Central AC System GuideThe thermostat is the cheapest efficiency upgrade in the house. Where a homeowner sets it, and how far it drifts while nobody is home, drives a large share of the summer cooling bill. Small, verified adjustments to setpoint and schedule save real money without new equipment.
Raise the setpoint a few degrees
Every degree cooler costs energy. The Department of Energy reports that running the air conditioning at 78 degrees Fahrenheit instead of 72 degrees can save between 6 and 18 percent on the cooling bill.
The reason is simple. A higher indoor setpoint shrinks the temperature gap the system fights against, so the compressor runs less often and for shorter cycles.
Let a ceiling fan do part of the work
Moving air feels cooler than still air. The Department of Energy reports that using a ceiling fan lets a homeowner raise the thermostat setting about 4 degrees Fahrenheit with no reduction in comfort.
Fans cool people, not rooms, so the habit only helps while someone is present. Turning the fan off when leaving the room keeps the savings honest.
Program the schedule
There is no reason to cool an empty house hard. A programmable thermostat raises the setpoint while the home is empty and brings it back down before anyone returns, capturing savings automatically.
The payoff is measurable. The Department of Energy reports that programmable thermostats can save up to 150 dollars a year in energy costs when used properly.
Confirm the thermostat itself is right
A schedule only helps if the settings match the household. ENERGY STAR advises checking thermostat settings to ensure the cooling system keeps the home comfortable when people are present, then relaxes when they are not.
Matching the schedule to real habits avoids the common trap of a thermostat programmed for a routine no one keeps, which quietly erases the savings a good setpoint was meant to deliver.