Heaters: oil column vs gas vs electric radiant vs electric fan

G Magazine

They're a must-have for cold winter nights, but which portable heater generates the most sustainable warmth?


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While Jack Frost works his winter magic, we're snuggled up in front of the heater. If your home isn't fitted with permanent central or single-unit heating, portable warmth is a winter essential. But staying warm and toasty can generate a significant eco-footprint – depending on where you live, it accounts for up to 50 per cent of household energy use – not to mention fry your brain with all the different types of heaters lining the shelves at your local appliance store.

Advocates of oil column and radiant heaters swear by their quiet, cosy heat, while fans of the ubiquitous fan heater are instantly gratified by its immediate warmth. At the other end of the fossil fuel spectrum, gas heater converts are addicted to lower utility bills. Yet when it comes to matters of environmental warming, it's hardly a clear-cut decision as to which is the greenest choice.

Warming up

A portable heater is a global appliance, with the original parts manufacturers located all over the world. Generally, these parts are manufactured out of a range of metals – primarily steel - plastics, ceramics, glass and microelectronics.

All of these materials bear an environmental load. Steel production produces about two tonnes of CO2 per tonne of steel, and while PVC (the type of plastic used in the outer shell of a fan heater) is the least energy intensive of all thermoplastics, 1kg of PVC has a carbon footprint of approximately 4.1kg of CO2.

Gas and oil column heaters are the biggest of the bunch, so their material impact is the most significant. But transporting your heater to a retail outlet is also environmentally draining, and it's here that the oil column variety loses further green points.

“An oil filled storage heater would be the least desirable in terms of transport and distribution because of the weight – smaller products are better because they're easier and cheaper to ship,” says Dr Miles Park, industrial design program director for the Faculty of the Built Environment at UNSW.

In the hot seat

As with most household appliances, using the product generates a greater eco-footprint than the energy required in its production. So the efficiency of your heater is far more significant than its size, materials or how far it's travelled to your home. And that efficiency depends very much on the area you're heating and how quickly the heat is required.

Radiant heaters emit heat via infrared radiation from their red hot bars, warming people and objects in the room almost instantly without directly warming the air. Since they don't try to heat a large volume of air, electric radiant heaters avoid the high energy losses that occur when convection heaters (which heat a room by filling it with warm circulating air) are used in large or draughty spaces. A heater that only uses radiant heat won’t efficiently warm the air in a room, so is best used as a personal heater.

Similarly, electric fan heaters provide instantaneous heat but combine an electric element with a fan to blow warm convective air around a room. They are cheap to buy but often noisy and only really effective in small areas like bedrooms and studies, reports Energy Australia.

Oil-filled column heaters use electricity to heat the oil that is sealed inside their 'fins'. This heat is then transferred to the steel casting which circulates the warmth through natural convection (without a fan) and also emits some radiant heat. Because of this, oil heaters take time to heat a room but are particularly useful for long or unattended use, such as overnight in a bedroom.

But in order to supply power to any of these electric heaters, we've wasted an awful lot of energy along the way. Approximately 84 per cent of electricity in Australia is derived from burning coal, which generates a whopping 170 million tonnes of CO2 every year.

The alternative? Look below the ocean floor to gas. Only 20 per cent of the energy produced by burning coal actually reaches a heater, compared to 90 per cent of gas combustion energy. According to consumer association Choice, unflued portable gas heaters are very efficient, producing only a quarter to a third of the carbon dioxide of an equivalent electric heater.

However, when gas is burnt air pollutants and water vapour are also produced. Permanently fitted flued gas heaters vent these nasties outside the home through a chimney or flue, while unflued gas heaters release them directly into the home. Ventilation is a must, which means they're unsuitable for bedrooms and bathrooms. Portable gas heaters are not permitted to run on natural gas in some regions such as Victoria.

Cooling down

Theoretically, all portable heaters can be recycled, although the trapped oil in column heaters means they're likely to be the most difficult to pull apart. But in reality, Australian industry lacks the infrastructure to make this happen.

There are some signs of progress, with the introduction of Product Stewardship Australia, a not-for-profit, industry-led organisation that aims to help “recover and recycle electronic and electrical products in an environmentally sound manner”. As yet heaters aren't on the list of targeted industries – televisions and computers are top priority – but the organisation is still in its infancy.

The verdict

So which portable heater emits the greenest warmth? If regulations allow and your space is appropriate, unflued gas is the top performer – while it's a lot more expensive to buy than electric varieties, it's much cheaper to run as it's very efficient and boasts the lowest greenhouse gas emission count.

Choose a heater with a thermostat and six-star energy rating (which equates to 91 per cent efficiency) and you've got yourself a truly green cold weather companion.

But if regulations in your local area don't permit the use of unflued gas heaters or you're concerned about the health risks, it depends on your situation as to which winter warmer is best. And just to make the decision a little more confusing, it's not a government requirement for portable electric heating products to have an energy star rating.

If you need to heat a small, well-insulated room for a long period of time, choose oil column. For bathrooms or personal use in larger draughtly spaces, radiant heat works most efficiently. Fan heaters are suited to small areas for short periods.

Reduce the need for too much heat with a woolly jumper, adequate insulation, sound draught proofing and window coverings and come spring you'll be accustomed to a healthy shade of green around your home.