Timber window retrofit solutions and preservation

There are many complexities surrounding the retrofitting of energy efficiency measures in historic homes, with the main challenge focused on the balancing act of the preservation of cultural assets with the imperative to achieve net zero targets.

Coupled with a lack of training and knowledge, this has been a contentious issue which has faced the sector, with many opting for new construction as a seemingly more straightforward option.

When focusing on windows in particular, retrofitting energy-saving measures to existing timber windows can prevent waste and avoid the increase in carbon emissions created in the manufacture of new replacement windows.

Why timber?

Timber windows have long been used in historic buildings, with timber remaining highly prized for its natural beauty and environmental credentials as a low-carbon material. Not only do they look beautiful, but they are sustainable and offer exceptional long-term value.

When it comes to the upgrade or replacement of original timber joinery in a listed property, choosing the right timber is important in ensuring that it is replaced ‘like-for-like’ when possible, and performs as intended.

So, what are the benefits of restoration projects?

The benefits of restoration projects

First of all, retrofitting over new construction poses huge environmental benefits.

According to the report, Embodied Carbon: Three reasons we should care, available from the Open University website, making energy efficiency improvements to existing buildings is at least 4% more beneficial in lifecycle carbon terms than demolishing and replacing. The report also highlighted that maintenance, periodic renewal and conservation-focused refurbishment have the potential to save between 30 and 50% of carbon emissions while saving up to 40% in energy consumption.

Given the several benefits, what are the key areas affecting the retrofit of timber windows in historic homes?

• The planning system

Where planning permission is required, the local planning authority is subject to special heritage legal duties which require them to consider the desirability of preserving the listed building or conservation area. As a result, it is important to understand how legal duties underpin heritage planning policies in the National Planning Policy Framework, which emphasises the importance of identifying the heritage impacts. Along with this, the framework sets out the tests which are to be applied by local planning authorities in determining applications with impacts on heritage assets.

• Local authority skills, training and capacity

Not all local planning authorities have a dedicated conservation officer. Those who do not, often share a post with neighbouring councils or seek heritage advice from consultants.

• Guidance and information

Historic England’s 2022 Survey of Listed Building Owners and Occupiers found that over half (54%) of owners and occupiers think it is difficult to find reliable guidance about how to retrofit listed homes. The range of information sources on retrofitting which owners turn to is broad, and includes information from local councils (16%), architects (14%), builders (13%), professional organisations (9%), Historic England (8%), UK Government sources (7%), and local heritage organisations (4%).

• Construction industry skills, training and capacity

The loss of skills in the heritage construction industry is a key barrier to adapting historic homes. This view is supported by the Construction Industry Training Board (CITB) Construction Skills Network Industry Outlook 2023-27 which suggests there are two main factors: the skills gap and workforce shortages.

• Affordability and financial incentives

Historic England’s 2022 survey of owners and occupiers of listed buildings found that cost was a common barrier to retrofitting energy-saving measures to their property more so than lack of knowledge, difficulty finding a contractor, the disruption of works, or concerns around damaging the character of the home.

How the BWF can support

In response to these challenges, the BWF provides support through its Woodworking Industry Training Forum (WITForum). Recognising the shortage of training and resources, WITForum collaborates with BWF members to address skill gaps in the woodworking and joinery manufacturing sector. Moreover, the BWF continues to develop guidance in partnership with its members to address concerns related to timber windows in historic homes, facilitated through our heritage and focus group initiatives.