The recent chilly weather means that many of us have had our central heating cranked up to full - and are dreading our gas and electricity bills as a result.
The average UK household is spending £1,066 a year on energy, and prices are expected to go up by an inflation-busting 5% next year.
Of course, there's a good chance that you can save money on your bills by shopping around for a better deal. But some lucky homeowners don't need to bother - and you could be one of them.
We look at six houses that are super-cheap or even free to keep warm.
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This unassuming two-bed semi is part of the new Layne Fields development in Christow, Exeter, in Dartmoor National Park. It's built to the Passivhaus standard, which means that it's air-tight, with a mechanical ventilation system that recovers heat. The developers say that it shouldn't need much in the way of extra heating at all, with annual heating and hot water bills expected to be in the region of £60 per year.
There are 18 two-bedroom houses and bungalows in the development, of which 14 are for rent and the remainder for sale; this one costs £164,000 for an 80% share from Aster Group.
On a large plot, this detached house has enough solar panels to supply its own electricity needs during the day - and to make a profit of £1,500 a year to boot. The income is guaranteed for the next 14 years under a government scheme.
There are four good-sized double bedrooms and two reception rooms. There's also a downstairs annexe that could be made completely self-contained and that could be perfect for elderly relatives, teenagers or for an office. The house costs £300,000 from Newman Estate Agents.
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If you're looking for a property a little further afield, there's this picture-perfect farmhouse near Belvès in the Dordogne. Fully insulated ad with double glazing, it has a central heating system powered by geothermal energy. Heat from the ground is recovered through a heat pump, keeping the five-bedroom property warm.
As well as the stunning main house, there are two gites and several outbuildings; there are shops, restaurants and a golf course nearby. The house costs £433,828 through Leggett Immobilier.
If you're on a wind-swept hillside, you might as well make the most of it - and this five-bedroom house near Doncaster enjoys free electricity thanks to a wind turbine and generator. Meanwhile, there's a solar heating system for the domestic hot water.
Formerly a pair of gamekeeper's cottages, the Edwardian property has plenty of original features scattered through its five bedrooms and four receptions. It has lovely views and is great for commuters, situated near junction 38 of the A1. It costs £395,000 through Bsmart Homes.
Cumberworth, West Yorkshire
Near Huddersfield, Upper Holme House Farm sits in glorious countryside with four acres of its own land - and with two extra houses included too. It's got exceptionally low running costs, thanks to solar panels that supply hot water. There's also a 6KW wind turbine with feed in tariffs guaranteed for the next 17 years with a net present value of £50,000, although this is available separately for £30,000. The house even has its own water supply from a spring with its own storage collection and UV filter system.
The main house has six bedrooms, and an adjoining barn and granary have also been converted to provide two one-bedroom houses. Everything's done up beautifully. The house costs £900,000 via Yorkshire's Finest.
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It's back to nature with this old schoolmaster's house in Carmarthen. It has wood/oil fired central heating - and, since it's self-sufficient in wood, it's very economical to run. It also has its own spring-fed water supply. In the five acres of organically managed land there's also a beautiful waterfall which, the agents point out, has potential for a hydroelectric installation. It has been assessed as being capable of producing 1KW of electricity.
As well as the five-bedroom main house, which has many original features, the new owner will get the original school building. This has planning permission for conversion to a three bedroom house. The property has a guide price of £310,000 with agent House Simple.