It’s true that central units will use a lot more power than, say, a single window unit on each floor of a two-story dwelling. But if you have more than two rooms to cool, then your best bet is to go with a central unit, which also provides long term resale value and humidity control. “Well-designed central systems win out in terms of being able to filter the air for allergens and pollutants, and for controlling humidity.”
If humidity isn’t your problem, but you’d just like to cool your home, you could get away with one window unit on each floor, if your home is well insulated. Keep in mind that window units aren’t necessarily more energy efficient than central air units. A window unit that is too small to cool a room may run continuously, wasting energy. Central air units cool multiple rooms more quickly and filter out airborne particles-but they also use more power than window units. When you’re shopping for a central air conditioning system, make sure the SEER number (Seasonal Energy Efficiency Ratio) is 13 or better.
If you’d rather go with window units, then consider these factors:
- Look for an EER (Energy Efficiency Ratio) of 11 or higher for room air conditioners. Today’s ACs use 30% – 50% less electricity than 10-year old models.
- Make sure your AC is sized properly. It is important to use the right size AC. Select a unit that removes an average of 20 BTUs per square foot of living space or higher.
- Clean your AC filter every month. A dirty filter makes your AC work harder, which uses more electricity. Regardless of the type or age of the unit, be sure to change filters after every 90 days of use.