Beat the Heat Efficiently

By Eduardo Garcia | July 3, 2019  The New York Times, Climate Fwd: Newsletter

A heat wave scorched Europe through the weekend and Americans are facing what’s predicted to be a very hot couple of months. Last summer ranked as the fourth-hotteston record for the lower 48 states, and this year’s temperatures are expected to be above average in most of the country.

So, how do you win the battle against summer heat in a sustainable way?

When it comes to cooling your home, you basically have three options: open your windows, use fans or turn on the air conditioning.
Natural ventilation is the most sustainable choice, hands down, because it doesn’t use power. It’s an especially good option in coastal areas, where temperatures often drop at night, but it won’t work for everyone.
When temperatures stay high and there’s little wind, fans are the next-most-sustainable choice because they bring relief while using relatively little electricity.
“Ceiling fans are very effective because they help a room feel colder while using a lot less energy than a central air-conditioner,” said Lauren Urbanek, who works on energy policy at the Natural Resources Defense Council.
Box fans are a good option, too. They typically consume less energy than a 100-watt light bulb.
Air-conditioners are the most popular way to cool a house — nearly 90 percent of homes in the United States have them. But, they are also the most damaging to the environment because they consume a lot of power and discharge hot air that can raise outside temperatures, a phenomenon known as the heat-island effect. That’s especially a problem in cities.
“They exacerbate climate change by increasing carbon dioxide emissions from power plants as well as some direct leakage of HFCs,” said David Abel, a postdoctoral researcher at the University of Wisconsin-Madison. He was referring to hydrofluorocarbons, chemical coolants that are also powerful greenhouse gases.
The human and environmental impacts of air-conditioners are mixed. A study in 2016 that focused on the immediate cooling benefits found that air-conditioners had cut premature deaths on hot days in the United States by 75 percent since 1960. On the other hand, Dr. Abel was the lead author of separate study, in 2018, that looked at the air pollution aspect. That research concluded that air-conditioners could cause hundreds of deaths in the Eastern United States by midcentury because of air pollution.
So, air-conditioners may be both a blessing and a curse. To use them in a sustainable way, experts recommend that you set them at a relatively high temperature (78 degrees Fahrenheit, or about 25 Celsius) when you’re at home, make sure that your house is properly insulated so that the cold air doesn’t escape, and use them in tandem with a fans to increase their cooling efficiency.
If you plan to be away from home for at least a couple of hours, raise the temperature to 85 Fahrenheit, or roughly 29 Celsius, or just shut your air-conditioners off. If you have a programmable system or a thermostat app, you can set it up to resume cooling before you return.
One last thing: Bear in mind that heat largely comes into your home via sunlight, so using curtains or shades when the sun is high will help you win the battle.

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