Why Does My AC Cost So Much?

Electric bills in the summer can get very expensive. But what can you do when it is 90 degrees outside and you’re trying to keep your house comfortable. There are a number of reasons your ac cost is making your power bill get out of control this summer. You may have a problem with your current air conditioning unit or it could be something else.

Problems with Your Home Causing a Rise in Your AC Cost

Thermal Image of House showing leaks leading to rising ac cost

Your Windows

Your windows are the top energy leak in a typical home. When you are a trying to cool your house, they are letting in heat. One option to reduce solar heat gain through windows is to have your home’s windows professionally tinted. You could also install solar shades or use thermal curtains.

You should also check windows for leaks. Caulk and add weather stripping to drafty windows to help block as much hot air as possible.


Have you checked the insulation in your attic? We’ve found missing insulation, insulation that is clogging the air venting in the attic, and of course, too little insulation. The cost of adding a lot of insulation probably isn’t going to reduce your cooling bills enough to make it worthwhile, but you should make sure your attic is at least completely covered in insulation and that it is at recommended levels. In the Charlotte area, that means reaching an insulation level of R-30 to R-60.

Too Much Moisture

The old saying goes, “It’s not the heat, it’s the humidity.” And that is true for your comfort inside as well. Your Air Conditioning Unit acts as a dehumidifier, but if you have a lot of moisture in your home, it is either going to have to work harder or it won’t ever effectively remove enough humidity to improve comfort. Look for water leaks (can be as simple as faucets dripping) and use exhaust fans in the bathroom when showering to keep moisture levels down.

Heat Generation

Heat generated by appliances/lights in your home. Some things you don’t want to or can’t turn off. Using fluorescent or LED lighting will help reduce heat gain in the house, as will turning off heat generating appliances and electronics.

Problems with Your HVAC System

two air conditioning units outside a house

Air Filters

Clogged Air Filters are pretty common. When Air Filters get clogged they keep air from flowing properly and make the blower work harder. This can increase the energy consumption and make your cooling bill higher.

Leaky or Poorly Designed Duct Work

If your ducts are leaking a lot of cool air out into the attic, then it like leaving a window open with the AC on. We’ve found ducts that are disconnected and especially in older homes, the joints where the ducts are connected may leak quite a bit. Older flexible ducts develop holes because they simply were not designed to last forever. Learn More about Ductwork in some of our other articles.

Other Maintenance Issues

Dirty coils and other small problems with your AC unit can reduce efficiency of your AC system and lead to higher bills.

Wrong Coolant Levels or Coolant Leak

The last person who serviced your AC may have set the coolant level wrong, or you might have a leak in your system that has not yet drained all the coolant, but is causing the unit to run less efficiently.

Old AC Unit

The AC Unit is getting old and just isn’t as efficient as it should be. If your unit is more than 10 years old, replacement could result in an Air Conditioner that is 20-40% more efficient than your current one. That translates right into savings on your cooling bill.

Choices You Make

How low do you set the temperature in your home? Your AC unit may be efficient, but your power bill will increase for every degree of cooling. Setting your AC to 70 degrees could increase your power bill by 15% or more over having it set at 75.

Do you set the thermostat up when nobody is home? A smart thermostat that senses when people are home or a programmable thermostat allows you to adjust the temperature, so you are not keeping the house as cool when you are not there and can still have it cool down when you return home.


We can help you with your overall comfort and improving the efficiency of your cooling system. If you feel you are paying too much for the cooling that you are getting, let us know. We’re happy to schedule a no obligation consultation to help you determine the right solution for your Charlotte area home. Need Repairs? We can help with that too.