Figuring out energy consumption, energy star ratings, and cooling equipment specifications can feel like advanced math. But don’t worry, you don’t have to work for the U.S. Department of Energy to solve the energy savings equation. Let’s take a look at the formula below…
For every ton that your unit weighs, it will use 12,000 British Thermal Units (BTUs). In this example, let’s say your central air conditioner weighs 2 tons with a SEER rating of 15. In this case, 2 tons x 12,000 BTUs = 24,000 BTUs. Then, you’ll divide the BTU total by the SEER rating to discover how many watts of electricity your AC system will use per hour.
24,000 BTUs / 15 SEER = 1,600 watts. Since electric companies bill by kilowatts, you’ll need to move the decimal to the left three times, which results in 1.6 kilowatts.
Then, multiply how many hours you run your split system or central air conditioner annually by the kilowatt usage. Let’s say you run your system for 8 hours per day. That’s 2,920 hours per year. So, 1.6 x 2,920 = 4,672 kilowatts per year.
Then, you’ll want to find out how much you pay per kilowatt on your utility bills. In Hawaii, the average is 37 cents/KwH. 37 cents x 4,672 = $1,728.64 per year, or $144.06 annually.