Double Glazing Savings Calculator
Calculate double glazing costs and annual energy savings by house type. See payback period.
Last updated: April 2026 · Source: Energy Saving Trust — Windows and doors
Total Cost
£3,600.00
Annual Saving
£160.00
Payback
22.5 years
20yr Net Saving
-£400.00
Disclaimer
This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.
How It Works
Double glazing replaces single-pane windows with sealed units containing two panes of glass separated by an insulating gap (typically 16mm of argon gas). This significantly reduces heat loss — a single-glazed window has a U-value of around 5.0 W/m2K, while standard double glazing achieves 1.4 W/m2K, and triple glazing reaches 0.8 W/m2K.
The cost of double glazing depends on window count, size, frame material (uPVC is cheapest at £300-£600 per window, timber £400-£800, aluminium £500-£900) and whether you need new frames or just replacement glass units. A typical 3-bed semi with 10 windows costs £4,000-£8,000 for full uPVC double glazing.
Energy savings from replacing single glazing with double glazing are estimated at £100-£200 per year by the Energy Saving Trust. The payback period is long (20-40 years on energy savings alone), so double glazing is best justified by combined benefits: energy saving, noise reduction, security improvement and property value increase.
Example: 3-bed semi, 10 windows, replacing single glazing
- Number of windows: 10 (mix of sizes)
- Frame type: uPVC (A+ rated)
- Average cost per window: £550
- Total installation cost: £5,500
- Estimated annual energy saving: £150
- Simple payback: 36.7 years (energy only)
- Property value uplift: £2,000-£5,000
Frequently Asked Questions
- What does the Double Glazing Savings Calculator do?
- Calculate double glazing costs and annual energy savings by house type. See payback period. All calculations are performed in your browser using official UK rates and thresholds.
- Does this reflect the current energy price cap?
- This calculator uses representative energy prices. The Ofgem energy price cap changes quarterly — check Ofgem's website for the latest cap level applicable to your region and payment method.
- Can I save money by switching tariff?
- Potentially yes. The energy market offers various fixed and variable tariffs. Use a comparison site authorised by Ofgem (such as Ofgem's own comparison tool) to check if switching could save you money.