Passive cooling and other innovations can play a critical role in lowering air conditioner energy use during heat waves, experts say—but barriers remain for some communities to gain access to these cooling solutions.
“Running an air conditioner is just trying to solve a problem that it is also worsening,” building scientist Alexandra Rampel told the Washington Post. AC units account for 6% of annual U.S. electricity use, and currently emit 117 million tonnes CO2 per year—an amount only expected to increase as the climate warms. That has experts looking for ways to reduce the energy it takes to keep living space cool.
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Rampel is exploring ways to maintain low temperatures through passive cooling methods, such as the strategic use of shade, ventilation, and certain building materials. “On a warming planet, passive cooling can help protect people without access to air conditioning and lighten the load on the electrical grid from those who do,” explains the Post.
Alternatively—or maybe concurrently—the air conditioning industry is pursuing energy conservation through innovative technologies. “Whether it’s reducing the energy demands of air conditioning units, installing heat pumps that replace traditional AC and can cool the air as well as warm it, or offering ‘smart’ thermostats that save energy by automatically adjusting temperatures and fans to a homeowner’s preferred comfort levels, it’s clear we’ll need a multi-pronged approach,” writes the Toronto Star.
That approach so far includes contributions from private companies as well as support from Canada’s federal government. One Toronto-based company has become a leader in smart thermostats that “calibrate a building’s heating and cooling based on occupancy and variable electricity prices,” the Star says. By controlling temperatures to avoid AC use at peak demand, these thermostats can cut energy bills by up to 26%. Other innovations, like heat pumps and membranes to improve AC efficiency, are also promising.
Ottawa is offering subsidies toward home retrofits for some of the more expensive options, and some utilities have rebates for customers who install energy efficient cooling technologies.
But despite advancing knowledge in cooling solutions, “the problem of deadly temperatures is too big to be addressed person by person, home by home,” says the Post. Larger problems, like the urban heat island (UHI) effect, can undermine individual efforts to control indoor building temperatures.
Like passive cooling, UHIs arise from design factors—but at a much larger scale. At the municipal level, taller buildings, narrower urban “canyons”, less plant cover, more paved surfaces, and more waste heat from human activities can increase mid-day temperatures. As one example, the Post notes points to some inner-city areas of Phoenix, Arizona, where temperatures can be more than 5°C hotter than in parts of the city that have less of these heat-trapping features.
The UHI effect is also most likely to affect low-income communities of colour, where people are more likely to live in neighbourhoods with lots of paved areas, sparse vegetation, and less access to air conditioning. And, due to historic redlining, there are few building regulations in place that could mitigate the effects, such as summer insulation, or windows that can open.
“We really need to be intervening with buildings and neighbourhoods to make them more survivable,” Rempel told the Post.
