4. Solar water heating
A basic kit with solar panels, a heat-transfer system and a hot water cylinder costs Â£2,000 to Â£3,000 and could cover almost all your hot water needs in summer and half your needs through the rest of the year. You'll need 2sq m to 4sq m of south-facing roof and you'll probably be entitled to a grant of up to Â£400.
5. Wind turbines
Before you decide to generate your own electricity with a wind turbine, check with the manufacturer that you live in a suitable spot (exposed hilltops are ideal). B&Q now sells turbines from Â£1,500, but to be totally self-sufficient in wind-powered electricity you'll need a 2kW turbine (around Â£11,000). Government grants are available to help you. In many cases you'll also need planning permission.
6. Solar electricity
Also known as Solar Photovoltaic (Solar PV), this system converts the sun's energy into electricity. The panels come in a variety of shapes, including roof tiles, and should be attached to a south-facing roof. To produce a quarter of the electricity used each year by an average three-bedroom home you'll need to spend from around Â£7,500 but you should be entitled to a grant. You may also need planning permission.