Supercooling is having a moment.
So what is supercooling, and how can it help you save on your electric bill this summer?
Supercooling, also known as pre-cooling or subcooling, takes advantage of Time of Use (TOU) rates by shifting your energy usage to off-peak periods when electricity is cheaper.
Here’s how it works:
Overnight supercooling: One way to do it is to run your air conditioner overnight, when rates are cheapest and the temperature outside drops to its lowest level, so your A/C doesn’t have to work as hard or use as much energy to fight the humidity. You’ll just have to make sure you maintain that cooler temperature until 4PM when on-peak TOU starts.
Midday supercooling: The other strategy is to do your supercooling from 12-4PM. These are the last off-peak hours for TOU, so you are getting your home to its coolest level right before the rates jack up for on-peak hours. The disadvantage here is that this is among the hottest parts of the day, so your A/C will be fighting the afternoon sun.
It’s anecdotal, but one person who used this strategy in Phoenix, Ariz., reported that he cut his monthly bill by $81. (He adopted the supercooling strategy after seeing his monthly bill hit $340 in July.)
One study found that California residential air conditioning represents about 15% of the state’s peak energy load, but only 2% of its total annual electrical consumption. The research found that an annual pre-cooling and nighttime ventilation cooling strategy could save 24% for a typical new construction home in Sacramento.
In some cases, supercooling actually used more total electricity. But that increased energy consumption happens during off-peak hours, and saves you from on-peak pricing. So even though it uses more energy, you pay less out of pocket (and the extra energy comes when renewable resources are abundant, so it’s better for the environment too).
We recently did an in-house study of supercooling with five OhmConnect employees in various climates and found that it took on average about a half hour to reduce the home’s temperature by 1°F. From this we deduced that it’s best to start pre-cooling at 2PM to bring the temperature down by 4°F before on-peak TOU rates start at 4PM.
Ready to give supercooling a try?
Here are some tips to attain optimum chill:
Your mileage may vary based on your home. Supercooling works best in well-insulated houses with a heat-reflecting roof. You’re also better off in hot, dry areas -- high humidity can put a real damper on supercooling and make it difficult to achieve results.