Minimal Energy Use
Whether new or existing, ensure that your home uses less energy in the first instance. Insulate well and create an airtight envelope. The level of airtightness requires the appropriate ventilation.  Build tight and ventilate right.  Also, your level of boiler efficiency will substantially alter your heating usage.

Roof Insulation
270mm of Wool Type Insulation (nearly a foot thickness) would be the minimum recommendation for the insulation above the top floor ceiling.  If 400mm could be achieved that would be better.  Timber battens or plastic spacers can be fitted with chipboard over to maintain insulation thickness and a storage space over. Roof ventilation has to be considered for both new and existing houses.  If insulation is being fitted to an existing house, a ventilated tile may have to be fitted in some instances.

Windows
When deciding on windows, look at the U-value – the lower the better.  For existing houses, consider updating the glazing units only.  Many glazers and window manufacturer’s offer a glass replacement service.

Energy Saving Lighting
LED lights are an efficient solution.  The second option is compact fluorescent bulbs.  Energy efficient bulbs will last about 10 to 15 times longer and use between 10% and 20% of the energy of standard bulbs.

Renewables
Solar Panels, Wind Turbines, Heat Pumps and Biomass Boilers are regarded as renewables – they create energy from resources that are continually replenished.  As a general rule, unless your house is well insulated, with efficient glazed windows, energy efficient lighting and an efficient boiler, only then consider renewables.

Hot Water Cylinder
Consider installing a twin coil or triple coil cylinder when building a new house that will allow hot water to be heated from solar panels and a wood chip stove and not only oil.  If you do not have plans to install solar panels or a wood chip stove immediately, then you are allowing for the future.  All hot water tanks must have insulation, either integrated or in the form of a jacket

Energy efficient appliances
All white goods have an energy efficiency rating and the majority have an ‘A’ star.  For a very energy efficient house, a double or triple star would be required in order to use as little energy as possible.