Funding information checked: September 2026. Funding terms can change; verify the current scheme before ordering work.
Secondary glazing is often considered for traditional sash and case windows because it can improve comfort while leaving the external window largely unchanged. For owners researching grants, however, it is important to distinguish between grant funding and loan funding.
Does Home Energy Scotland fund secondary glazing?
Yes, but under the current Home Energy Scotland Grant and Loan scheme, double glazing, triple glazing and secondary glazing are listed with up to £8,000 of loan funding and no grant funding for the glazing measure itself. The scheme states that this is for improving single glazing, not replacing existing double, triple or secondary glazing.
Where double or triple glazing is recommended but an applicant can only afford secondary glazing, the current terms say secondary glazing may be accepted with an explanatory cover letter, subject to the scheme’s application requirements.
Why secondary glazing suits many traditional windows
Historic Environment Scotland identifies secondary glazing as one of the most effective ways to reduce heat loss through sash windows while keeping the original external fabric. Its published guidance says secondary glazing can reduce heat loss by 63%, and that combining measures such as shutters or blinds can improve performance further.
Secondary glazing may also reduce outside noise and draughts. It is not automatically suitable for every property: ventilation, condensation risk, reveal depth, shutters, ironmongery and listed-building requirements all need consideration.
Secondary glazing in listed buildings
Because secondary glazing is fitted internally, it can sometimes offer a less visually intrusive route to improvement than replacing historic windows. That does not mean consent is never required. Owners of listed properties should confirm requirements with the relevant planning authority before altering significant historic fabric.
Repair and draught proof before or alongside glazing
A second layer of glazing does not cure rotten timber, failed putty, broken cords or badly fitting sashes. A fabric-first approach means dealing with defects and air leakage appropriately. See our window repair service and draught-proofing service.
Frequently asked questions
Is the £8,000 Home Energy Scotland glazing funding a grant?
No. The current published table lists up to £8,000 as loan funding for qualifying double, triple or secondary glazing and says grant funding is not available for glazing.
Can secondary glazing be fitted behind shutters?
Sometimes, but the design needs to account for shutter operation, window access, ventilation and available reveal depth. A site assessment is preferable to assuming a standard system will fit.
Will secondary glazing change the outside appearance?
It is installed internally, so external visual change can be limited. Sightlines and reflections still need thoughtful design, particularly in sensitive historic interiors.
Can secondary glazing eliminate condensation?
No system can guarantee that. Condensation depends on internal humidity, ventilation, surface temperatures and installation details. Those factors should be considered as part of the design.
Official scheme: Home Energy Scotland Grant and Loan.