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If you're like many homeowners, there's probably at least one room in your home that doesn't get quite as warm as you'd like during the winter. If so, when you spend time in that room, you've probably weighed the options of donning a sweater, cranking up the thermostat, or buying a space heater just for that room. But are space heaters truly the best way to remedy the problem of a chilly room (or rooms)? And if so, are there energy-efficient space heaters widely available on the consumer market? Perhaps most importantly, are space heaters even safe to operate in your home?

How Do Space Heaters Work?

If you don’t know how space heaters operate, you're not alone. Many homeowners are content with the fact that when they turn a space heater on, the room gets warmer. But to truly understand the benefits and potential drawbacks of space heater use, it's best to have a basic, nuts-and-bolts understanding of what's happening inside a functioning space heater.

First, let's acknowledge that space heaters can run on kerosene, electricity, propane, or natural gas — but for in-home use, we'll stick to electric space heaters. That's because heaters that run on other fuel sources are typically reserved for workshops, industrial areas, or outdoor use and can be unsafe — or even deadly — to operate indoors!

In simplest terms, there are two common types of electric space heaters: radiant heaters and convection heaters. Both types accomplish the same thing, though in different ways and to differing degrees of energy efficiency.

Convection heaters use a fan to force air over a heating element and into a room. This heats the ambient air around the heater, causing that hot air to rise, which sends colder air down to the floor. This process is known as — you guessed it — "convection." In fact, you'll often see space heaters labeled by their manufacturers as "convection heaters."

Radiant heaters, on the other hand, use a completely different process for producing heat. Most contain heating oil, which is electrically heated from within, thus warming the surface of the heater itself. This, in turn, warms the air immediately around it. These typically look much like traditional radiators seen in older homes, with the exception that they're generally portable and plug into a standard power socket as opposed to being built into the home itself.

Benefits and Drawbacks

Both radiant and convection space heaters offer the same benefits. Namely, they provide a quick source of heat to a small enclosed space and have the ability to be moved between rooms as needed and stored safely (unplugged, of course) when not in use.

The drawbacks of space heaters are somewhat more alarming and may outweigh their benefits. First, space heaters are a woefully expensive way to heat a room or home. Let's look at the math:

  • Most electric space heaters in the U.S. run on 1,500 watts of electricity.

  • In the U.S., the average residential electricity rate is 15.64 cents per kilowatt hour (kwh).

  • This means running a 1,500-watt space heater for an hour will cost the average homeowner about 23.46 cents per hour — or about $5.64 a day if the heater remains on all day.

  • Running that heater all day for a 30-day month means the homeowner would incur an additional electricity cost of $169 for that month alone.

Not only are they expensive to run, but both convection and radiant space heaters are inefficient ways to heat a room. Radiant heaters are good at heating you if you're near one, but since they only heat the air immediately around them, once you're more than a few feet from a radiant heater, you won't feel the warmth at all. Convection space heaters can be more efficient if left on for longer, but they also only heat the air in the room, so if a room has a drafty window or the door is poorly insulated, all that warm air will eventually escape.

Lastly, and perhaps most importantly, space heaters can be dangerous. According to the National Fire Protection Association (NFPA), space heaters cause 40% of heating-related fires and are the leading cause of deaths (81 percent) and injuries (80 percent) resulting from heating-related fires.

Do Energy-Efficient Electric Space Heaters Exist?

The answer to this one is pretty simple: No, electric space heaters are, by their very nature, not energy efficient.

Why?

Largely because any measure of their energy efficiency would depend on how energy efficient the space they're operating in is. This is one of the reasons many heaters' claims of being "energy efficient" can be confusing. In a well-intentioned experiment on energy efficiency conducted by BobVilla.com, the team used a reliable and sensible rubric to test each heater's initial efficiency — but they didn't account for the full picture. That's because the team only tested how long a given 1,500-watt heater would take to increase the temperature in a 150-square-foot room by five degrees.

That's a good start, but they didn't account for how much time and energy — and therefore money — would be required to keep that room consistently warmer. If a heater, say, only has to run for 15 minutes to make a room noticeably warmer, but it then has to run 15 minutes every hour to maintain that same temperature, is it truly energy efficient? No, because the room isn't energy efficient.

With that said, there are features some space heaters include that can make them less inefficient, such as thermostats, timers, and even Wi-Fi connections to smart home systems. These can mitigate the energy lost by avoiding ongoing space heater use, but they don't make space heaters energy efficient — just less inefficient.

Related Post: How to Improve Home Health and Lower Energy Bills with Smart Home Technology

Are There Sustainable, Energy-Efficient Alternatives to Space Heaters?

Space heaters can be great in a pinch. After all, no one wants to spend time in a room that's just too cold for comfort. But they should be used, ideally, as a temporary measure until the underlying problem(s) is/are addressed.

"While some space heaters can be more efficient and effective than others, I wouldn't rely on any space heater to heat a home or even a room over the long term," says John Costello, pipeline fulfillment manager at Pearl Certification. "As a building analyst, I always look for why a homeowner would need one in the first place. When a room isn't warm enough or even as warm as the rest of the house, that indicates other problems with the home's envelope, heating system, and/or the distribution system in the home."

Costello added that poor insulation or poor circulation via the home's heat distribution system (or both) should be addressed as soon as possible.

"Ignoring the problem with the envelope or distribution system will continue to cost a lot of money over time," he noted. "Adding the cost of a space heater won’t help with that loss, even if it’s an energy-efficient model."

Additional alternatives to space heaters, Costello suggested, include installing energy-efficient windows and doors, investing in energy-efficient insulation, and updating and improving your home's air sealing.

Related Post: The Ins and Outs of Insulation

Takeaways

When a room's just too cold, a space heater can be a solid temporary measure — but just that: temporary. Using a space heater long-term is an inefficient, expensive, and even dangerous proposition. The smarter choice is to diagnose why your space doesn't get or stay as warm as you'd like and then take proactive steps to address those issues. Consider getting a home energy audit, which will illuminate precisely what you need to do to achieve a toastier home.

Related Post: What's a Home Energy Audit and When Do I Need One?

To learn more about how to keep your home warm — and efficient — during the cold winter months, check out our Winter Home Energy and Resilience Guide and login to the Green Door app to get a customized Home Investment Plan. You can also find rebates and tax credits based on your location, connect with a local, vetted contractor for installations, and even request a Pearl Certification to capture the real value of your new asset and your home.

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