Cheapest Hours guide
Time-of-Use Rates and Heat Pumps
A heat pump can shift some electricity use by pre-heating or pre-cooling before peak hours, but comfort, weather, insulation, and equipment size limit the practical shift.
The building is the battery
Walls, floors, furniture, and indoor air store heat for a short time. A thermostat can gently move the temperature before a peak period, then reduce compressor use while electricity is expensive.
The best strategy is usually a small adjustment, not a dramatic temperature swing. Homes with good insulation and air sealing hold the benefit longer.
Winter and summer are different
In winter, pre-heating may work before an evening peak, but very cold mornings can create a different system peak. Avoid settings that trigger inefficient electric resistance backup heat.
In summer, pre-cooling before a late-afternoon peak can reduce compressor operation during the hottest hours. Humidity control and indoor comfort remain important.
Estimate with caution
Cheapest Hours assumes 400 kilowatt-hours per month during four expensive months and treats 30 percent as movable. This is intentionally conservative and is the least certain household estimate on the site.
A thermostat history or utility interval-data portal provides a better estimate. Compare several similar-weather days before and after changing the schedule.
When not to shift
Do not compromise health, freeze protection, humidity control, or required ventilation. If occupants are sensitive to temperature changes, prioritize comfort and use smaller adjustments.
Rate rules and prices change. Confirm your plan with the utility before making a financial decision.
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