Insulation Payback Calculator
Enter your yearly heating cost and pick an upgrade. The calculator gives the annual saving, payback period, the 10-year net after costs, and the CO₂ cut - with the true order of operations spelled out.
Window-sales pages sell glazing as the insulation king. The honest payback ranking is draft-proofing, loft, walls, then windows - and this calculator prices all four so the sequence is visible instead of sold.
How to use
- Use your actual annual heating spend (the heating cost calculator estimates it if you do not know).
- Pick the upgrade you are considering; defaults are typical installed costs before any subsidy.
- Compare payback years across options - then check national grants, which move every figure left.
Frequently asked questions
Which insulation upgrade pays back fastest?
Draft-proofing: a weekend and a few hundred units of materials against 8% of the bill - often a one-year payback. Loft insulation is the best professionally-installed job; walls are the biggest absolute saving.
Why do windows rank last for savings?
Glass upgrade costs dominate: thousands to install against roughly 10% of heating bills, pushing payback past a decade. People still rightly replace windows - for comfort, noise and resale - but the savings are the alibi, not the reason.
Do subsidies change the ranking?
They change the numbers, not the physics: grants on loft and wall schemes can halve payback, and some regions cover draft-proofing entirely. Always price the grant first - the ranking only shifts when a subsidy is that large.
Can insulation cause damp?
It can, done badly: walls that stop drying inward without ventilation or breathable materials trap moisture. This is the corner where the cheapest quote becomes the expensive one - ask any installer explicitly how the wall will still dry.