Traditional home heating systems have evolved over the years. To help potential buyers, this article will provide you with the tools you need to make a sensible, cost-effective purchase of energy efficient space heaters, no matter the primary heating method used in your home, RV, vacation cabin, apartment or business.

The Universe of Energy

But first, a little background before getting into the details of energy efficient space heaters.

There are only seven identified forms of energy exist in the universe:

  1. Chemical — The energy trapped in chemical bonds, like the structure of firewood or coal
  2. Radiant — Energy radiating from a single source, like the sun
  3. Electrical — The energy of moving electrons
  4. Sound — Energy moving by waves, disturbing their environment
  5. Thermal — The energy of the movement of atoms and molecules in substances
  6. Mechanical — The energy of motion; potential and kinetic energy
  7. Nuclear — The energy holding nuclei together in atoms

Electrical energy, a typical source of power for space heaters, is a secondary energy; it often depends on releasing chemical energy from fossil fuels, which is then converted to mechanical energy (spinning a turbine), which converts to electricity. According to the U.S. Energy Information Administration (EIA), in 2016:

  • Oil (a fossil fuel) provided only one percent of America’s electrical energy
  • 15 percent came from renewable energy sources (wind, solar, biomass, hydro and geothermal)
  • Around 20 percent came from nuclear power
  • Coal (a fossil fuel) provided around 30 percent
  • Natural gas (a fossil fuel) provided around 34 percent

Use of some fossil fuels has declined in recent years as coal becomes more expensive compared to costs of natural gas and renewable energy.

Anyone using a space heater powered by electricity can take some comfort in knowing a complete mix of fuels and energy sources generates that power. Some homeowners can further control their sources of electricity through electrical provider choice, an option available in 18 states and the District of Columbia, according to Electric Choice.

This means environmentally conscious persons in one of those 19 localities can elect to use renewable energy to power the electric portable space heater for their personal comfort while also reducing their carbon footprint, lowering greenhouse gas generation and reducing our country’s dependence on foreign energy sources.


Homes, senior centers, hunting lodges, fishing cabins, RVs and businesses typically use one of four methods to provide heat throughout a structure:

  1. Furnace — In a furnace, hot air created by burning natural gas or liquid propane or by converting electricity to heat is blown through ducts while return ducts pull in stale room air for reheating
  2. Boiler — A boiler converts oil, natural gas, liquid propane or biomass to heat, which is transferred into hot water, which is piped through baseboards (hydronic heating) or radiators
  3. Heat pump — Heat is drawn from the air (air-source heat pump) or ground (ground-source heat pump) and transferred into the indoor air space
  4. Wood furnace — In recent years, a trend has developed to build outdoor, wood-fired furnaces that convert chemical energy in wood into heat, which is transferred into the home using the house’s existing technology

For each of these heating methods, various yardsticks have been created to allow manufacturers, governmental agencies and buyers to compare products. For example, furnaces are measured using Annual Fuel Utilization Efficiency, or AFUE.

You need not worry about how this yardstick was created or exactly what it measures, so long as you compare a furnace to a furnace. A high AFUE furnace may be 98 percent efficient, meaning 98 percent of the heat potential of a fuel is delivered to you as heat, rather than wasted up a chimney or as another form of energy (light or sound — a crackling wood fire in a wood stove or fireplace is romantic but wasteful).

The basic measurements of the various heating methods are your key to realizing energy savings with energy efficient space heaters:

  • Watts — The transfer of one joule per second, watts are handy measures of power and are often applied to electrical appliances, like portable space heaters
  • KWh — Kilowatt-hours are power consumption equal to 1,000 watts in one hour, so a 1,200-watt personal space heater run for one hour of relaxing, welcoming warmth uses 1.2 kWh
  • AFUE — Annualized Fuel Utilization Efficiency is useful for measuring furnaces and boilers
  • HSPF — Heating Seasonal Performance Factor is appropriate for measuring heat pumps
  • COP — Coefficient of performance measures heat pumps
  • BTUs — British Thermal Units have been around a long time, but are still a useful way for heat engineers to compare heat production across sources; 1000 BTUs per hour is approximately 293 watts

Measuring Energy Efficient Space Heaters

You can compare the energy efficiency of a portable space heater and your home’s main heating plant. We must begin by accepting, as the EPA says, that individual heaters are not as energy efficient as HVAC systems. Portable space heaters are not a multi-room solution to an inefficient or older heating plant.

The EPA points out, though, that space heaters can efficiently provide heat for a given space while allowing the rest of the house to use less power. This is their unique advantage: gentle heat where it is wanted and where it does the most good.

To make your own comparison, identify what kind of heating system you use (furnace, boiler, heat pump, wood furnace) and learn its efficiency measure. For example, your heat pump when installed may have had an HSPF rating of 8. This measurement would have come from typical numbers such as these:

  • 120 million BTUs delivered in a season using 15,000 kWh = 120,000,000/(1,000 (15,000 kWh) = 8

You can then determine by what amount a portable space heater will be less efficient than your home’s heating method; the greater the discrepancy, the greater your cost to run the portable heater.

In our example, a 1,500-watt portable space heater is 1.5 kW; run for one hour it uses 1.5 kWh and produces 5,118.2 BTUs for the hour. This produces a (theoretical) HSPF of 3.4 for the hour you use the heater. The portable space heater is roughly half as efficient as your home’s heat pump.

You will not make up a portable space heater’s minor inefficiency in a small area by increasing your main heat plant’s set-point (the temperature to which it will raise the entire space’s air). Indeed, your savings comes from having a small, portable heater in a small space while your entire inhabited space is kept at a lower temperature.

In our example, running the heat pump with HSPF of 8 so that it warms the entire space to, say, 72 degrees Fahrenheit, will cost you a significant bump in power usage when you could have used a portable space heater (at roughly half the efficiency of your heat pump) for a single room, allowing the rest of the house or office to drop to a set-point of 65℉.

A note of caution: These theoretical figures of a portable space heater’s HSPF versus your heat pump’s HSPF should not be used by themselves to decide if a portable space heater is right for you. The true comparison is a bit more involved.

A concern among buyers of personal space heaters is the nagging feeling that the heater, not as energy efficient as their heating, ventilation and air conditioning (HVAC) system, is costing a lot of money to operate. This is an extremely complicated calculation to make, for three reasons:

  1. Embedded energy costs are nearly unmeasurable in fuels like home-delivered fuel oil — the energy needed to produce the fuel, store it, deliver it and use it
  2. Adjustments to your whole-house temperature for the sake of feeling more comfortable in a single room may result in greater energy consumption than keeping the whole house temperature low while using slightly more electricity in the single room
  3. You may not be in a position to precisely measure the energy efficiency of your home, apartment or business heating system

Once you understand that you are using a slightly less efficient heater to heat a much smaller space than an entire RV, office or home, you can properly evaluate its energy efficiency. One way to think of it is how effectively it produces heat where you want it.

Portable electric heaters are overwhelmingly popular in America as secondary heat sources, according to the EIA, with some 47 percent of homes using them. All other types (wood-burning stove, wood-burning fireplace or natural gas fireplace) are distant also-rans.

A portable space heater in a room is actually close to 100 percent energy efficient for the task assigned to it because its express purpose is to change electricity into heat, which it does extremely efficiently. Except for a tiny bit of energy lost as light energy from any glowing heat element, every bit of electrical energy converts to bone-soothing, personalized heat.

Energy Efficient Space Heaters for a Particular Space

To buy an energy efficient space heaters, you must know the square footage of the room you intend to supplement with the heater. Measure length times width to get the square footage. Then multiply that number times ten to get the wattage needed for the room:

  • A 10 x 12 room is 120 square feet and needs 1,200 watts from the portable space heater

Wattage, though, is only part of the calculation. Multiply the wattage times 3.413 to get BTUs delivered to the exact place you want heat:

Buy a portable space heater for a particular room, so you neither under-heat nor over-heat the space. This helps avoid wasted money on increased electrical use or wear and tear from short-cycling the heater (making it go on and off quickly).

Buy For Maximum Efficiency

A portable heater of 1,500 watts, such as the NewAir Portable Ceramic Space Heater, will quickly heat a room size from 150 square feet up to around 400 square feet, depending on factors like ceiling height, number of windows and the furniture in the room.

It does the job efficiently, too, using both a timer and an adjustable temperature setting with a range from 41 to 95 degrees Fahrenheit. By choosing a temperature perfect for your personal conditions — say, 72 degrees Fahrenheit — you can leave the rest of your home, office or RV at a more energy-efficient setting of 66 degrees Fahrenheit while still feeling comfortable.

Special Needs

Several populations of users of space heaters have special needs making portable, personal space heaters excellent methods of warming a particular space:

  • Infants and toddlers
  • Elderly family members
  • Convalescent patients or those with weakened constitutions
  • Bedridden individuals

For these people, physical activity will necessarily be curtailed. What typical children and adults feel as comfortable indoor temperatures — somewhere between 66 and 72 degrees Fahrenheit — will be unusually cold to these special populations. A portable space heater can provide the pinpoint warmth they need to not only shake the chill but feel genuinely comfortable.

Obviously for infants, toddlers and family members who cannot care for themselves, no portable space heater should be left unattended. Yet while spending time with these individuals, you can economize in the rest of the home by keeping your HVAC system at a low set-point. By turning the portable space heater off when you leave the room of this beloved family member, you can ensure steady, comforting heat and safety.

How to Select an Energy-Efficient Portable Space Heater

We have seen that no personal space heater will be capable of rivaling a whole-house HVAC system’s seasonal energy efficiency. Yet we have also seen that the personal flexibility, small-room economy and pleasant, individual comfort are worth the slight decrease in energy efficiency. Still, you can shop for the most efficient heater using a few simple metrics:

  1. Measure for a specific room space
  2. Do the math and buy for the wattage needed for that space alone
  3. Buy energy efficient space heaters with safety features and economizing features in mind, such as temperature choice and timers
  4. Buy the most modern, recently manufactured heater — You save nothing in energy costs by retaining older models; their embedded costs have been repaid many times over and they are now highly inefficient compared to current models, such as the NewAir AH-470 Flat Panel Micathermic Space Heater, or the even more modern NewAir Portable Ceramic Space Heater
Safe, modern energy efficient space heaters, combined with an efficient and wisely used main heating system, can provide soothing, pinpoint heat in a personal way while still saving money and conserving resources.


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