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How Windows Affect Your EPC Rating in Scotland

8 min read
5 January 2026
Scottish Energy Efficiency

Quick Answer

Windows can impact your EPC by 5-15 points. Upgrading from single to double glazing typically improves EPC by one band (e.g., E to D). From old double to A-rated units provides smaller but meaningful improvement. Window efficiency is assessed separately from other building elements.

Understanding how glazing improvements affect your Energy Performance Certificate and property value.

In This Article

  • Key facts and figures
  • Real Scottish examples
  • Common questions answered
  • Next steps and resources

Frequently Asked Questions

Single to double: 5-15 points. Old double to new A-rated: 3-8 points. Impact depends on window area and current rating.

Yes. They assess glazing type, frame material, and estimated age. Certificates identify windows needing improvement.

Not usually. Loft insulation and heating controls often provide better EPC improvement per pound spent.

Potentially. Minimum EPC requirements are tightening. Properties with poor glazing may need upgrades to remain lettable.

Secondary glazing is recognised by EPC assessments. Window films typically aren't formally recognised but improve actual performance.

Part of our Windows & Thermal Efficiency guide

Understanding heat loss, glazing options, and thermal improvements for Scottish homes

Visit Windows & Thermal Efficiency Scotland
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