Secondary glazing is becoming an increasingly popular solution for homeowners across the UK who want to enjoy warmer, quieter living spaces—without having to replace their original windows, new research suggests.
This approach involves fitting a slim, internal pane alongside existing window frames. It offers a noticeable improvement in insulation and soundproofing—making it especially valuable for period homes and listed buildings where double glazing isn’t permitted.
“In the last couple of years, interest in secondary glazing has really taken off,” says Colin, founder of Colin’s Sash Windows, a company that supplies both secondary glazing and traditional timber sash windows nationwide.
“It’s discreet, it’s effective, and it’s often half the cost of full window replacements.”
According to industry sources (GGF / British Glass, 2023), around 80 million windows in the UK fail to meet current energy efficiency standards. One in ten properties still has single glazing, which can lead to up to 20% of household heat being lost through the glass (Energy Saving Trust).
In addition to retaining heat, secondary glazing can dramatically reduce noise—by as much as 80%, according to Colin’s Sash Windows. This has made it a popular choice for properties near busy roads, railway lines or airports, with some installations backed by local authority or airport grant schemes.
An estimated 3 million UK homes still rely on single-glazed windows, particularly in older or character buildings.
For landlords, the benefits are both practical and financial.
“We often hear from landlords who are losing tenants because flats are too cold or too noisy,” Colin said. “Secondary glazing is a cost-effective way to fix both problems, protect rental income, and improve the property’s EPC rating.”
With stricter energy regulations looming for rental properties, enhancing window insulation is fast becoming a priority. Secondary glazing offers an affordable way to increase EPC scores without major renovation work.
In London, demand is particularly high in conservation areas, where traditional window aesthetics must be preserved. Meanwhile, historic cities such as Bath, York and Edinburgh are seeing a steady increase in installations as owners seek practical, planning-friendly upgrades.
“Secondary glazing used to be niche, but now it’s becoming mainstream. People want warmer, quieter homes and this is a smart, affordable way to get there,” Colin added.
