Why Does Running My AC Cost So Much?

Electric bills in the summer can get very expensive. For the 95% of us in the South Atlantic United States that use air conditioning, the reason is pretty obvious. A/C units take energy to cool your house from the 90 degrees it is outside to something a lot more comfortable inside.

The good news is that air conditioners are becoming much more efficient. In the 1990’s energy use for heating and cooling a home was more than 50% of all a home’s energy consumption. By 2009, it dropped below 50% of household energy use nationwide. The federal government lists more efficient heating and air conditioning equipment, along with better insulation and windows as key factors. Yet, not everyone is seeing smaller bills during the summer.

What is average for Air Conditioning Costs?

In 2011, a New York Times article estimated it costs about 36 cents/hour to run an average central air conditioner. Electricity costs have risen a bit, so in 2018, the cost to run that same central air conditioner (a 3-ton unit) is about 39 cents/hour.  Most A/C units won’t run 24 hours a day, but they might run 60% of the time in hot weather. So factoring that in, that’s just under $5.75/day or $172 dollars per month. If you have a larger A/C unit, your costs will be higher.

This isn’t the total cost of your electricity bill either. It will be higher from running your appliances, charging your phone, and lighting your house. But this gives you a general guideline as to whether your bill is way out of line with what it should be from your A/C unit running.

4 Home Problems That Increase Your AC Cost

If you are paying a lot more than average for air conditioning, it could be a problem with your house, a problem with your A/C unit or both. Here are a few things to consider that could be causing the problem.

Thermal Image of House showing leaks leading to rising ac cost

Your Windows are Leaky

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. In extreme cases, new windows might be worth the investment.

Not Enough Insulation

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.

The Department of Energy estimates that the average Charlotte area homeowner could save 14% on heating and cooling costs each year with proper air sealing and insulation.

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 in the House

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 Causing Your Bill to Rise

two air conditioning units outside a house

Air Filters are Dirty

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. Wondering what air filter to use? Read our guide to replacing your air filter.

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 Air Conditioning Maintenance Issues

Dirty coils and even small problems with your A/C unit can reduce efficiency of your A/C system and lead to higher bills. The best solution is to set up a routine service plan to keep things running smoothly every year.

Wrong Coolant Levels or Coolant Leak

The last person who serviced your A/C 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. Too much coolant can cause similar problems to too little coolant.

Old A/C Unit

The A/C 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.

Your Bill Can Be Impacted by Your Choices

How low do you set the temperature in your home? The most common response in the Carolina’s is 75 degrees. If you like your house cooler, especially during the day, it is going to impact your electric bill. Your A/C unit may be efficient, but your power bill will increase for every degree of cooling. Setting your A/C 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.

Solutions to Lower Your Cooling Bill

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.

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