Achieving a better energy rating with your sash windows is high on the list for both homeowners and developers. That’s why our hardwood timber windows are engineered to improve sash window energy rating without affecting their traditional design.
In South West London, energy performance is becoming a bigger factor in property valuation and resale. Older properties in Wimbledon, Clapham and Battersea often lose significant heat through outdated or single-glazed sash windows. Upgrading to modern timber alternatives allows you to maintain external character while improving thermal comfort.
We offer double-glazed units with warm edge spacers, low-E coatings and advanced seals—all tested to deliver U-values that meet or exceed Part L of Building Regulations. On one Streatham property, these upgrades helped the owners lift their EPC rating from E to C—enough to satisfy remortgage criteria and attract buyers seeking energy-efficient homes.
The best part?
None of the external sightlines were changed. We used slimline glazing and matched sash profiles so that the conservation officer approved the work with no objections.
For landlords and developers, improving window energy performance helps meet minimum efficiency standards for rentals and reduces tenant complaints related to draughts or condensation. On larger schemes, the improvement in EPC across the building can directly affect rental yield and valuation.
Our team can model expected U-values based on your glazing and frame specification, helping you build a case for planning or demonstrate compliance to mortgage or lettings agents. Better still, we do it without introducing plastic or aluminium to the building envelope.
If you’re upgrading windows as part of a larger renovation, now is the time to ensure the sash units are helping rather than hurting your energy rating. Our hardwood timber windows help bridge the gap between heritage and efficiency.