How Quickslide’s Legacy VS sash windows are bringing new levels of energy efficiency to period properties and listed buildings.  

When it comes to window replacements, energy efficiency is a key driver for buyers. Especially in older and period properties, where solid wall construction means there is a limit to how much can be done to reduce heat loss through, for example, adding cavity wall insulation.

It’s estimated that a quarter of British homes have solid walls, with most of these built before 1920 with traditional window designs. For many of these, such as listed buildings or those in heritage and conservation areas, authentically replicating traditional sash windows isn’t just an aesthetic preference, it’s essential to having building consent granted.

Quickslide’s Legacy VS is billed as ‘the gold standard’ for heritage windows, and it now comes with the option of a 1.2 U-value too, a superior level of thermal insulation that is the target for windows going into new-build properties. It makes the window extremely effective at preventing heat loss and means heritage, listed and conservation property owners can now enjoy the same level of comfort and performance in their sash windows as their new-build counterparts.

“Regulations are becoming stricter, with more stringent requirements for energy efficiency,” says Quickslide’s managing director, Ben Weber. “In new build homes, the target U-value for windows is set at 1.2 W/m²K, with the limiting U-value for windows at 1.6 W/m²K. Our sash windows can hit the target, rather than settling for the limiting U-value, making it easier for builders and homeowners to comply with the law and adding real value to properties by increasing their energy efficiency.”

Quickslide has achieved this level of thermal efficiency by inserting additional insulating materials into some of the chambers in the frame and cill and upgrading the coating on the glass unit. “What we’ve not done is add expensive krypton gas or triple glazing which would compromise the acceptable depth of a traditional sash reveal,” says Ben.

This last point is important, because in addition to improving Legacy VS’s energy efficiency, Quickslide has also meticulously enhanced Legacy’s detailed heritage styling and authenticity. There’s a new slim mid rail that, at over a centimetre narrower than the standard option, is equivalent to those of traditional timber sashes.

Coupled with 90° mechanical joints and refined sash horns which run as a continuous part of the top sash and remove the tell-tale ‘lip’ of the sash horn end cap, Legacy VS is a closer match than ever to a timber sash.

“With details like the slim mid rail, mechanical joints and a choice of nine woodgrain finishes from stock in addition to bespoke colours, it’s harder than ever to tell the difference between Legacy VS and timber by eye,” says Ben. “And planning authorities agree: our new Legacy VS means many more listed and conservation properties can now pass planning consent with modern, efficient heritage windows.

“Up to now, homeowners in conservation areas have faced a very limited choice when it comes to replacement windows, often having to compromise energy performance in order to get planning approval with like-for-like timber windows instead.

“Legacy VS means homeowners now have a genuine choice for affordable, low-maintenance traditional sash windows, with the highest levels of energy efficiency to boot.”