Free Eco Home Calculators

ROI Payback Calculator

1 min read Last updated 20 May 2026
Quick answer Most home eco upgrades have a positive lifetime ROI once you factor in 5-8% annual energy-price inflation. A typical solar install delivers around 200-300% ROI over 25 years; a heat pump (after the £7,500 BUS grant) delivers 100-200%; insulation can deliver 400%+ on the cheapest measures.

The ROI & Payback Calculator works out the lifetime return on any home eco upgrade — solar panels, heat pump, insulation, windows or boiler. It accounts for grants, energy-price inflation over the product's lifespan, and a property-value uplift estimate. Use it to compare projects on a like-for-like basis.

ROI & Payback Calculator

Calculate the return on investment and payback period for any eco upgrade.

See 20 real-world examples

Each link below runs this calculator with real UK city and property inputs and publishes the exact computed savings, payback time, install cost and CO2 figures.

Browse all calculator examples →

How this calculator works

Net cost is install cost minus grant. Cumulative savings are calculated year-by-year applying annual energy-price inflation: year-Y saving = base-saving × (1 + inflation)^(Y-1). Adjusted payback is the year in which cumulative savings ≥ net cost. Total ROI is total savings minus net cost, divided by net cost. Property value uplift is conservatively estimated at 4% of install cost based on RICS guidance.

Sources & references

Frequently asked questions

What energy inflation rate should I use?

The Bank of England 2% target applies to general inflation, but energy prices have averaged 6-8% real-terms growth since 2020 due to gas market volatility and decarbonisation costs. 5% is a reasonable central estimate; 3% is conservative; 8% is what you'd see in another energy crisis.

Is the property value uplift realistic?

The 4% figure is a conservative average from RICS reports. Specific upgrades vary: a cosmetic window upgrade adds little; an EPC band jump (D to C, or C to B) adds 1-3%; fitted heat pump and solar can add 3-5% in eco-conscious markets but is sometimes neutral or negative in older areas.

Why does payback shorten when I add inflation?

Each year your savings grow with energy prices. So you "earn back" the install cost faster in real terms. At 5% inflation, the year-10 saving is 55% larger than year-1, and the year-25 saving is 240% larger.

What's a "good" ROI for a home upgrade?

Anything above 100% over the product lifespan is a financially positive project. Loft insulation typically delivers 400-800%; solar PV 200-300%; heat pumps 100-200%; windows often break even (the value is comfort, not cash). Payback under 10 years for a 25-year product is excellent.

Tool: ROI & Payback Calculator. Last reviewed: . Figures based on Ofgem price cap, gov.uk grant guidance, and Energy Saving Trust advice. Verify scheme eligibility with your installer before commissioning work.