Looking to save on your energy bill? Give precooling a try

Precooling during warmer months can be an effective way to decrease your monthly energy bill. Customers enrolled in any of our three Saver Choice time-of-use plans can potentially save money by precooling their house during lower-cost, off-peak hours.

The basic idea is to chill your house before 3 p.m., so much so that your air conditioner runs less often during peak hours. Precoolers do this by setting their thermostat a few degrees lower than normal during off-peak hours and then setting it a few degrees higher than normal during peak hours (3 p.m. to 8 p.m. weekdays).

“I was very skeptical about precooling,” said Joey Soles, an APS customer who owns a house in Glendale. “I said to myself ‘I’m not turning my AC up at any time during the summer.’ But I tried it and I’m very happy with the results.”

programming a precooling cycle into a smart thermostat
Savings can vary because every house is unique. Some houses are large. Some are small. Some are well insulated. Some are not well insulated. Some absorb more sunlight in the morning. Some absorb more sunlight in the afternoon. We encourage customers to experiment with precooling to learn what works best for their house.

“I’ve saved a ton of money by precooling,” Soles said. “I was getting electric bills ranging from $700 to $800 per month in the summer. So, I replaced my home’s insulation and tried precooling last summer, and I’ve already saved enough money on my bills to counter the cost of replacing my insulation.”

Precooling is catching on in the desert regions of Arizona. To reap the benefits, though, it’s important to understand the timing, service plan and other factors involved.

“The most important aspect when you precool is that whether you start precooling at 11 a.m., noon, or 2 p.m., it has to end at 3 p.m. or else you’re doing yourself a disservice,” said APS’s Jason Delaney, a supervisor of customer technology strategy & development.

So, precisely how long does it take to precool a house? Again, it depends on the house.

“At the very least, you should precool from 2 p.m. until 3 p.m.,” Delaney said. “And you don’t want to just turn your AC off from 3 p.m. until 8 p.m. and then try to make up for what you did later. You want to raise your thermostat a couple of degrees and then let it kick on as it needs to because if you just turn it off during the peak hours, it might take a long time for your house to cool back down.”

Another option is to sign up for our Cool Rewards smart thermostat program, which uses precooling to improve grid reliability on really hot days and rewards customers who participate.

There are many misconceptions about precooling. One is that it costs more money to precool a house.

“It sounds counterintuitive to run your AC more in order to save money, but the Saver Choice plans make this possible,” said Bruce Brazis, an account executive on APS’s Customer to Grid Solutions team. “Running your AC more to precool during off-peak time and less during on-peak time will net you out with bill savings.”

Count Michelle Benbo among the APS customers who are precooling enthusiasts. She said she enjoys not hearing her 17-year-old AC kick on repeatedly during the hottest time of the day.

“Precooling is a win,” said Benbo, who lives in Litchfield Park. “I’m seeing significant savings on my bill because I’m running my AC during the least expensive part of my plan. An added benefit is that I’ve found precooling saves on the maintenance of the AC unit.”

If you can’t handle chilly early-afternoon temperatures followed by warmer late-afternoon temperatures, precooling may not be for you. But we suggest you try it for a few days and adjust based on what works best for you and your house.

Dan Ishac, an APS customer who owns a house in Scottsdale, initially set a precooling range of about 10 degrees. He eventually settled on a five-degree range.

“You’ve got to balance saving money with personal comfort,” Ishac said. “Overall, the concept of precooling is science and there’s no doubt it reduces my electric bill in the summer. So, once you find a comfortable temperature range, there’s really no reason not to precool.”

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