Heritage shouldn’t cost the Earth

This article was featured in Glass Times magazine’s April issue.


Roseview director Mike Bygrave discusses the challenge of creating authentic heritage windows that meet modern performance requirements, and how Roseview has overcome this to help their customers succeed.


Heritage windows are a well-established part of the glazing industry, spanning most product types and materials. Driven by consumer demand, the last three years have seen heritage windows become one of the industry’s most buoyant and profitable sectors.

“Homeowners are actively looking for authentic heritage-based windows. Nothing encapsulates heritage better than sash windows.” says Roseview director Mike Bygrave. “But, crucially, homeowners aren’t willing to sacrifice energy efficiency in favour of traditional windows.”

Heritage credentials

Roseview is well-known for pioneering timber-alternative sash windows. The company has won numerous awards and has forged a reputation for continually advancing the development of sash windows and the wider heritage window market.

“When it comes to heritage, especially in sash windows, we have a lot of experience.” Mike continues. “We’ve spent almost 40 years specialising in sash windows and focusing on improving them to the point where they’re essentially indistinguishable from timber.

“What we’ve learned over that time is that manufacturing a true heritage window isn’t just down to the authentic features and details you include. What’s really important is the way those details combine into a coherent whole. That’s why we develop things ourselves rather than relying on others. We can design details with the whole window in mind, so that everything works in harmony. That’s what homeowners see when they’re comparing products. They don’t focus on specific details in isolation, they want everything to work together: slim profiles throughout, putty lines, heritage astragal bars, traditional sash horns, seamless construction—the complete package.”

Energy efficiency

While Roseview have mastered traditional sash window aesthetics, Mike argues that window performance is equally important, and increasingly high on homeowners’ priority list. “Performance has always been important, but energy efficiency in particular has become a critical factor in homeowners’ decision-making.”

This is supported by wider analysis of the home improvements market. House prices dropped by 1.8% in 2023 (Nationwide HPI), which usually signals reduced spending on home improvements. However spending on energy efficiency products has increased. Over a six-month period in 2023 B&Q saw an 11% increase in homeowner spending on insulation materials, compared to 1.7% across the rest of their business. Meanwhile the NatWest Greener Homes Attitude Tracker found that 66% of homeowners are planning upgrades to the sustainability of their homes.

“Global events, rising energy costs and the high cost of living have combined to put energy efficiency at the forefront of consumers minds.” Mike says. “That can be problematic for heritage windows, which struggle to match the levels of more modern styles. Sash windows are the perfect example; they can’t have compression gaskets, triple glazing is unsuitable because of the weight and the way it interferes with astragal bars, and vacuum glazing is both expensive and limited.”

In partnership with REHAU, Roseview has overcome this with ThermoVFlex. ThermoVFlex is patented technology that reduces the u-value of Roseview’s Ultimate and Heritage Rose sash windows from 1.4 to 1.2 W/m2k, without requiring specialist glazing.

“ThermoVFlex is proof that developing sash windows isn’t just about the aesthetics.” says Mike. “It’s a profile enhancement that you can’t see on the finished window, but it brings the u-value down to a competitive modern level. It’s perfect for homeowners who want genuine sash window style but are equally concerned with energy efficiency.”

low u values with ThermoVFlex


More than a sum of its parts

“In a challenging market installers need a sash window supplier that helps them meet the needs of the modern homeowner.” Mike continues. “Window design and performance are crucial, but these need to be backed up by a fitter-friendly attitude. That includes a brand that homeowners recognise, strong marketing support and a dedication to quality, service and speed and the technology required to enable them. Combined, these make a compelling proposition for homeowners and installers alike.”