Heat wave on a time-of-use plan? How to cool your home for less

During a heat wave, the hottest part of the day lines up badly with your bill. On a time-of-use plan, where the price of electricity depends on the hour, the most expensive window is usually 4 to 9 p.m., just when the house has soaked up a full afternoon of sun and the air conditioner works hardest.

Why timing matters. Every kilowatt-hour (kWh) your air conditioner uses during the peak is billed at the peak price. The same kWh used before 4 p.m. is billed at a lower off-peak price. You cannot avoid cooling during a heat wave, but you can move some of it into cheaper hours. Your plan's exact prices are on your bill and your utility's rate page.

A note for October. PG&E's summer pricing season runs June 1 to September 30, so an early October heat wave falls under winter prices. Its plan with peak pricing from 4 to 9 p.m. every day keeps that evening window, at winter prices.

Step 1: Pre-cool before 4 p.m. Southern California Edison suggests running the air conditioner in the morning and early afternoon, before the peak, to cool the house while electricity costs less. Lower the thermostat a few degrees ahead of time, then let the house coast through the evening.

Step 2: Set a steady target. SCE recommends 78 degrees when you are home and 85 degrees, or off, when you are away, and says that can reduce cooling costs by up to 10 percent.

Step 3: Add a fan. The Department of Energy says a ceiling fan lets you raise the thermostat about 4 degrees with no reduction in comfort. Set ceiling fans to spin counterclockwise in summer. Fans make people feel cooler without lowering the room temperature, so turn them off when you leave the room.

Step 4: Block the sun. Close blinds and curtains during the hottest part of the day so sunlight does not heat the house.

Step 5: Move other big loads. Run the dishwasher, washing machine and dryer, and charge an EV, before 4 p.m. or after 9 p.m.

Step 6: Keep the system ready. SCE says replacing air filters every one to three months improves efficiency, and yearly maintenance catches problems early.

Comfort and safety come first. If anyone in your home is vulnerable to heat, keep them cool even if it costs more.

Today's next step: set your thermostat schedule to do its extra cooling earlier in the day and hold at 78 from 4 p.m. on.