Woodburners head off heat pumps as the cheapest form of heating; unflued LPG heaters are the most expensive. Natural gas is the cheapest form of central heating – just ahead of pellet burners.
Firewood
A woodburner is still the cheapest way to heat your home – especially if you can get free firewood. We’ve used prices for pine firewood in our Fuel prices compared table as it was the cheapest and most widely available type in our January survey of firewood prices.
We haven’t calculated the cost of burning wood in an open fire. Open fires are inefficient (heat is lost up the chimney) and cause massive pollution for the heat they do produce.
Tip: Buy early – during spring or early summer – and phone around for prices. We found some good deals in our firewood survey.
How clean?
Along with wind and hydro, wood is one of the few sustainable carbon-neutral home-heating options. But to get the most heat (and the least pollution), it must be burned hot and in a specially designed firebox. The firewood must also be dry and the pieces not too big (less than 11cm in diameter).
Some woodburners can be used to heat wetbacks but this reduces their efficiency and may also overheat the water.
More information
Wood pellets
Wood pellets are used in pellet burners and also in boilers for central heating.
Pellet burners cost more to run than woodburners but they have their advantages. They produce less atmospheric pollution and the pellets are carbon neutral because they’re made from waste wood (compressed sawdust and wood shavings).
Pellet-fired central heating has a clear environmental advantage over other types of central heating fuel – it uses a renewable resource.
Tip: Our price checks in Auckland and Wellington found big variations, so phone around. In Christchurch wood-pellet prices were much lower and varied less. Make sure you’re comparing like with like – the pellets are sold in 15 kg or 20 kg bags. If you’re close to a pellet mill and can buy in bulk, you’ll be able to get a lower price.
More information
Electricity
Heat pumps are one of the cheapest heating options to run. They can be retrofitted – but they must be the right capacity for the house and they must be installed properly.
Discounted night rates make nightstore heaters and underfloor heating comparatively cheap, although you will need a separate meter (which would be an extra cost).
Portable heaters are the most expensive form of electrical heating. For modern well-insulated homes we recommend convection or oil-column models because the warmth is likely to circulate. For poorly insulated older houses with high ceilings, radiant heaters are likely to be more effective – you can feel their heat more directly. However, they shouldn’t be used in bedrooms or around young children.
Our cost calculations for electricity come from our PowerSwitch website – there was a big difference between the highest and lowest prices for each type of heating.
How clean?
Our electricity comes from a combination of renewable (wind, hydro and geothermal) and non-renewable (gas and coal) sources - so it's only a semi-clean fuel. But in your home, nothing is cleaner. Despite the inexorable rise in the price of electricity, electric heating provides a clean and easy way to heat your home.
More information
- Compare electricity prices on Consumer Powerswitch
- Choosing an electric heater
- Convection heaters
- Heat pumps
Natural gas
It’s cheaper to run your flued heater or central heating on natural gas rather than LPG. Unfortunately, reticulated (piped) natural gas is available only in the North Island.
Prices for natural gas can fluctuate, as they do for LPG and diesel. They’re world commodities and subject to rapid price changes that are out of the householder’s control.
Our cost calculations for natural gas come from our PowerSwitch website.
Tip: “Dual fuel” discounts for buying gas and electricity from the same provider are generally cheaper than paying for gas alone.
How clean?
Natural gas is clean-burning for pollutants, but it's a fossil fuel. Burning it adds the greenhouse gas carbon dioxide to the environment.
More information
LPG
Prices for the 45kg cylinders of LPG delivered to your door include the cost of delivery, so people in rural areas pay more for their gas. As well there’s a rental charge. Flued heaters and central heating that use LPG cost more to run than natural gas heating.
Running an unflued heater on 9kg bottles is the most expensive way of using LPG. It also presents a health and safety hazard. Unflued gas heaters create condensation and produce CO2. If a fault develops the heater may emit carbon monoxide (a poisonous gas). This can build up in a room and pose a significant health risk to children, pregnant women, elderly people and those with asthma or heart disease. High levels can be fatal to anyone. For this reason an unflued heater should only be used in rooms with good ventilation and should never be used in bedrooms.
Tip: We collected prices for “swappa” 9kg bottles – you pay for the first bottle you use but after that you simply swap your empty bottle for a full one. This means you don’t have the expense of having your bottle checked every 10 years as required by law.
How clean?
Like natural gas, LPG is clean-burning but adds carbon dioxide to the environment.
More information
Diesel
Diesel boilers heat water for use in water-filled radiators or under-floor heating.
Running your central heating on diesel is cheaper than using LPG – so in the South Island, where LPG is the only gas available, diesel is the better option for central heating.
However, diesel is more expensive than (reticulated) natural gas. So in the North Island, natural gas is the cheaper option.
When we surveyed in February 2011 diesel prices had risen by 23 percent over the past year. Since then they have spiked even higher – this has added an extra cent per kilowatt hour to their running cost.
How clean?
Now that we have low-sulphur diesel fuel, it's relatively clean in terms of pollutants. But it does come from non-sustainable fossil fuel and adds to carbon dioxide emissions.
The sun
It's free, and the most environmentally-friendly home heating option available. You'll need large north-facing windows to allow the sun to shine in during the day, a large thermal mass such as a concrete floor to store the heat, and insulation so the heat isn't lost too quickly at night. And you'll probably still need other heat sources for the coldest days.
If you're designing a new home, incorporating some passive solar heating into the design may not cost very much at all. It may also be possible to include some solar features when you're renovating, but it's harder.
More information
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