Historic England’s chair Lord Mendoza’s comments on the role the heritage sector has to play in addressing housing and environmental needs have placed a renewed focus on retrofit’s role in reducing the sector’s carbon emissions. Emma Wells believes that this is a step in the right direction
As we look at the ambitious carbon reduction targets that we see across the construction industry, it’s no surprise that retrofitting historic fabric is increasingly being preferred to the construction of new buildings where possible.
With the amount of embedded carbon emitted in the construction process, it stands to reason that the greenest building is the one that has already been built, and the recent comments from Lord Mendoza are a breath of fresh air in that respect.
There is a perceived stigma surrounding retrofitting heritage buildings. Still, the reality is that taking this approach is hugely beneficial when it comes to cutting down on carbon emissions and – consequently – the race to net zero.
The challenge lies in retrofitting in a manner that is sensitive to a building’s history and the devil is in the detail given the complexities of historic fabric. Careful retrofitting of historic fabric can lead to substantial carbon savings – if you take an average home built in the Victorian era, for example, you can quite comfortably achieve carbon savings of 85% or above.
It is important that we don’t fall into the trap of thinking that one-size-fits-all. While we have seen this work for new buildings with concepts and standards such as Passivhaus and BREEAM, the reality is that this kind of approach would be difficult to implement for historic buildings given the intricacies and nuances of each individual building.
However, there is a fine balance that needs to be struck between tailoring the process on a case-by-case basis, and the need for better consistency across the industry.
Lord Mendoza’s comments alluded to the fact that while there is a lot of cross-industry guidance from the likes of Historic England and local authorities, there isn’t any overarching statute or policy guiding it all, so a unified approach is hard to define.
This is where it is vital to have the right people involved when it comes to retrofitting in this sector, as it can only be done to the best possible standard by understanding the fabric of the building and the complexities that presents.
The devil is in the detail given the complexities of historic fabric
Another key tenet of Lord Mendoza’s recent comments was the role that historic buildings play in helping solve the housing crisis. We are a nation of historic buildings, and this housing stock should be valued rather than being seen as costly millstones around the neck of owners.
Much of this derives from a misunderstanding of how the building fabric works, and it is incumbent on the heritage sector to do a better job of championing the benefits of older homes and finding ways to make them more effective, efficient and sustainable. Part of this requires education and helping those who own the existing building stock to identify ways they can make changes that are seemingly small but can have big positive impacts.
It’s not a matter of whether the built fabric can or can’t be retrofitted but more so how it’s done. All historic fabric is different as it’s a unique composition of materials, alterations, and amendments. Analysing each building is key to knowing what materials they comprise, how they’re heated and so on, so we can find the right retrofitting solutions.
The knowledge gap is understandable – it isn’t like you are presented with a manual from Historic England when you buy a listed building – but the misconceptions of what you can and can’t do with the fabric can easily be remedied through having the right conversations with the right people.
Doing this also alleviates the concerns around cost, which is arguably the biggest barrier to retrofitting historic housing stock. Having those conversations early in the process creates a greater understanding of the balance between cost and output and where the sweet spot between the two lies.
Of course, listed buildings involve a more complex permission process as the majority of retrofitting measures require listed building consent, but the fact that listed buildings can apply for EPC exemption means that they can be easier to deal with. Furthermore, some local authorities, such as the Royal Borough of Kensington and Chelsea, have introduced new consent orders providing consent for solar panels and double glazing on most Grade II and II* listed buildings without the need for individual listed building consent.
Retrofitting historic buildings will always be something that needs to be looked at on a case-by-case basis as every project will have its own story to tell and issues to address. However, by engaging with those with relevant expertise, even the greatest of challenges can be turned into opportunities.
Dr Emma Wells is the technical director for historic buildings at SLR Consulting