With warmer weather comes more reliance on air conditioning.
Here & Now‘s Jeremy Hobson speaks with Glenn Hourahan and Todd Washam of the Air Conditioning Contractors of America (@accausa) about the state of the industry and some consumer tips to keep cool without wasting energy.
For starters: How does an air conditioner work?
“Basically what you’re doing is you’re moving the heat from the inside of the home to the outside of the home, and you’re doing that by change of state of a fluid — the refrigerant,” Hourahan says. “And so it changes from a gaseous to a liquid state. And when it does that, it removes a lot of [British thermal units] of energy with it, so taking the air that blows over the indoor coil, which then moves that coolness throughout the house.”
“ACCA recommends setting the thermostat at 75 degrees Fahrenheit for summer cooling and 68 degrees Fahrenheit for winter heating,” Hourahan says. “Obviously, people are going to set it at the temperatures they’re most comfortable at. In my particular case, I am very happy at 78 degrees for summer cooling when the humidity is under 50 percent. So if you control humidity you can set your thermostat up higher.”
“[Today’s have] quite a bit more electronics and circuit boards, and controls on logic, all done to make the equipment operate more efficiently, provide better indoor air comfort,” Hourahan says. “Some other changes are, 20 years ago, everybody had single-speed equipment — it was either on or it was off. Today there’s variable-speed equipment and multiple-speed equipment, depending how hot or cold it may be outside.
“The minimum SEER, which is seasonal energy efficiency ratio, the minimum SEER available today that by law you can buy is 13 in some places, but most of the country is 14. [SEER is] a ratio, it’s sort of like your miles per gallon. So the higher the number, the more efficient the box is operating at under laboratory conditions. And so there’s equipment out there that does double what the minimum is. But it becomes much more expensive as you move on.”
While equipment has gotten steadily more efficient, “half of the systems in the U.S. are using more energy than what the label says on them,” Washam says.
“The EPA estimates that half of all HVAC systems in the U.S. are not installed according to the manufacturer’s recommended installation standards. So you have a 14 SEER unit, and half of those units are operating at an eight to 10 SEER level.”
“Our message is that you can help address that issue by working with contractors and homeowners to ensure their HVAC systems are installed properly,” Washam says. “If they’re installed properly, you’re going to have 30 to 40 percent less energy being used in those systems. So it may not help with the exact peak demand that utility operators are looking for, but it will help on the overall use of the grid.”
“There’s a lot of parts in the country, Pacific Northwest, that air conditioning is really not a necessity, because they don’t have that many days that [it] gets very hot,” Hourahan says. “The Northeast part of America, same thing, they don’t have a very long summer period as well, and so fans may work for them.”
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