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Insulation ROI Calculator

Compare attic insulation, wall insulation, windows, draught proofing, and other upgrades using simple homeowner-friendly numbers.

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Published: 2026-01-01

Last updated: 2026-04-28

Last reviewed: 2026-04-28

Confidence: medium

Page review status

Written by: HeatWise Home Editorial Team

Reviewed by: Editorial review by HeatWise Home

Review status: Internally reviewed for clarity, source consistency, and calculation assumptions.

Expert review: Not currently externally expert-reviewed.

Last updated: 2026-04-28

Last reviewed: 2026-04-28

Confidence: medium

Sources:

External expert review: HeatWise Home does not currently publish named external expert reviewers. We are working toward adding independent review from qualified retrofit, heating, or building-energy professionals. Until then, users should treat our calculators and guides as educational planning tools and confirm decisions with official sources and qualified installers.

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.

Helpful next step

See formulas, assumptions, and limits behind each estimate.

Read our calculator methodology

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: £0.25 per kWh. Gas: £0.06 per kWh. Heating oil: £0.11 per kWh.

  • Planning ranges: Electricity GBP 0.22-0.34 per kWh (Ofgem regional cap spread and available tariffs); Gas GBP 0.05-0.11 per kWh (Ofgem cap benchmark and regional/tariff variation); Heating oil GBP 0.09-0.13 per kWh equivalent (kerosene supplier tracking, delivery-size and season dependent).
  • Last checked: 2026-04-28. Confidence: medium.
  • Sources: Ofgem energy price cap and market data, GOV.UK Boiler Upgrade Scheme, MCS standards and UK building fabric guidance.

Caveat: prices vary by supplier, tariff, region, standing charge, and usage. Electricity/gas benchmarks align with Ofgem's 1 April to 30 June 2026 cap context (24.67p/kWh electricity and 5.74p/kWh gas GB average, Direct Debit) and broader tariff variation. Heating-oil range uses UK supplier-tracked kerosene pricing converted to kWh-equivalent planning values.

View calculator methodology

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.

Calculators on this site are estimates only. Always get a professional heat loss survey and verify current grant rules, tariffs, and product suitability before making purchase decisions.

Insulation ROI FAQs

Energy prices, occupant behavior, and workmanship all affect the true return from insulation upgrades.

Helpful next step

Adjust fuel prices, SCOP, grants, and costs using your own numbers.

Estimate your heat pump payback

Related tools and guides

Home Energy Cost CalculatorHeat Pump Sizing CalculatorBest Home Upgrades

Methodology and assumptions

Review formulas, SCOP/COP context, fuel price assumptions, and limitations before relying on results.

Read calculator methodology

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  • There is no obligation to proceed after you submit this form.
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  • Your data is handled according to our Privacy Policy.

What happens next:

  1. We review your question or quote request.
  2. We may reply directly or ask for missing details.
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If we suggest a partner

Where we suggest a partner, we aim to prioritise relevant, reputable providers or installers. We do not recommend proceeding without checking credentials, quotes, warranties, and official grant requirements.

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Occasional homeowner-friendly notes on heating costs, grants, insulation, and practical ways to lower bills.

Helpful next step

Pressure-test savings assumptions before committing to upgrades.

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