By replacing your windows you will save but it is difficult to provide an accurate saving due to so many variables but on average, you can save anywhere from £50 to £250 per year on your energy bills in the UK by upgrading to double glazing, depending on several factors like:

What affects how much you save?

  1. Type of property

    • Detached homes save the most — up to £250/year.

    • Semi-detached or mid-terrace homes tend to save around £120–£160/year.

    • Flats might save £50–£100/year.

  2. Window energy rating

    • A-rated double glazing (the most efficient) provides the highest savings.

    • Older or lower-rated windows won’t perform as well.

  3. Number and size of windows replaced

    • More windows = more potential savings, especially if replacing single glazing.

  4. Your current heating habits

    • If you heat your home regularly or keep the thermostat high, you’ll notice a bigger difference.

  5. Type of glazing you’re replacing

    • Replacing single-glazed windows offers the biggest benefit.

    • Replacing older double glazing with new, energy-efficient units still improves insulation but with more modest savings.

 Bonus: It’s not just about the bills

Double glazing also:

  • Makes your home more comfortable (warmer in winter, cooler in summer)

  • Cuts down on draughts and cold spots

  • Reduces outside noise

  • Can increase your property’s resale value