Cutting heat loss is the least glamorous way to save energy and usually the best value. A £20 brush strip or an empty loft filled can pay back far faster than any gadget. These guides rank the jobs by cost and savings, using Energy Saving Trust and U.S. DOE figures, and flag the mistakes (blocked vents, damp) that turn a good job into a problem.
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Every figure in these guides links to its source and shows when we last checked it. Read how we research, or tell us if something has changed.