LANDLORD KNOWLEDGE
Windows, glazing and EPC improvement
Upgrading glazing can affect the assessed building, but replacing serviceable windows may be a costly way to close a small EPC gap.
When is it worth investigating?
Single glazing, draughts, frame condition and the proportion of glazing are relevant. Heritage or leasehold restrictions may change the available options.
When might it be the wrong first step?
Compare glazing with suitable insulation and controls. Replacement must account for ventilation and building requirements; blocking background ventilation can create problems.
How many EPC points could it add?
There is no universal points award. The current property, existing measures, installation specification and assessment methodology all matter. Use the recorded recommendation sequence or an assessor-reviewed scenario; do not add independent estimates together as a guaranteed result.
How much should you allow?
See the published cost benchmarks and request a quotation for the actual scope. The price of a measure is different from the cost of achieving a target rating.
What should happen first?
Document existing glazing, frame types and proposed product performance. Include making good, ventilation and any permissions in the quote.
Further reading: Energy Saving Trust. Guidance checked 4 October 2026. Installation suitability needs a property assessment.