If you’ve ever stepped into a house that’s perfectly cool on a hot afternoon, chances are someone planned ahead (give 'em a high-five). Pre-cooling during the summer months (and preheating in the winter) isn’t just about comfort—it’s a way to seriously reduce how much energy your home uses, especially during the hours when electricity costs the most.
By shifting your heating and cooling habits to off-peak times, you can lower your monthly bill and use your system more efficiently. It’s not complicated and doesn't require a full energy assessment, but it does take a little planning.
What Pre-Cooling and Preheating Actually Mean
Pre-conditioning is the simple idea of running your air conditioning or heat before demand on the grid goes up and prices follow.
“One of the smartest things a homeowner can do, especially during peak pricing hours, is to pre-condition the home before energy demand spikes," shares Vinnie Campo, Co-Founder & CEO of Haven Energy. "In summer, running your AC to cool the house before 4 p.m. and then raising the thermostat slightly during peak hours can significantly reduce your home’s energy consumption when rates are highest, lowering your electricity costs.”
He adds, “In winter it works the same way in reverse, heating your home earlier in the day and then relying on insulation to maintain comfort means your heater doesn’t have to work as hard when electricity rates are higher.”
This works best if you’re on a time-of-use electricity plan. These plans charge more during peak hours, typically in the late afternoon and evening, and less at night or early in the morning. By shifting your cooling or heating load to off-peak hours, your HVAC system runs when electricity is cheaper.
Programmable Thermostats Make It Easier
Actually, programmable is good, but a smart thermostat is great. We're currently running the Google Nest Learning Thermostat, with sensors that help optimize temperatures throughout the home.
“[They] make this easy,” notes Campo. “They let you program your heating and cooling around your daily schedule, time-of-use pricing, or even your solar panel production curve. With time-of-use energy pricing becoming more common, this kind of programming isn’t just convenient, but it can save homeowners hundreds of dollars per year.”
If your utility company offers rebates or incentives for installing a smart thermostat, it’s worth considering the upgrade. Many of them do, and it can cut the upfront cost.
How Pre-Cooling and Preheating Save Money and Energy
The energy savings come from two things: running your HVAC system when rates are lower and reducing the overall time your system needs to be on during peak hours. Here’s how it helps you save:
- Electricity is cheaper in off-peak hours
- Your AC or heater runs more efficiently when outside temperatures are milder
- Smart thermostats automate the whole process
- You avoid excessive cooling or heating during the most expensive times of the day
- Some utility companies offer discounts or credits for lowering energy usage during peak times
“See below an example of what the savings can actually look like using one of our customer's bills. This customer lives in California and uses SCE (Southern California Edison) as their utility company. They are on a time-of-use plan (TOUD-4).”
It doesn’t take a full heating or central air conditioning system upgrade to get started. Even just adjusting your thermostat settings a few degrees earlier in the day and letting it rest during the peak can make a noticeable difference in your utility bill.
What’s the best temperature for offsetting energy costs?
In summer, try setting your AC a few degrees cooler in the late morning or early afternoon—then raise the thermostat temperature by 4–6 degrees during peak hours (usually 4–9 p.m.). Overnight when outside temperatures drop, heat transfer is minimized.
In winter, heat your home earlier in the day and set the temperature lower when rates go up. You’ll need to test the comfort level for your home (heat loss can vary due to attic insulation), but even small shifts help.
Can I still pre-cool or preheat without a smart thermostat?
You can, but it's really manual. You can still adjust your temperature settings by hand or use a basic programmable one. Just remember to set it earlier in the day and raise or lower the indoor temperature for energy efficiency. You’ll have to stick to a schedule to make it work.
