according to IEA. Meanwhile, as China rapidly develops, it has increased its energy demand for space cooling in buildings since 2000 at a rate of 13 percent per year, per a 2019 IEA report.

Extreme heat events are sure to accelerate this process. In the Morning Consult survey, 63 percent of U.S. adults said the region where they live has experienced a heat wave -- ​​defined as a period of multiple days of abnormally high temperatures -- so far in 2021. And 27 percent said they have been asked by their electricity provider or local authorities this year to conserve electricity or cope with rolling blackouts. In the western part of the country, the share is 47 percent. 

“The grid is at its limits on the hottest days of the year, and that’s because cooling represents such a large part of the peak demand,” Campbell said. Cooling can make up as much as 60 percent of the peak load in places with high AC unit penetration on the hottest days of the year, he added, pointing to IEA data on the subject.

Those hot days are becoming more frequent just as the grid transitions to a mix of more renewable resources, causing variability in supply. The current rate of solar deployment is not keeping pace with the demand air conditioners add to the grid when they operate at full capacity. 

Brian Reil, a spokesperson for the Edison Electric Institute, which represents all U.S. investor-owned electric companies, said the industry is "making appropriate investments to manage peak demand" and boost grid resilience through storage and clean energy technologies, though it is an iterative process, as illustrated by high-profile outages in Texas and the Pacific Northwest that have come as a result of a supply-and-demand mismatch amid extreme temperatures.

Fitting air conditioning into this dynamic has created an efficiency conundrum that Campbell calls “absurd”: The vast majority of people, he said, purchase AC units at the minimum-required efficiency levels because they are both cheap and available. Blind to anything but the sticker price, they end up paying more in electricity bills for the privilege of a cheap system. In turn, their utility has to add grid capacity to cope with the excess energy consumption of the inefficient units. 

RMI’s Global Cooling Prize project zeroed in on technologies that could deliver cooling at significantly lower emissions rates than those currently available, providing ammunition to those pushing for higher efficiency standards and to get these more efficient models to market as the planet warms.

The Association of Home Appliance Manufacturers did not respond to a request for comment on U.S. standards by the time of publication.

Most survey respondents said they have central air conditioning (65 percent), while 25 percent have a window unit, 4 percent have a portable unit and another 4 percent have something else. This “something else” could include high-efficiency options such as reverse cycle heat pumps. 

Suburban homes are least likely to rely on window units (19 percent), as 73 percent use central AC. Both urban and rural respondents rely on window units at similar rates: 33 percent and 31 percent, respectively. 

The efficiency of an AC unit depends largely on the temperature to which it is set; each degree of cooling substantially increases a system’s overall electricity use. The survey found that half of respondents set their systems during the day to below 73 degrees, with 13 percent of those selecting 68 degrees or lower. Forty percent selected options between 73 and 78 degrees, while 11 percent selected 79 degrees or higher. 

But average temperatures dipped somewhat overnight, with 55 percent setting their thermostats to lower than 73 degrees, and 16 percent of those selecting 68 degrees or lower.

The poll, which surveyed 2,199 U.S. adults, including 1,968 with air conditioning in their homes, has a margin of error of 2 percentage points.