Improving Energy Efficiency in Listed Buildings: Balancing Heritage and Sustainability

As the UK works towards its target of net zero by 2050, improving the energy efficiency of existing buildings is becoming increasingly important. However, for owners of historic, heritage and listed properties, making these improvements can be complex.

These buildings hold significant architectural and historic value, often protected by planning regulations that restrict alterations to original features. With 379,458 listed buildings in England alone, according to Historic England, finding practical ways to improve their energy performance is an important part of the UK’s wider sustainability ambitions.

The challenge is to reduce heat loss, improve comfort and lower energy consumption without compromising the character and integrity of these properties. Achieving this requires a considered approach that combines traditional materials and craftsmanship with modern technology.

Why Is Retrofitting Listed Buildings So Important?

Historic properties were generally built long before modern energy efficiency standards existed. Traditional construction methods, single-glazed windows and limited insulation can all contribute to heat loss, making some properties more expensive to heat and less comfortable to live in.

Retrofitting offers an opportunity to address these issues while preserving the features that make historic buildings distinctive. Measures such as improving draught-proofing, upgrading glazing and enhancing insulation can help reduce energy consumption and improve indoor comfort.

However, retrofitting a listed building is not the same as upgrading a modern property. Original windows, doors, masonry and other architectural details may be protected, meaning that standard replacement solutions are not always appropriate.

The priority should be to understand the building’s existing condition and identify improvements that are suitable for its construction, significance and planning requirements.

Improving Window Performance Without Losing Original Features

Windows are an important consideration when improving the energy efficiency of a heritage property. Original timber sash and casement windows contribute to a building’s architectural character, but age-related wear, gaps and ineffective seals can allow draughts and heat to escape.

Replacing these windows is not always necessary. In many cases, restoration and targeted upgrades can improve performance while retaining the original timber, glazing bars and sightlines.

Draught-proofing with the Ventrolla Perimeter Sealing System

At Ventrolla, our restoration-first approach focuses on retaining and improving existing timber windows wherever possible.

The Ventrolla Perimeter Sealing System (VPSS) is designed to improve the thermal and acoustic performance of traditional sash windows. By creating a discreet seal around the moving sashes, the system helps reduce draughts and heat loss while improving sound insulation.

The VPSS can improve Window Energy Ratings by up to 30%, helping homeowners enhance window performance without automatically resorting to complete replacement.

This approach allows original windows to remain an integral part of the building, preserving their historic character while making them better suited to modern living.

Making Window Maintenance Easier with the Sash Removal System

Ongoing maintenance is another important consideration for historic timber windows. Accessing the box frame can be difficult, particularly when working with traditional sash windows.

The Ventrolla Sash Removal System (SRS) provides a discreet solution. Integrated into the sides of the sashes, the system allows the upper and lower sashes to be removed safely, providing access to the window box frame for maintenance and repairs.

As the system is concealed from view internally and externally, it helps protect the appearance of the original window while supporting easier maintenance over time.

Together, these technologies demonstrate how carefully designed interventions can improve the performance and practicality of traditional windows without unnecessarily altering their appearance.

When Is Replacement the Right Option?

Although restoration should be considered first, some windows may be too deteriorated to repair effectively. In these circumstances, bespoke replacement can offer a suitable alternative, provided the design and materials are appropriate for the building.

New timber sash and casement windows can be manufactured to reflect the original proportions, profiles and detailing, helping maintain the architectural character of the property.

At Ventrolla, replacement windows are made to suit each customer’s requirements, combining traditional joinery with modern frame and glazing technology. The VPSS can also be incorporated to help improve draught reduction and overall window performance.

New windows are tested against relevant standards, with Ventrolla’s manufacturing processes incorporating FENSA and British Standards Institute (BSI) requirements.

For listed buildings, it is essential to establish whether replacement is acceptable before proceeding. Listed building consent may be required, and homeowners should seek appropriate advice before making changes to original windows or glazing.

Looking Beyond Windows: Other Ways to Improve Energy Efficiency

While windows can make a meaningful contribution to a property’s energy performance, they are only one part of the wider retrofit picture.

A whole-building approach considers how different elements work together, helping homeowners prioritise improvements that are appropriate for the property’s construction and condition.

Potential measures include:

• Improving insulation: Carefully specified insulation to walls, roofs and floors can reduce heat loss, although the suitability of each measure depends on the building’s construction and moisture behaviour.
• Upgrading roof materials: Where repairs or replacement are necessary, traditional or reclaimed materials, such as slate or clay tiles, may help preserve the building’s appearance.
• Reducing draughts: Identifying gaps around windows, doors and other openings can help improve comfort and reduce unwanted air movement.
• Reviewing glazing options: Secondary glazing or specialist glazing solutions may offer opportunities to improve thermal performance, subject to the property’s significance and any relevant consent requirements.
• Maintaining existing materials: Repairing original building elements and addressing defects can help protect the building fabric while supporting its long-term performance.

Not every measure will be suitable for every property. Traditional buildings need to be assessed individually to ensure that improvements do not introduce problems such as trapped moisture, condensation or damage to historic materials.

Using specialists with experience in heritage buildings can help homeowners understand the available options and develop a practical plan for improvement.

The Challenge of Planning Regulations and Heritage Protection

One of the main barriers to improving the energy performance of listed buildings is navigating the planning process.

Historic features may be protected because of their architectural or cultural significance, meaning that measures commonly used in modern buildings, including certain types of double glazing, insulation or renewable energy installations, may not be acceptable in every case.

The Parliamentary Office of Science and Technology has highlighted the need to retrofit the UK’s historic building stock as part of the transition to net zero. However, achieving this requires a balance between improving energy performance and protecting the significance of historic buildings.

Planning decisions can also vary according to the building, its location and the significance of the features affected. This can make it difficult for homeowners to understand which improvements are likely to be acceptable before investing in surveys, designs and applications.

Greater consistency in guidance and decision-making could help property owners and heritage specialists identify appropriate solutions more efficiently. Clearer guidance would also support earlier conversations between homeowners, conservation officers and contractors, reducing the risk of unsuitable proposals and avoidable delays.

However, consistency should not mean applying the same solution to every building. A proportionate approach must recognise the differences between historic properties and allow decisions to reflect their individual significance and construction.

The Long-Term Benefits of Retrofitting Heritage Properties

Improving energy efficiency can offer several benefits for owners of historic and listed buildings.

Reducing draughts and heat loss can make rooms more comfortable throughout the year, while appropriate insulation and glazing upgrades may help lower energy consumption and running costs.

Carefully planned maintenance and restoration can also extend the useful life of original building features, reducing the need for more extensive interventions in the future.

Energy performance is an increasingly visible consideration for homeowners and prospective buyers. Although an improved Energy Performance Certificate (EPC) rating does not guarantee a higher property value, better energy performance and lower running costs may make a property more attractive to some buyers.

The financial case for retrofitting should nevertheless be considered alongside the costs of surveys, specialist materials, installation and any necessary consent. The most effective approach is to prioritise improvements that offer meaningful benefits while remaining appropriate for the building.

Preserving the Past While Preparing for the Future

Improving the energy efficiency of the UK’s historic building stock is an important part of the transition towards net zero. Yet these improvements must be achieved without losing the architectural details, traditional materials and historic features that make these buildings valuable.

A restoration-first approach, supported by sympathetic materials, specialist knowledge and carefully selected technology, can help homeowners improve comfort and performance while retaining original building fabric wherever possible.

At Ventrolla, we believe that preserving historic windows and improving their performance should go hand in hand. Through traditional restoration, bespoke replacement where necessary and discreet technologies such as the VPSS and SRS, we help homeowners find practical ways to care for their windows without compromising the character of their property.

With informed planning, appropriate expertise and a more consistent understanding of heritage retrofit, it is possible to protect the UK’s architectural heritage while making historic buildings more comfortable, efficient and sustainable for future generations.

References

1. Historic England (2024), figures relating to listed buildings in England.
2. Parliamentary Office of Science and Technology, Net Zero and the UK Historic Building Stock.