Insulation
The greatest savings will be made if you currently have no loft insulation. From nothing to 270mm will cost about £500, but could save approximately £110 in its first year.
Increasing the depth of your insulation and covering joints, e.g. laying new insulation across existing insulation could further reduce your carbon emissions.
If you have cavity walls these can be filled relatively cheaply, on average about £500. This could reduce your heating costs by about 15%.
External wall insulation can be added if you don’t have a cavity. For an average three bed semi this will cost around £2,000, but could save about £300 a year from your heating bills and towards 3 tonnes of CO2 per year.
Internal insulation is a good option if you cannot change the exterior of your home. Although you will lose some space internally you will only need to insulate exterior walls (only front and back for a terraced home) and newer versions are only a couple of inches thick. Thinner versions are available with lower insulating properties.
Fitting under-floor insulation is particularly relevant in old homes. Those floorboards that are loved so much were designed to be covered. Exposing and stripping them lets in large draughts. Gaps between the boards can be filled or insulation can be fitted under the floor.