Calculator
Insulation ROI Calculator
Compare attic insulation, wall insulation, windows, draught proofing, and other upgrades using simple homeowner-friendly numbers.
Estimate simple payback before committing to insulation work
Insulation projects can improve comfort and reduce heat demand, but the financial return depends on installation cost, grant support, workmanship, and current heating bills.
This calculator gives you a simple payback view so you can compare common upgrade types before getting detailed surveys or contractor quotes.
How the formula works
Net upgrade cost equals upgrade cost minus any grant amount. Annual saving equals current annual heating cost multiplied by the expected saving percentage.
Simple payback equals net upgrade cost divided by annual saving. Ten-year saving subtracts the net upgrade cost from ten years of estimated bill savings.
Example calculation
If attic insulation costs GBP1,500, receives no grant, and saves 12% of a GBP1,400 heating bill, annual savings are about GBP168.
Simple payback is roughly 8.9 years. The comfort improvement may still matter even if bill payback is not instant.
United Kingdom assumptions
Currency: GBP. Electricity: Check current official sources. Gas: Check current official sources. Heating oil: Check current official sources.
Last reviewed: 2026-04-27. Confidence: medium. Prices are not pre-filled because supplier tariffs and price caps change. Enter your current unit rates from a bill.
Net upgrade cost
£1,500
Annual savings
£210
Payback period
7.1 years
10-year estimated savings
£600
Often one of the quickest-payback measures in lofted homes.
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