The cheapest energy is the energy you don't waste. This guide brings together our advice on insulation, draughts, ventilation, EPC ratings and generating your own power, roughly in the order most homes should tackle them, so you spend money where it makes the biggest difference first.
Last reviewed: October 2026
UK insulation types compared Mineral wool, foam or boards, and which suits your loft, walls or floor.
Loft insulation savings: what a top-up really saves Costs, savings and the mistakes that cancel them out.
EPC ratings explained What your band means for your bills, and what moves it.
For most homes the order is simple: stop the draughts, top up the loft, then look at the walls. Loft insulation is usually the cheapest and quickest win. The commonly recommended depth for mineral wool is around 270mm. Wall insulation needs more care, because the wrong product in the wrong wall can cause damp.
Draughts are often the cheapest heat loss to fix, and a weekend of draught-proofing can make a room feel noticeably warmer. Windows are a bigger investment, and in period or listed homes the rules on what you can change may be stricter.
Replacing every window? See window replacement costs in our building work guide.
A well-insulated home still needs to breathe. As homes get more airtight, moisture from cooking, washing and breathing has fewer ways out, and condensation and mould follow. Ventilation is the other half of insulation.
For rising and penetrating damp, see our drainage, plumbing and damp guide.
An Energy Performance Certificate rates your home from A to G and lasts for ten years. You need a valid one to sell or let a home. The report also lists recommended improvements, but some move your score far more than others.
Once the fabric of your home is sorted, the next savings come from how you use energy and how you pay for it.
For heating controls and settings, see our heating and heat pumps guide.
Generating your own electricity can cut bills, but the payback depends heavily on your roof, how much power you use at home and your tariff. Since the Feed-in Tariff closed, exported electricity is paid through the Smart Export Guarantee, at rates set by each supplier.
Home+ stores your EPC and insulation guarantees in your document vault, reads the expiry date for you, and keeps a record of every improvement you make, which is useful when you come to sell.
Create your free Home+ account to store your EPC and guarantees and keep a record of the work you've done.