CLEVELAND, Ohio — With cold temperatures hitting the U.S., I’ve seen many articles about buying an electric space heater. They all repeat the same claim: If you turn down your thermostat and use space heaters in targeted areas of your home, you’ll save money.
I’m using the word “claim” because that theory smells fishy at best. At worst, I think it’s total nonsense.
I’m not against space heaters. I own one myself. And yes, lowering your thermostat will reduce your heating bills. That is, of course, if everyone else in your house isn’t raising the temperature when you’re not looking.
But if you’re turning down the thermostat and then turning on a space heater for just a bedroom or an office, I’m willing to bet that you’re losing money instead of saving it.
How do I know? Because I was silly enough to (A) buy plugs that can measure how much electricity an outlet uses and (B) subject my home to experiments.
Before I complain more, I should at least explain the theory behind why a space heater might save you money on your heating bills.
Your furnace is designed to heat your whole home, which is inefficient. Most of the time we’re only using one or two rooms. Heating unused rooms is wasting money.
When no one is home the ideal solution is a programmable thermostat. It can automatically lower the temperature while you’re gone or while you’re sleeping.
The space-heater theory says you can turn down the thermostat while your home, too.
Instead of paying to heat the whole house, you can just use a space heater to warm up your bedroom or your office. The house might be cold but the room you’re in is toasty.
This only works if your space heater is cheap enough to use. If it uses enough electricity, it will cancel out the savings on your heating bills.
So, how much does a space heater cost to use?
There’s a whole range of expensive and cheap space heaters that you can buy. We don’t need to test all of them, because almost all electric space heaters are rated for 1,500 watts or less.
That’s generally the most power that can safely come through an average outlet. At a maximum, a space heater should use 1.5 kilowatt hours of electricity per hour.
They’ll likely use less, because many heaters have built-in thermostats and turn off once the room is heated. This is where an experiment is needed.
We have two experiment rooms. A home office that needs to be slightly warmer and a basement bathroom that’s 10 degrees cooler than the rest of the home.
The bathroom is a stand-in for a bedroom, assuming you turn the thermostat down by 7-10 degrees, which is what the U.S. Department of Energy recommends. If I turned my house’s thermostat to 61 degrees, I’d be newly single by the morning. So, bathroom it is.
To calculate costs, we’ll use the average price of electricity in Ohio, which according to the U.S. Energy Information Administration is 16 cents per kilowatt hour.
For the office experiment we dropped the thermostat by a few degrees. Then we used the space heater to warm the office from 69 degrees to 72 degrees.
The space heater turned on and off periodically and used just under 3 kilowatt hours of electricity over an 8-hour period. At 16 cents per kilowatt hour, that’s 48 cents.
For the bathroom it was the same experiment but from 61 degrees to 71 degrees. The heater ran frequently and used just under 8 kilowatt hours, or $1.28 over 8 hours.
It sounds cheap. But at that price the space heater is likely more expensive than just using your furnace.
I’ve searched around the internet, asked government agencies and local utility experts. When it comes to turning down a thermostat there’s no great estimate on how much money it will save, on average.
Why? Well, every home is built differently, and every day has a different weather pattern. With variables like insulation, leaky windows and sunshine, it’s difficult to estimate heating costs.
Many articles that claim you’ll save money offer no estimates at all. There is one number from the U.S. Department of Energy we can rely on.
If you lower your thermostat (or raise it during air conditioning season) by 7 to 10 degrees from its normal setting, you will save “as much as 10% on heating and cooling.” We also know, because of the U.S. Energy Information Administration, what it roughly costs to heat homes across the country.
In the Midwest, households that heat with natural gas will pay $581 on average from November through March. Electrically heated households will pay $1,213. To be clear these estimates are for total bills, so the cost of running TVs and dryers is in the mix.
Let’s assume you drop the thermostat by 10 degrees. Natural gas households should save $58 and electric households $121 over the entire five winter months.
Not enough to make the space heater worth it.
Say you want to warm up your bedroom. Making a room 10 degrees warmer with a space heater for eight hours costs $1.28. That’s $38.40 every month if used every day, or $192 all winter.
If you’re just keeping your office a few degrees warmer, it’s closer to $15 a month.
So, a space heater doesn’t save you money
I’m guessing you feel vindicated or angry. (If you were indifferent, you wouldn’t read this far.) While this isn’t an exact science experiment, here are some takeaways.
Every money-saving tip comes with a “it depends” asterisk. But if electric space heaters were a viable cost cutter, the math wouldn’t be so cut-and-dry against them.
Personally, I’d do whatever you find comfortable. I’m not sleeping in the cold (or heat) to save $100-$200 a year. And I’m not employing a space heater strategy for potentially thin margins.
The easiest thing to do is to turn down the thermostat when you’re not home, like while everyone is at work or school. Others who don’t mind the cold can also do this while they’re sleeping — and they’ll save money if no space heater is used.
That doesn’t mean you shouldn’t ever use a space heater. Say you live in a two-story home and there’s a bedroom that’s farthest from the furnace. It might be better to use a space heater than to crank up the heat for the whole house.
Now there are some pro-space heater articles that do math and disagree with me. Say for instance that you turn the thermostat down at night. If the furnace doesn’t turn on at all — you may be able to calculate more savings.
I don’t believe eight hours of a lower thermostat setting gives you a 33% cut in your bill, and the Department of Energy only claims a 10% reduction.
If you’re reading an article that’s trying to sell you a space heater, maybe don’t trust them when they say a space heater will save you money.
Now if I was trying to sell you something, I’d advise you to buy an oversized blanket hoodie (it looks like a Snuggie but in the form of a hooded sweatshirt.) This has been my strategy for working in a cold basement. You’ll look silly, but I bet you’d be warmer.
Read past columns at cleveland.com/topic/saving-you-money/.