Hot air and the dash from gas:
The wind turbine is threatening to become this year's must-have accessory. The Conservative leader, David Cameron, and energy minister Malcolm Wicks have both pledged to install electricity-generating turbines on their roofs, and it can only be a matter of time before Madonna gets in on the act. The DIY chain B&Q this month started selling wind turbines and roof-mounted solar water heaters in an attempt to bring the technology to a wider audience, and to cash in on the current interest in this area. However, home generation is about much more than just wind turbines. The most suitable (and cheapest) technology for many homes is probably the solar water heater that will set you back around £2,000. Add in photovoltaic cells, ground source heat pumps, and solid fuel boilers, and you have a number of ways of making your home less reliant on the National Grid. To get an expert opinion on the costs involved and savings possible, we contacted Claire Bonham-Carter, director of sustainable development at London consultancy Faber Maunsell, who advises many of the UK's biggest house-building firms on how to use these technologies. She says home-owners should try not to review projects in pure financial payback terms but should focus on the wider benefits. "The heating and powering of houses accounts for almost a third of carbon dioxide produced in the UK. Installing one or more of these technologies will make a large reduction on the environmental impact of your home. There should also be a financial saving in reduced energy bills. Many housebuilders are being forced to install these measures by local authorities as a condition of planning approval. We will be seeing whole estates of houses with solar water heaters on the roofs." Before they even think of going down this route, she says, home-owners should make their home as fuel-efficient as possible. So assuming you have already got a well insulated home with low energy light bulbs and A-rated boiler and appliances, which technology would best suit your house? Despite the rash of recent publicity, wind turbines mounted on roofs are not suitable for all homes. Bonham-Carter says they work best on the tops of hills and away from trees. They do not work so well in urban areas where turbulence can hamper performance. Wind speeds of around 13mph are generally required and the bigger turbines will provide 71% of your electricity needs. The price of bigger units (£3,000) looks set to fall soon. Smaller units sell for £1,000. A black box converts the D/C power into usable electricity. They don't tend to last as long as other technologies. Solar water heaters have been around for many years and have proved reliable. The latest flat plate systems heat water which is supplied directly to a hot water cylinder in the house (can you accommodate one?) and installation is relatively simple. They work best on south-facing roofs (south-east or south-west will do) but it must not be shaded. They will not work with all types of combination boiler and those with hot feed washing machines save the most. Annual savings may well be higher than the £40 a year quoted. Photovoltaic cells are now so good that they will generate enough electricity to power a home even on gloomy days. They are expensive at £6,000 after grants but will last for years. Some have 25-30 year warranties. Positioning is also important, away from all shade. They also use a £200 inverter to change the current, which will typically last five to 10 years. They are more expensive, but their longevity make these a great investment. Ground source heat pumps are most suitable for homes off the gas network. They require a pipe network buried two metres underground and a heat exchanger to extract the heat (or cooling). They require electricity to operate. You get four units of energy out for each one put in and are best for newly- built homes with under-floor heating. Wood pellet boilers are more expensive (than gas) to operate but are carbon neutral. The cost of pellets looks set to fall in the future. Again, these are good for those away from mains gas. So what else do you need to consider? There are grants available for all of these technologies. The Department of Trade and Industry's low-carbon buildings programme gives financial help to homeowners, though in most cases you have to use an approved installer to get the money. Some local councils are also offering grants. For more information go to lowcarbonbuildings.org.uk . Householders planning to put a turbine or solar panels on their roofs will generally require planning permission, and those living in houses in protected areas may never get it. For the rest, it should not prove too problematic as councils are under pressure to up the number of homes using energy generated from renewables. Annual maintenance is not a big issue and the turbines and cells that generate power can be connected to the National Grid. This allows you to sell excess capacity to your power company. Lastly, installing these measurers is much cheaper if done in conjunction with other building work, and is very cost-efficient in new builds. Home-owners should also get back money invested when they come to sell up. 23.10.06