Triple vs Double — Break-Even Calculator
Triple glazing costs more upfront but saves more on heating bills. The question is: how many years until the energy savings cover the extra cost? Pick your region and heating type to find out.
Assumes a typical 1.2m × 1.2m uPVC casement window (≈1.44 m² glazed area, 18m² total across an average 3-bed semi), 2,200 UK baseline heating degree-days, double U=1.2 W/m²K (A++), triple U=0.8 W/m²K (A+++), and 2026 retail energy prices. See Energy Savings Calculator for a more personalised estimate.
All regions × all heating types
Quick-reference grid showing break-even years for every combination:
| Region | Gas boiler (90%+ efficient) | Gas boiler (<90% efficient) | Oil | Electric (direct) | Heat pump (COP 3.5) | LPG |
|---|---|---|---|---|---|---|
| London / South East | 18.2 yr | 16.3 yr | 12.9 yr | 4.8 yr | 16.7 yr | 10.7 yr |
| South East | 15.9 yr | 14.2 yr | 11.3 yr | 4.2 yr | 14.6 yr | 9.4 yr |
| South West | 13.4 yr | 11.9 yr | 9.4 yr | 3.5 yr | 12.3 yr | 7.9 yr |
| Midlands | 12.1 yr | 10.8 yr | 8.6 yr | 3.2 yr | 11.1 yr | 7.1 yr |
| Northern England | 8.6 yr | 7.7 yr | 6.1 yr | 2.3 yr | 7.9 yr | 5.1 yr |
| Scotland | 9.1 yr | 8.1 yr | 6.4 yr | 2.4 yr | 8.3 yr | 5.4 yr |
| Wales | 9.0 yr | 8.0 yr | 6.4 yr | 2.4 yr | 8.2 yr | 5.3 yr |
| Northern Ireland | 9.2 yr | 8.2 yr | 6.5 yr | 2.4 yr | 8.5 yr | 5.4 yr |
How the calculation works
Annual energy savings = ΔU × window area × heating-degree-days × 24 ÷ 1000 × region multiplier
Annual £ savings = kWh saved × fuel price per kWh
Break-even = cost premium of triple ÷ annual £ savings
This is a simple payback calculation — it ignores energy price inflation, discounting, and maintenance costs (triple glazing is slightly heavier, but frames are similar). For a discounted cashflow model, use our Payback Period Calculator with the annual saving from Energy Savings Calculator.
Is triple glazing worth it for you?
- ≤5 years: Excellent — triple pays back fast. This typically happens with heat pumps or in colder regions (Scotland, Northern England).
- 5–10 years: Solid — worth doing if you plan to stay 10+ years. Most gas-heated homes in the Midlands and North fall here.
- 10–15 years: Marginal on energy alone — only if comfort, reduced draughts, or noise reduction are also priorities.
- ≥15 years: Unlikely to pay back before the windows need replacing. Consider high-spec double glazing instead; it costs less and still saves energy.
Next step
Energy Savings Calculator — personalise with your
actual window area, current glazing, and house size.
Payback Period Calculator — add energy-price inflation,
discount rate, and window lifetime for a full DCF analysis.