A woman in a warm sweater at home she has used preheating to keep her home warm.
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Preheat and save

What Is Home Preheating and Why Would I Do It?

Steve Hansen
/
November 21, 2023

Unless you live in a Passive house, home heating can be a costly endeavor. In fact, heating uses nearly 30% of the energy your home consumes, according to the U.S. Department of Energy. Your smart thermostat can help, though. These remarkable devices are designed to learn your family’s ways and help you maximize energy efficiency, along with your comfort. Who cares for being cold, after all? One different way your smart thermostat can help is by home preheating.

Similar to precooling, if you are heating your home with a heat pump, mini split, or electric resistance heating, preheating works with time of use (TOU) electricity pricing to predictably raise your home to a comfortable temperature at off-peak rates. That may mean that when your home is empty on a typical day when everyone is out at work, school, and handling tasks, the smart thermostat takes the temperature down so as not to heat an empty house. Sure, that’s standard operating procedure. But there’s more to it than that.

The Smart Thermostat Is the Boss

Where a smart thermostat jumps in with preheating is by using the last couple of hours of off-peak rates to bring the temperature to your preferred temperature or a bit higher so that the house is warm when you arrive home. Then it stops the heater(s) or furnace, and you get to take a break from peak rates.

A couple of hours later, after peak rates have passed, you can have another round of heating if necessary before the smart thermostat manages the home temperature for the sleeping hours. In the morning, it can warm the house on the schedule it’s learned for you, or according to what you’ve programmed.

If your schedule changes at any time, you just use the app and tell the smart thermostat what you want it to do. Need to go home early and want the house to be warm when you get there? Easy—fire up the app and start the heat instantly. Plus, it’s a smart thermostat, so it learns your daily schedule automatically, and on the weekends, it knows the starting time is an hour later, or whatever it is for your family.

Preheating Is A Greener Strategy

When you use more off-peak energy, you’re giving our strained energy grid a break—not just your own budget. We’ve seen both summer and winter outages in recent years, and both have been catastrophic. And, if you use natural gas or heating oil to heat your home, letting the temperature drift lower when you aren't home or don't mind being a little cooler still saves both energy and money.

Home Improvement Strategies Are Smart Too

Preheating will definitely work best if your home is fairly energy efficient already. But even if you don’t give preheating (or precooling) a try, an energy-efficient home pays off year-round. Your best strategies involve air sealing to make your home more airtight, along with increasing the amount of insulation where your home needs it. Air sealing is pretty easy and we’ll get into it here. Insulation tends to be more involved, but here’s more information from the U.S. Department of Energy.

Air Sealing

Air sealing involves using caulk, spray foam, and some weatherstripping to block the movement of air through gaps and cracks. Most homes have plenty of those, by the way! This is generally quite simple and easy work that pays off instantly. You just need to know where the air leaks are.

A great way to start with air sealing is to get a home energy assessment from a professional assessor. Thanks to the Inflation Reduction Act, you can take advantage of a $150 tax credit on this type of assessment. Your assessor will perform a few tests like a blower-door test to pinpoint the air leaks, and thermal-imaging testing to highlight the warmer and cooler areas in wall and roof planes. When testing is complete, you’ll get a customized report that shows you exactly where you can get to work with both air sealing and insulation improvements. The most common areas for air leakage include:

  • Electrical outlets and switches in exterior walls
  • Loose-fitting doors and windows
  • Gaps around door and window frames
  • Gaps where electrical service enters the house
  • Gaps where plumbing lines enter the house
  • Kitchen and bath fans
  • Plumbing, dryer, and furnace vents.

Those items could be a lot to tackle, but you could start with outlets and switches, drafty doors, and drafty windows. Check out this article for just what to do. Now let’s look at a couple of high-tech additions that are ready to shine in the transition to cleaner energy and help you use less overall.

Almost Everyone Should Have A Heat Pump

Heat pumps are not a new invention, but the technology they use has improved drastically in just the last few years. A hear pump is much like an air conditioner that can run in either direction; it doesn't create any heat, it just moves heat. So, in the summer it can move heat our of your home, and in the winter, it can move heat into your home.

Heat pumps come in air-source versions that just transfer heat from the air inside and outside your home; ground-source versions that use coiled plastic tubing with fluid inside that’s buried a few feet into the ground to transfer the earth’s heat into your home in the winter or to absorb heat from your home in the summer; and water-source versions that use coiled tubing in a body of water, which work like a ground-source system.

Most heat pumps that will be installed in the coming decades will be air source units. They’re the simplest, and they’ll replace the standard boxy metal air conditioning units we see outside most homes. They’re highly efficient units and qualify for a nice tax credit under the Inflation Reduction Act!

And they will save you a lot of money on electricity, too! That’s especially true if you now have electric resistance heating like baseboards in your home. According to the U.S. Department of Energy:

“Today's heat pump can reduce your electricity use for heating by approximately 50% compared to electric resistance heating such as furnaces and baseboard heaters. High-efficiency heat pumps also dehumidify better than standard central air conditioners, resulting in less energy usage and more cooling comfort in summer months.”

Here’s more about heat pumps.

Battery Storage

Since tax credits keep coming up, I’ll mention that the Inflation Reduction Act also created tax credits for battery storage systems, solar systems, wind turbines, heat pump water heaters, and many other energy-efficient products.

If you had a battery storage system, you could preheat your home using grid power, then your smart thermostat and your battery storage system would take your home off grid during peak hours and you use just your own stored power. Later, your system automatically recharges itself when electricity rates are lowest and you’re ready for the next day. Plus, you’re ready for power outages any time of year. This strategy works best, obviously, if you have a very efficient heating system like a heat pump.

Preheating Should Save You Money

With a smart thermostat running the show, you should see some savings with or without preheating. (Most have great rebates too; you could pay next to nothing.) Add some air sealing and you might have an investment of just $50–$200 right there, then ongoing savings. Sounds like easy money to me!

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