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Windows and doors

Energy is lost through windows and doors from heat passing through the fabric, in particular the glass, as well as by warm air escaping through gaps in and around the frames.

Photograph illustrating the English Heritage web page on Saving Energy / Windows and Doors

© Core Sash Windows

Improving thermal performance

The thermal performance of both window and doors can be improved relatively easily without detracting from their appearance. Windows can be repaired and their mechanisms overhauled.

The benefits of simple repairs should not be underestimated. 

Simple window repairs

Freeing windows to open and shut properly is the best place to start with any window improvement.

Much of the heat lost through windows is actually through leaks and the resulting draughts are a disproportionately large source of discomfort. Providing old windows and doors with effective draught stripping therefore yields great benefits.

Read more about draught-stripping windows and doors:

  • Energy Efficiency and Historic Buildings: Draught-proofing windows and doors
    Energy Efficiency and Historic Buildings: Draught-proofing windows and doors
    Publication Date: 30 Mar 2012
    This guidance provides advice on the principles, risks, materials and methods for improving the thermal performance of existing windows and doors by draught-proofing.
    More info

Secondary glazing

Secondary glazing for windows can be more expensive than overhauling and draught-stripping so may not be cost effective on grounds of energy efficiency alone. However, secondary glazing does provide other benefits such as sound- proofing.

Read more about secondary glazing for windows:

  • Energy Efficiency and Historic Buildings: Secondary glazing for windows
    Energy Efficiency and Historic Buildings: Secondary glazing for windows
    Publication Date: 30 Mar 2012
    This guidance note provides advice on the principles, risks, materials and methods for upgrading the thermal performance of windows by the addition of secondary glazing.
    More info

Shutters and Curtains

The benefit of shutters and curtains is often forgotten.

Working shutters cannot match the performance of double glazing but they can make a big difference. Similarly heavy curtains will reduce heat loss.