Window & Door ROI Calculator

Calculate energy savings and payback period from window and door replacement

Window & Door ROI Calculator

Calculate savings and payback period for window and door replacement

Current Setup

Planned Upgrade

Understanding U-Values & Energy Efficiency

Lower U-values mean better insulation and less heat loss through windows and doors

Poor

U > 3.0

Old single glazed windows, uninsulated doors - high heat loss

Fair

U: 2.0-3.0

Standard double glazed windows, basic insulated doors

Good

U: 1.0-2.0

Low-E coated windows, well-insulated doors

Excellent

U < 1.0

Triple glazed windows, passive house standard

Smart Investment Tips

Maximise your return on investment with these professional recommendations

Timing Matters

Replace during renovations or when existing windows/doors need repair anyway

Prioritise Impact

Focus on north-facing windows and entrance doors for maximum energy savings

Check Incentives

Many regions offer rebates for energy-efficient windows and doors

  1. 1

    Measure Window Area

    Measure each window (width × height) and add together for total area. Count number of windows and doors needing replacement. Include all single-pane or damaged units.

  2. 2

    Check Current U-Value

    Identify existing window type: single-pane (U-5.0 to 6.0), old double-pane (U-2.5 to 3.0), or newer windows (U-1.5 to 2.0). Check for ENERGY STAR label or manufacturer specs.

  3. 3

    Select Upgrade Type

    Choose replacement windows: standard double-glazing (U-2.5), low-E double-glazing (U-1.5 to 2.0), or triple-glazing (U-1.0 to 1.5). Better windows = higher cost but greater savings. Consider secondary glazing for listed buildings (£200-£400 per window).

  4. 4

    Get Installation Quote

    Enter total cost including windows, doors, installation labour, disposal, and finishing. Typical UK prices: £400-£1,200 per window, £1,500-£4,000 per door depending on size and glazing type. uPVC cheapest, timber/aluminium more expensive. Get 3 quotes for accurate pricing.

  5. 5

    Review Savings and Payback

    Calculator shows annual energy savings and payback period. Consider: <10 year payback = good investment, especially for single-pane replacements. Factor in comfort improvements, noise reduction, increased home value, and condensation elimination.

Pro Tip: Use Ctrl+Enter to calculate quickly, or Ctrl+R to reset the form.

Frequently Asked Questions

New energy-efficient windows typically save 10-25% on heating/cooling costs. For homes spending £160/month on energy, that's £200-500/year savings. Windows cost £300-800 each installed, so payback is 8-20 years. Biggest savings come from replacing single-pane windows with triple-pane or low-E double-pane.

U-value measures heat loss through windows - lower is better. Single-pane: 5.0-6.0 (terrible), standard double-pane: 2.5-3.0 (OK), low-E double-pane: 1.5-2.0 (good), triple-pane: 1.0-1.5 (very good), high-performance: 0.5-0.8 (excellent). Target U-1.5 or lower for cold climates.

Prioritise: 1) Single-pane windows (biggest savings), 2) North-facing (coldest), 3) Large windows (most heat loss), 4) Windows with visible damage/draughts. Replacing worst 30-50% of windows captures 60-80% of potential savings at lower cost than full replacement.

Secondary glazing costs £150-300 installed vs £500-1200 for full replacement. It improves U-value by ~0.5-1.0 and extends existing window life 10-15 years. Good option if: existing windows in good condition, budget limited, listed building restrictions. Drawback: less effective than new windows, requires maintenance, somewhat less attractive.

Replace in this order: 1) Single-pane windows (U-5.0+, huge savings), 2) North-facing windows (coldest exposure, 30% more heat loss), 3) Large picture windows (greatest total heat loss), 4) Damaged/leaking windows (air infiltration wastes energy), 5) Bedroom windows (comfort + energy). Start with worst performers for maximum ROI.

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