The electric blanket takes round three of #EnergyFaceoff! | Graphic by Stacy Buchanan, National Renewable Energy Laboratory
It can be tempting to try to add heat to the space around us, rather than using smaller solutions to warm ourselves. If you are debating between a space heater and an electric blanket to keep warm in an isolated space, the electric blanket will almost always be the more energy-efficient choice.
The wattage of a space heater will vary with the heater and the size of the room it's meant to heat, but most will use 750-1500 watts (W). Electric blankets, on the other hand, use more like 400 W. If, for example, you used each for 8 hours at a time, 50 days per year, here's how your costs would break down:
Space Heater (low end of energy use):
(750 W x 8 hours) / 1000 = 6 kWh/day (daily consumption)
6 kWh/day x 50 days = 300 kWh (annual energy consumption)
300 kWh x $0.11 = $33 per year
Space heater (high end of energy use):
(1500 W x 8 hours) / 1000 = 12 kWh/day (daily consumption)
12 kWh/day x 50 days = 600 kWh (annual energy consumption)
600 kWh x $0.11 = $66 per year
(400 W x 8) /1000 = 3.2 kWh/day (daily consumption)
3.2 kWh/day x 50 days = 160 kWh (annual energy consumption)
160 kWh x $0.11 = $17.60 per year
Of course, if you can manage without an electrically added source of heat, the most efficient way to warm up is to add extra clothing or blankets—you'll have no additional electricity costs, and you won't have the added safety concerns that that both space heaters and electric blankets can present.
If the room that feels cold is already conditioned, you may want to look into other weatherization measures to keep it warmer. You might first start with a home energy audit to identify where you are losing energy. You might also look for air leaks and ensure the room is well-sealed. You may also want to look into adding more insulation. And if you're still interested in a portable heater, check out our tips on selecting the right heater and using it safely and efficiently, or see the home heating infographic.