How to Add Double Glazed Windows to Listed Buildings

• 22 April 2025|
• News

Upgrading the thermal performance of listed buildings, while worthwhile, can prove to be a challenging project.

For those working on heritage properties, the balance between preservation and modernisation requires expert knowledge and careful consideration. Finding the right double glazed windows for listed buildings means finding those that can respect historical aesthetics while delivering modern performance benefits.

At Lomax + Wood, we have over 30 years of experience in working with listed buildings and in conservation areas, providing replacement timber windows that marry sympathetic design with upgraded performance. Whether you’re an architect, an installer or a property owner, we have the expertise needed to assist with any heritage project.

Are double glazed windows suitable for listed buildings?

Yes, double glazed windows can be suitable for listed buildings if they are installed in a sympathetic way that preserves the historic character of the property. It’s important to consult with conservation officers and adhere to any regulations to ensure the windows meet the requirements for listed buildings.

The challenges of working with listed buildings

Listed buildings in the UK are protected by law due to their historical or architectural significance. Any alterations, including window replacement, require listed building consent from local planning authorities.

This regulatory framework exists to preserve the character and special interest of these heritage buildings. For architects and trade professional, the addition of double glazing in historic properties creates a unique set of challenges, including:

• The need to improve energy performance without compromising heritage value
• Stringent approval processes with conservation officers who must approve any changes
• The requirement to maintain authentic appearances that align with the original design
• Technical constraints of working with existing apertures and structural elements that weren’t designed for modern double glazing

These challenges often lead to extended planning phases and require specialised expertise in heritage window manufacturing – areas where partnering with experienced timber window specialists (like Lomax + Wood) becomes invaluable.

Heritage double glazed windows from Lomax + Wood: authenticity & sustainability

Despite these challenges, there are approved pathways for introducing double glazed windows to listed buildings. It’s important to find windows that will accurately reflect the design of the original windows.

At Lomax + Wood, we specialise in creating bespoke timber windows that satisfy the demands of conservation authorities while delivering modern performance benefits.

We are proud to hold both FSC® and PEFC Chain of Custody certifications, ensuring that all timber we use is sourced from responsibly managed forests. Unlike other timber manufacturers, we hold full Chain of Custody certifications – this gives the timber we use in our windows and doors full traceability from forest to finished product.

Double glazed sash windows

Lomax + Wood’s double glazed timber sash windows combine centuries-old craftsmanship with cutting-edge performance standards.

Our box sash windows maintain the cherished aesthetic of traditional designs—complete with authentic proportioning, detailed mouldings, and classic hardware—while delivering remarkable thermal efficiency with U-values as low as 1.1 W/m²K.

The traditional weight and pulley mechanism ensures smooth, balanced operation that remains faithful to historical designs.

For projects where cost considerations are paramount, our spring-balanced sash windows provide a more economical solution without sacrificing visual authenticity, making them particularly valuable for developers working in conservation-sensitive environments. Both window systems incorporate advanced glazing technology, featuring low-emissivity coatings, argon-filled cavities, and warm edge spacer bars that dramatically improve thermal retention.

The precision-engineered timber frames of our sash windows include comprehensive weather-sealing that eliminates the common problems of condensation and draughts.

These windows demonstrate our commitment to protecting architectural heritage while addressing contemporary demands for energy efficiency, security, and long-term durability, providing architects with confident solutions for even the most demanding historical renovations.

Double glazed flush casement windows

For properties where casement windows are the appropriate choice, our flush casement windows deliver the perfect blend of heritage style and modern performance.

Our casement windows provide U-values of 1.2 W/m²K as standard, with upgrade options available to achieve values as low as 1.0 W/m²K. Additionally, our casement windows are suitable for projects within bustling urban areas, as our Acoustic + range can achieve noise reduction up to 42dB.

These windows are fully customisable with a range of ironmongery and various timber options, including Engineered Redwood, Hardwood, Oak, and Accoya – each selected for its durability and beauty.

Vacuum glazing solutions for single glazed requirements

Although we’d always recommend double glazing to ensure thermal efficiency, there may be some situations where only single glazing will be accepted. In this instance, we can provide a single-glazed sliding sash windows with innovative vacuum sealed units.

Our vacuum glazing features an ultra-thin profile that fits into traditional single glazed frames, preserving original proportions and sight lines while still minimising heat loss. Despite their minimal thickness, these units provide improved thermal performance that approaches standard double glazing efficiency.

The authentic appearance of vacuum glazing satisfies even the most demanding conservation requirements for visual authenticity. Homeowners benefit from significant improvements in energy efficiency compared to traditional single glazing, reducing heating costs while preserving the character of historic buildings.

Balancing preservation with performance

Double glazed windows for listed buildings represent a specialised area requiring expert knowledge and craftsmanship. By working with timber window specialists who understand both conservation requirements and modern performance standards, architects and developers can successfully navigate the complexities of heritage renovations while delivering projects that maintain historical authenticity.

Double glazed windows for listed buildings: contact Lomax + Wood today

If you’re an architect, developer, or homeowner working with a listed property, Lomax + Wood can provide the expertise needed to achieve planning consent while improving energy efficiency and comfort. Our team understands the nuances of heritage window design and can guide you through the entire process.

We also have several showrooms which showcase just some of the windows styles we offer. If you would like to take the first step and discuss your requirements, please get in touch to book a showroom appointment.

To discuss your specific requirements or to receive a no-obligation quotation, please complete our online contact form or call 01277 353857.