Retrofit for Heritage Buildings

Essential tips

---

The UK’s building stock is responsible for a significant proportion of its total carbon emissions. Retrofitting buildings to enhance their efficiency and performance, and move away from systems reliant on fossil fuels, will be essential for the country to reach its target of net zero by 2050.

Listed (legally protected) historic buildings are part of this picture. It is a common misconception that listing prevents any alteration and is therefore a blocker to environmentally-friendly progress. But this is not always the case – there are many ways in which owners can enact positive changes to historic places. However, it is key to remember that listed buildings exist within a particular legal framework. Understanding how to gain the necessary permissions will help you deliver your project more seamlessly.

The retrofit process is rigorous and can be intimidating, but the Delivery Associates Network can help you through it with our network of Subject Matter Experts (SMEs).

1. Follow the legislation

The first thing to know is that it is against the law to carry out unauthorised works to your listed building. You will need to obtain listed building consent (LBC) from your local planning authority for any change that affects its character or appearance. Some activities that may seem like routine maintenance could also require consent, so it is always best to check with your local conservation officer.

The listing grade or category of the building (I, II* or II in England and Wales; A, B or C in Scotland; A, B+, B1 or B2 in Northern Ireland) is an indication of the level of scrutiny involved in assessing an LBC application. Other types of designation, including conservation areas, can also have a bearing. Depending on the listing grade, you may also need to speak to your national heritage organisation (Historic England, Historic Environment Scotland, Cadw or the Historic Environment Division in Northern Ireland) and other groups, known as national amenity societies, which have a powerful voice concerning buildings from certain historical periods.

LBC applications must be offered for public consultation. Taking some time to address any potential objections before you submit your application can substantially de-risk the process. The Delivery Associates Network’s SMEs can offer more tailored support if you are preparing for your public consultation.

2. Take your time to understand the building

In assessing your proposals, your colleagues at the local planning authority will consider how well you understand the building the proposals will affect. At the top of your local planning authority’s list will be two closely interconnected considerations: the building’s condition and performance (essentially how well the building works), and its heritage significance (why it is important).

How well does your building work?

Retrofit solutions should work with the fabric of the building, not against it: it is rarely effective to fundamentally change how an existing building reacts to heat, cold, fresh air, rainwater, humidity, and other factors.

Architects and builders throughout history have developed responses to these environmental factors, many of which may still be valid. Some may have been compromised over time, potentially by well-meaning attempts to modernise fabric and systems. There are countless examples of ‘upgraded’ materials creating more problems in historic buildings, as owners attempted to correct perceived flaws which never needed fixing in the first place.

It will be important to assess these aspects in detail, ideally with careful monitoring and survey information. Your upgrade scheme will be far better if you know how the building works (or doesn’t work!) today.

Why is it so important?

Your colleagues at the local planning authority will expect you to demonstrate that you understand why your building is listed, and which bits of it are more or less important from a heritage perspective. With this information you can assess the impact of your proposals – and then make a case justifying that impact.

In heritage terms this importance is known as significance. It is a summation of different values or interests – generally covering aesthetics, archaeological evidence, historical meaning and a sense of how the place resonates with different groups of people. Significance can be applied to a building overall (in the context of streetscapes, areas and broader categories of buildings) and to constituent elements within a building, since not every part will have the same significance as the whole.

If your proposed changes apply to elements of lower significance they will generally have less of an impact on the overall character of the building, and are therefore more likely to gain consent. Many buildings have parts that detract from their overall significance, so altering or removing these parts might help to mitigate more contentious changes elsewhere.

3. Be creative: opportunities exist

There is a growing acceptance that even listed buildings must be adapted to contribute to reductions in our collective carbon footprint. Many of the stakeholder organisations you may speak to might have already made their own net-zero commitments, and this will have a bearing on their responses to your retrofit proposals.

Keeping a building sustainably in use is one of the best ways of conserving it. From this perspective, one way to mitigate any impacts of your proposed changes can to balance those against its future use and viability.

A really good example of this is Arup’s work at the University of Leicester’s Engineering Building, listed at Grade II*, where we changed the entire glass skin of the lower block in order to improve its energy efficiency and occupant comfort. This was a major change, which required very careful design and stakeholder consultation, but crucially allowed the Engineering department to continue using its original, purpose-made building.

Many contemporary solutions can be hugely beneficial to your historic buildings, where the best of the new can be applied to the best of the old. Clean sources of power and heat can generally be integrated in sensitive ways; draughts can be stopped and ventilation provided by other means; weak points in a building’s thermal envelope can be carefully insulated.

Even a building as important as Lambeth Palace in London (Grade I), ancient home of the Archbishop of Canterbury, can be upgraded. Here Arup designed a suite of retrofit solutions, including new air-source heat pumps, solar panels and induction kitchen equipment, to fully decarbonise the building.

A creative approach to design and conservation, underpinned by a thorough understanding of the historic fabric in question, can transform old spaces and make them more resilient, more comfortable, and fit for the future.

The Delivery Associates Network is here to help you navigate this process confidently and to provide the best advice on how to make the most out of your heritage building retrofit project.  

Thomas leads Arup’s Heritage & Conservation Architecture team. He has delivered design and conservation projects for some of the country’s finest historic buildings, and holds heritage advisory roles for a number of high-profile institutions.

If you have any questions, or would like support, please contact your Delivery Associate, or email DeliveryAssociatesNetwork@Arup.com