http://www.greenlivingonline.com/HomeGarden/can-portable-space-heaters-be-green/
(Feb 19, 2008)
Space heaters are handy for heating up single rooms while you turn your furnace down. But will their energy consumption leave you cold? Green Living's Mark Mallett delves into the problem. 
When my wife and I made the decision to seal up our forced-air vents, we decided to supplement our heat using portable electric space heaters.
Turn up the heat
Our first concern was finding energy efficient heaters. Here’s the thing: turning electricity into heat is almost 100 percent efficient but one thing separates the proverbial bargain bin discount model from its $100 cousin: controllability.
Electrical math
Electric space heaters measure their power usage in watts, with 1500-2000 watts being the maximum output for most heaters. Your power company, on the other hand, measures your electricity consumption in kilowatt hours (Kwh): one kilowatt is the same as 1000 watts, and 1Kwh basically means you’ve had a 1000-watt appliance running for an hour.
So if you leave your 1500-watt heater running for an hour, you’ve used 1.5 Kwh. Let’s say you are paying 15 cents per Kwh, that’s 22.5 cents an hour, or $5.40 a day. Leave that heater running for a month, you’ll burn through 1116Kwh at a cost of $167.40 -- for a single heater.
Conventional means all or nothing
It’s either on or off with cheaper models -- burn 1500 watts or nothing. It's hard to save energy or keep your costs done since using the heater only a few hours in the morning and evening can cost up to $150 over a six-month period.
This is where the more expensive models quickly earn their keep. For a few extra dollars upfront, you can buy a dual-setting heater, so that you’re only burning 1000 watts on the low setting (still a lot of energy but somewhat of an improvement). A $100 plus heater gives you a wider variety of settings, some even have an actual thermostat. These high end models quickly pay for themselves since they allow you to control how much energy you use.
Blowing energy out the window
The next dilemma is radiant heat vs. fans. Fans are generally available on relatively cheap models and have the advantage of helping to heat a room quickly. The downside is that blown air doesn’t hold heat for very long, so when the heater shuts off, your room also cools quickly.
Radiant heaters, on the other hand, use electricity to heat some kind of thermal mass (often oil), which then radiates the heat into the room. They take longer to warm up, but combined with a thermostat, they’re able to cycle power on an off and still maintain a constant temperature. For my money, radiant heaters are the way to go, both for comfort and energy efficiency.
Hydro plays a part
Whether or not your space heater is green also depends on the source of your electricity. If your hydro is coming from a green source (hydro, wind, solar, tidal or biomass), then your space heater is green. Hydro from a fossil fuel-burning power plant or nuclear power plant means your heater can never really be green. If you don’t have the luxury of buying green hydro, then it may be more energy efficient to buy a vented, gas-burning space heater.
Safety first
Green or not, fire safety is a serious concern with all portable heaters. Make sure you keep them at least one metre from anything combustible (including curtains, bedding, etc.). Never leave them running when you’re either asleep or out of the house and keep small children away from the heat. For more complete safety tips, go to Canadian Standards Association.
Mark Mallet is a LEED Accredited professional consultant who writes about the green construction industry from his warm and cozy home in Nelson BC.
Can portable space heaters be green?
Image: istockphoto.com/Sharon Meredith
When my wife and I made the decision to seal up our forced-air vents, we decided to supplement our heat using portable electric space heaters.
Turn up the heat
Our first concern was finding energy efficient heaters. Here’s the thing: turning electricity into heat is almost 100 percent efficient but one thing separates the proverbial bargain bin discount model from its $100 cousin: controllability.
Electrical math
Electric space heaters measure their power usage in watts, with 1500-2000 watts being the maximum output for most heaters. Your power company, on the other hand, measures your electricity consumption in kilowatt hours (Kwh): one kilowatt is the same as 1000 watts, and 1Kwh basically means you’ve had a 1000-watt appliance running for an hour.
So if you leave your 1500-watt heater running for an hour, you’ve used 1.5 Kwh. Let’s say you are paying 15 cents per Kwh, that’s 22.5 cents an hour, or $5.40 a day. Leave that heater running for a month, you’ll burn through 1116Kwh at a cost of $167.40 -- for a single heater.
Conventional means all or nothing
It’s either on or off with cheaper models -- burn 1500 watts or nothing. It's hard to save energy or keep your costs done since using the heater only a few hours in the morning and evening can cost up to $150 over a six-month period.
This is where the more expensive models quickly earn their keep. For a few extra dollars upfront, you can buy a dual-setting heater, so that you’re only burning 1000 watts on the low setting (still a lot of energy but somewhat of an improvement). A $100 plus heater gives you a wider variety of settings, some even have an actual thermostat. These high end models quickly pay for themselves since they allow you to control how much energy you use.
Blowing energy out the window
The next dilemma is radiant heat vs. fans. Fans are generally available on relatively cheap models and have the advantage of helping to heat a room quickly. The downside is that blown air doesn’t hold heat for very long, so when the heater shuts off, your room also cools quickly.
Radiant heaters, on the other hand, use electricity to heat some kind of thermal mass (often oil), which then radiates the heat into the room. They take longer to warm up, but combined with a thermostat, they’re able to cycle power on an off and still maintain a constant temperature. For my money, radiant heaters are the way to go, both for comfort and energy efficiency.
Hydro plays a part
Whether or not your space heater is green also depends on the source of your electricity. If your hydro is coming from a green source (hydro, wind, solar, tidal or biomass), then your space heater is green. Hydro from a fossil fuel-burning power plant or nuclear power plant means your heater can never really be green. If you don’t have the luxury of buying green hydro, then it may be more energy efficient to buy a vented, gas-burning space heater.
Safety first
Green or not, fire safety is a serious concern with all portable heaters. Make sure you keep them at least one metre from anything combustible (including curtains, bedding, etc.). Never leave them running when you’re either asleep or out of the house and keep small children away from the heat. For more complete safety tips, go to Canadian Standards Association.
Mark Mallet is a LEED Accredited professional consultant who writes about the green construction industry from his warm and cozy home in Nelson BC.
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