facebook noscript

How Much Electricity (Kilowatts) Does My AC Really Use?  

Know the Facts About Your System and the Benefits of a Newer One 

Electricity, AC

In today’s world, most people want to save energy, and everybody wants to save money when it comes to their HVAC system. Besides, “how much electricity does my current air conditioner really use?” is probably one of the most frequent questions asked of any heating and air conditioning professional. While it involves some heavy lifting when it comes to math, it’s relatively easy to calculate if you know how.

Before we get to the math, the quick answer is that it starts with knowing the amount of power you use with your HVAC- a calculation explained below. Once you have that number, you multiply it by the time of usage.

We’ll let Air-Tro CEO Bob Helbing explain: 

“It comes down to a formula using the basic measure for seasonal efficiency for air conditioners : the Seasonal Energy Efficiency Ratio. This calculation also uses a numerator measured in BTUs, while the denominator is in watt-hours. It’s a mix of imperial and metric measurements which might seem confusing at first, but bear with me.”


“To calculate cost of energy output, first take your system’s BTU capacity (for a 3-ton unit, that’s 3 x 12,000 BTU/hr. or 36k BTU/hr.) and divide by its SEER  rating (let’s say it’s 12 for an older unit) and you’ll get an electricity consumption of 3,000 watt-hrs. or 3 kilowatt hrs. At Southern California Edison peak rates of 53 cents per watt hour, that means it will cost you $1.59 an hour to run. Keep in mind that as your HVAC system gets older, your SEER rating may have gone down in terms of efficiency. What was SEER-rated 16 ten years ago may be 12 now.

seer savings calculator
Use the energy savings calculator at lennox.com to see how much you could save.

To figure out your annual cost of AC, consider that an average “cooling load” (i.e., the total number of hours you spend running the air conditioning) is probably something like 1,500 hours per year. $1.59 x 1,500 peak-rate hours would be $2,385 dollars per year to keep your house cool. Now, it’s unlikely that all your air conditioning needs will be during peak hours, so call it $2,000.

When considering a new unit, let’s assume you purchase a system in 2022 that’s rated at 24 SEER, not the 12 of your old equipment. Now, you’re halving the cost of your AC operation per year to $1,000.”

In summary, as you might imagine, newer air conditioning systems are far more energy efficient and thus use less power to maintain indoor comfort than the products of years past. In other words, today’s HVAC does more and costs less to run. If your older system is getting more and more expensive in terms of its annual electricity costs to maintain indoor comfort, coupled with the price of any new repairs it may need, you may find that buying a new one is far more economical.

Have questions about your HVAC system and the best ways to save on running and maintaining it? Call the experts at Air-Tro today. We’ve been the heating and air conditioning pros for the San Gabriel Valley since 1969! Call us today at (626)357-3535.