Q. I am trying to figure out the best way to heat a room that I built inside my garage. I have it insulated and dry walled. I would really like to use an electric heater that has a thermostat. That way I could keep the temperature regulated. I just don't know how much more my electric bill will be. Does anybody have estimation? I have a 1500-watt electric heater with a thermostat, I'm just afraid to use it, because of cost. I need to keep the room at least at 50-55 degrees Fahrenheit.
A. The formula to determine the cost of operation of an electrical appliance is:
Wattage times Hours times Rate divided by 1,000 equals Operating Cost.
The Wattage in your case is 1,500.
Hours is the time it takes to maintain the temperature. Let's assume 15 minutes an hour for the whole day is 6 hours. For 120 days, this comes to (120 x 6) 720 hours.
Rate is what the utility charges you on your bill per kilowatt. For this example, I am going to use $0.12 per kilowatt, but you can substitute the actual amount with the rate on your bill.
In this example: 1,500 x 720 x 0.12 = 129,600/1,000 = $129.60 = Estimated Annual Operating Cost.
To get a better estimate, heat or loss calculations are used. What this does is calculate the amount of heat loss based on the materials in the room (example R-19 insulation) and incorporates national weather data to determine the amount of heat required to maintain a desired temperature inside the room. In other words, heat loss or gain calculations determine the amount of heat required per hour to replace the amount of heat loss per hour in this room.
Energy Conservationists, like me, are professionals who actively work in this industry and get paid by what they save. They must prove it definitively. We do not say "If you insulate your house, you will save 30 percent on your energy bill." In your situation, which would be rare for us to do but was done a lot in the past, your energy history would be analyzed to determine the actual cost of the action. Today meters are used. In your case, the meter is plugged into the outlet and the appliance is plugged into the meter. The readings are used to compare with our estimated cost calculations, which are far more complicated than a heat loss or gain calculation, to determine the accuracy of our estimate calculations. This data is not only used to adjust our calculations but also to support proposals concerning energy conservation.
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