Air conditioning is among the biggest users of electricity in homes that have it. Over 55 percent of Oahu homes now have air conditioning, from a single window unit to central air, up from 22 percent just 25 years ago.

Consider using a fan instead of air conditioning to reduce your use of electricity. But, if you must use the air conditioner, here’s how to use it wisely to stay comfortable, conserve energy, reduce dependence on foreign oil, save money and protect the environment during Hawaii’s warmest months. For a printer-friendly version of Hawaiian Electric’s Cool Tips brochure, please click here.

Turn down your A/C Run your A/C on as low (that is—as warm) a setting as possible to still be comfortable, and turn off the A/C in empty or unused rooms.

Clean or replace filters on your air conditioner Clean or change your filter per the manufacturer’s specifications – generally once a month for cleaning. A clean, well-maintained cooling system is more efficient and lasts longer because it does not work as hard.

Change your hot lights Replace old-fashioned incandescent light bulbs with cool and efficient compact fluorescent light bulbs (CFLs). CFLs use about 75% less energy, last longer and are cooler so they won’t heat up your home.

Chill on time A programmable thermostat can help keep your home comfortable efficiently. Program your cooling system to turn off while the house is empty and then automatically turn on before everyone gets home. Ask your A/C dealer or local hardware store for a thermostat that will work with your unit.

Get a checkup Schedule a cooling system maintenance check with a licensed contractor to ensure your central or split system is working safely and efficiently.

Cut the glare Install awnings, blinds or film tinting on south and west windows to block out the warm afternoon sun and keeping your cooling system from working overtime during the hottest hours of the day.

Replacing your cool If your cooling system needs replacing, consider an energy-efficient ENERGY STAR® model. Check the Energy Guide label for operating efficiency, measured by Energy Efficiency Ratio (EER) or Seasonal Energy Efficiency Ratio (SEER). The higher the EER or SEER, the more energy efficient the unit will be. Units with higher EER or SEER may cost more, but the efficiency will repay that over and over again during its lifespan.

Custom fit Purchase the right size cooling system and have it installed properly, so your investment will deliver on its full energy-performance promise. An undersized unit will not handle the heat, causing it to overwork and not perform optimally. An oversized unit cools quickly but can create a “cold and clammy” feel due to high humidity.

Check HECO’s guide to selecting a properly sized window air conditioner. If you are purchasing a central or split system, Hawaiian Electric recommends getting two to three estimates from different licensed air conditioning contractors.

On the shady side Cooling systems should be installed in a shaded location. Consider planting leafy trees and shrubs strategically to provide shade from the sun while beautifying your home. Be careful to keep plants from blocking air flow! Shade provided by trees can also reduce your air conditioning bill by 10 to 15%. A single tree will absorb one ton of carbon dioxide over its lifetime. The Arbor Day Foundation has information on planting and provides trees you can plant with membership.

Seal the deal Leaks in windows, doors and walls let cool air out and hot air in, so check your home for drafts and seal leaks that can make your cooling system work overtime.

Insulate and weatherize your home. Properly insulating your walls and ceilings can save on your home cooling bill. The Consumer Federation of America has more information on how to better insulate your home.

Install a solar attic fan. Use a solar powered attic fan to draw out hot air and reduce attic temperatures by as much as 40% with clean, free power from the sun. Consult a professional for installation or DIYers can read here for step-by-step instructions.