Here are some tips for getting the most out of your air conditioning in terms of both comfort and energy savings.
Block the sunlight: Close window coverings on the sunny sides of the house during the day, Sachs said. Longer term, you can consider measures such as adding awnings or planting trees to provide shade.
Close the windows: It’s surprising how often people seek relief by opening windows while the air conditioning is running, said Mike Foraker, president of Jennings Heating and Cooling in Akron, Ohio. But all that does is let in hot, moist air.
Air conditioning works in part by removing moisture from the air. If you keep adding humid air to the house, the air conditioner struggles to dry it. Then the indoor air never reaches a comfortable temperature and humidity.
Leave the unit on: People sometimes turn the central air conditioning on only at night to save money. That’s fine when the weather isn’t too hot, but it’s a bad idea when the temperature reaches 90 or so, Foraker said.
Turning off the air conditioning in extreme heat lets warmth and moisture build up in the house, he explained. The unit can’t eliminate them quickly enough to make the house comfortable at night, and it uses a lot of electricity trying.
Clear the condensing unit: The outdoor condensing unit needs outside air to blow across the heated refrigerant, which is how hot air gets expelled from the house.
Make sure the condenser has enough space around it to permit a good air flow. Trim any plants that are growing close to the unit, and make sure no mulch, grass or debris blocks the bottom openings.
Karl Bella, an energy auditor who runs Energy Pros of Ohio in Richfield, recommends a clearance of at least 8 inches all around. Sachs prefers 3 to 4 feet, if possible.
Check the air filter: In almost every forced-air system, the furnace filter is also the air-conditioning filter. If it gets clogged, air flow is reduced.
Change or clean it as often as the manufacturer recommends, usually every one to three months.
Set the fan on automatic: Conventional wisdom used to dictate running the fan on an air conditioning system constantly to keep air moving throughout the house. Newer research suggests otherwise, Bella said.
Leaving the fan running increases what’s called the stack effect, the tendency of a house to pull in outside air to replace air that rises and escapes through openings high in the building. The more hot outside air comes in, the harder the air conditioner has to work, he said.
In addition, Sachs noted that when the fan runs nonstop, the moving air picks up moisture from the saturated coils when the compressor isn’t running. That defeats the unit’s purpose of drying the air.
Mind the registers: Central air conditioning works best if air can flow through the house freely. If necessary, move furniture so it’s not blocking supply registers or cold-air returns, Bella said.
Don’t be tempted by magnetic covers designed to block air returns. It may seem logical that they’ll keep the cooled air in a room, but instead they just keep the air from returning to the central unit.
Be careful about trying to save money by closing the supply registers in unoccupied rooms. Overdoing it unbalances the air flow throughout the house and results in cool and hot spots, the American Council for an Energy-Efficient Economy says.
Leave the oven off: Even when it’s closed, an oven adds as much heat to the air as an air conditioner can take out in the same amount of time, Foraker said. Grill outdoors, order takeout, make a salad for dinner — just don’t cook indoors on the hottest days.
Turn out the lights: Incandescent light bulbs turn only 10 percent of the electricity they use into light, Foraker noted. The rest becomes heat. Turn off unneeded lights or switch to cooler compact fluorescent bulbs.
Use ceiling fans: They move air over the skin, evaporating perspiration and making you feel cooler. Running one even when the air conditioning is on will increase your comfort, Foraker said.
The fans also help move air around the room, but only to a degree. It’s not enough of a benefit to justify leaving a ceiling fan on in an unoccupied room, the Alliance to Save Energy says.
Minimize humidity: Don’t add more moisture to the air than necessary. Run exhaust fans when you shower, and run hot-water appliances such as dishwashers and clothes washers in the evening, the American Council for an Energy-Efficient Economy recommends.