Space heaters: How much energy do they use?
When first arriving at the home, I saw the setup. It was typical – a large master bedroom with a ceiling fan and an irregular shape. The room was cold, but I suspected this had little to do with the efficiency of the heater. In fact, the room was cold because of the following:
- Inadequate insulation
- Old, worn windows
- Obstructed heat vent
- Poor heat circulation
None of these, as you can see, is related directly to the space heater? However, while there, the owner did ask me to verify the energy consumption of the unit.
The label read 1500 watts, though as we know, that isn’t necessarily the case. In fact the unit had 3 settings: Low, Mid, and High. Of course, the higher the setting the more energy is used. But how much exactly?
I plugged in my electric meter, configured it quickly and reset the counters/calculations to zero. Then, I turned it on each setting, giving it a few moments to heat up, so to speak.
- Low Setting: 564 watts
- Mid Setting: 807 watts
- High Setting: 1300 watts
Interestingly, the other dial which adjusts the intensity of the heat(?) does nothing to energy consumption right away. In fact, this simply controls the simple, or dumb, thermostat. So the higher you have it set, the longer the unit will stay on, costing you more energy.
So, what’s the best energy setting? Mid is probably the best bet, provided you have circulation of the warmed air.This will give off the most heat for your energy dollar.
Wait! Why not Low? It uses less energy.
True, and efficiency is obviously a concern here. But take a look at the raw numbers. The energy jump from Low to Mid is less than 250 watts (243 watts). The jump from Mid to High is almost 500 watts. With the thermostat at a moderate setting to low setting on the “Mid” selection, the unit might only be on for let’s say 5 our of 8 hours. If this customer is charged $0.12 per kwh for electricity, their additional energy cost is $0.48 per night it is used. Compare this with the $0.34 it would cost to run the unit for the same amount of time (5 hours) on Low, and the $0.78 it would cost to run the unit at High for the same time. Obviously, this isn’t exactly realistic, but we can’t estimate the time the unit would actually be on without doing some more calculations and actually observing the unit.
Obviously, the recommendation is to use the heater on this setting as a short term solution. The windows and insulation need work, along with the ventilation/hvac ducts. The circulation can be remedied partially by using the ceiling fan.