Tips for buying the right AC unit amid a record heat wave sweeping the US
Record-breaking heat is sweeping across the United States scorching 118 million Americans from coast to coast this week, leaving many to rely on air conditioning systems to cool homes, bedrooms and offices during the heat wave.
The mid-summer stretch of sun comes just weeks after a Fourth of July weekend heat wave that brought high temperatures to many parts of the country.
As Americans gear up for another week of potentially hazardous heat, ABC News spoke with experts about how to buy the right AC unit.
What are the differences in AC units?
Michael Brandemuehl, emeritus professor of civil, environmental, and architectural engineering at the University of Colorado Boulder, talked about the differences between a mini-split system, a window unit and a portable air conditioning.
He said window units, or in-room units, are best for bedrooms and living areas, but they're a "temporary" fix for the overwhelming heat.
These units are generally less expensive than mini-splits and are easily installed.
For a more permanent cooling option, Brandemuehl suggested a mini-split air conditioning system. Mini-splits are a two-part unit consisting of an outdoor compressor wired to a wall-mounted unit indoors.
"If you want an air conditioner that is going to last for longer, is going to actually serve a continuing need, a mini-split system actually really works well for many of the same spaces that a room air conditioner works," Brandemuehl said.
He added that mini-split systems tend to be more efficient than window or room air conditioners and can extend to larger spaces.
Arianna Coger, who tests air conditioners for Consumer Reports, said mini-splits come with a larger price tag than in-room or window AC units.
"You're going to spend a couple of thousand dollars upfront, but in the long run, you're going to save on energy efficiency," Coger said.
A simple portable air conditioner unit, one that plugs into a wall, is "a desperation move," according to Brandemuehl, who said portable units are "not a long-term solution." They are, however, generally cheaper and easier to install than mini-split and in-room options.
Central air is a more complex AC system that cools homes and buildings through a cooling network.
What is BTU and SEER?
BTU (British Thermal Unit) per hour and SEER (Seasonal Energy Efficiency Ratio) are ways to measure the power and efficiency of an air conditioning system.
BTUs per hour describe the rate at which a space is cooled, according to Brandemuehl.
"That is just the amount of cooling it can perform and how quickly it can change the temperature in the room," he added.
SEER stands for seasonal energy efficiency ratio, which measures a machine's efficiency. Brandemuehl said a SEER range is generally from low teens to 20s.
Oftentimes, air conditioning units will advertise their compatibility with a certain size of room.
According to Coger, a "large" room (500 to 600 square feet) requires around 10,000 or more BTU.
A "medium" room (250 to 400 square feet) would call for around 7,000 to 8,500 BTU and a "small room" (250 square feet or less) would need 6,500 BTU or less.
How to make sure you purchase an efficient AC unit?
Both Coger and Brandemuehl agreed that in order to make sure an AC unit is running as efficiently as possible, one must take into account the room's conditions.
Brandemuehl said AC units with variable speed compressors are able to decrease the power of the air conditioning dynamically, so as not to expend extra energy turning off and on to maintain a specific temperature through the day.
Having a unit with a variable speed compressor, or inverter drive, may allow consumers to more effectively navigate appropriate energy usage. Brandemul noted utility companies sometimes charge different energy pricing depending the time of day you are using the system.
Coger also suggested finding AC systems that use inverter technology.
"As you get closer to the set point, it begins using less and less energy while still cooling the room," she explained.
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