Retrofitting creates trade-off between efficiency and heritage for buildings

Retrofitting properties with relevant green tech is essential for improving energy efficiency and decarbonising the property sector. Improving the efficiency of heritage properties creates a trade-off for architects and developers, but it’s possible to create energy efficient buildings while protecting their heritage.

What’s the trade-off?

Certain properties have legal rights which limit what developers are allowed to do with the building. For example, Conservation Officers are renowned for refusing permission for the installation of solar PV on heritage properties and properties in conservation areas, citing disruption of heritage, drastic alteration of building aesthetics, and loss of character as key reasons. This means individuals and businesses with heritage properties will face far more complex processes of green retrofitting.

This doesn’t mean that heritage properties cannot be retrofitted. Many heritage properties and ageing buildings need insulation and green tech solutions to limit heating loss and improve both quality and efficiency. Increasing the rollout of green building technology in conservation areas means setting a precedent for the presence of green tech in these areas. Conservation Officers are more likely to approve building retrofit projects one a precedent has been set.

Conservation and net zero goals

The UK has 33 world heritage sites, 374,300 listed buildings, and roughly 9,800 conservation areas. The Building Research Establishment also found that the UK’s building stock is the oldest in Europe, with 38 per cent of homes built before 1946.

With such a high proportion of UK buildings protected by heritage laws coupled with the UK’s reputation for having the poorest insulation in Europe, the government’s net zero 2050 target needs compromise for successful delivery. That compromise comes in the form of internal wall insulation.

If maintaining a building’s aesthetic is of paramount importance, then internal wall insulation is the most viable solution for improving energy efficiency while protecting character. However, internal wall insulation is more complicated and costly and, if not measured correctly, could damage the building. External wall insulation is a cheaper and more effective option, but planning rights to retrofit heritage properties with this type of insulation is hard to come by, particularly with windows and glazing which has a distinctly modern look which contradicts traditional heritage properties.

What the experts think

“We’ve had a few heritage projects where it was hard to identify where the healthy trade-off lies,” says Ralf Thiede, director of Daniels Thiede Architects Limited. “The best way to improve the energy efficiency is generally to aim for compact, simple design solutions, but the aesthetic and character of a building may demand a different approach. This can make it hard to deliver an efficient building economically while protecting its cultural heritage.” 

Ralf explains that there is no definitive blueprint when it comes to retrofitting heritage properties and listed buildings; a careful planning process is required.

“You have to take it on a building-by-building basis as each project provides unique challenges that are difficult to address with no general approach. You need to identify why a building is listed, understand what makes it a heritage asset, and how that impacts retrofit plans,” says Ralf. “Depending on the property, you may have to retain certain features which cannot be altered with green building technology. Reversibility is also key. If you do make alterations, consider whether these can be reversed in the future or if the changes are permanent.”

Overall, the market for retrofitting heritage and listed properties remains challenging and there is still a lot to learn about how we can achieve the best results. In the future, clearer guidelines combined with widely available exemplar case studies and associated performance data would support architects, retrofitters and developers in their quest to improve the energy efficiency of buildings across the UK while maintaining cultural integrity. However, perhaps we have to accept that a small number of properties have limited potential for the installation of energy efficiency technology.