The importance of retrofitting to tackle net zero

It’s a well-known fact that 80% of today’s buildings will still be in use by 2050 – the deadline for the UK government’s net zero targets – so why is the energy efficiency of our existing building stock not given as much airtime as new projects? Hannah Kissick, associate and our innovation team lead, explains the importance of retrofitting to tackle net zero. 

Much time, effort and resource has been put into constructing new low-energy buildings, with multiple organisations and accreditations – from Passivhaus, LETI, the RIBA 2030 Challenge and more – offering guidance and targets on reaching net zero.  

However, we cannot ignore the existing building stock on our route to net zero. These buildings are essential assets, especially for the public sector and local authorities with large, sometimes historic estates, that can be the most intensive to operate and are now required to meet targets they were never intended to achieve. We must reduce their carbon footprint if we are going to have an impact.  

Therefore, addressing the carbon emissions of these buildings and upgrading them with modern technology and materials will be vital in order to tackle net zero.  

What is retrofitting? 

Retrofitting is, at its core, a method of improving a building to make it more energy efficient. This can include a range of approaches such as minimising energy demand by enhancing thermal efficiency through insulation and glazing or installing new efficient systems and renewable energy technology such as more efficient lighting, solar photovoltaic (PV) panels or heat pumps.  

By installing modern technology, you can ensure an older building reduces its carbon emissions and energy bills as well as improves the comfort of its users.  

The aim should always be to get as close to a new-build’s net zero carbon performance as possible and retrofitting can provide this route by reducing the carbon burden of real estate assets, while also improving the building stock quality. 

There are also a number of retrofit performance standards – including EnerPHit and the AECB’s Carbonlite standard – to help make the journey toward maximising the realistic performance of a building.  

Kettering General Hospital

At CPW, we have recently been supporting Kettering General Hospital to retrofit their healthcare site. The main hospital site previously operated on a steam heating network that was more than 50 years old, ran on temporary steam boilers and required continuous intervention. The existing private high voltage electrical network, whilst still in satisfactory working condition, did not have the capacity to accommodate the redevelopment of the hospital and was supported by aging standby power generation that did not meet current standards for an acute hospital site.

For us, this meant supporting the hospital to upgrade their systems and the delivery of a pathway to net zero carbon, which included large-scale deployment of renewable energy generators. 

Demolition vs retrofitting debate 

We can’t however talk about retrofitting, without discussing demolition. There is a clear tug of war between preserving history and reducing embodied carbon by retrofitting, and the long-term operational benefits of a new build.  

The Architect’s Journal’s RetroFirst campaign reported that 50,000 buildings are bulldozed across the UK each year and that according to the Department for the Environment, Food and Rural Affairs (Defra), 63% of the 200 million tonnes of waste generated in Britain annually is construction debris. 

The case that immediately springs to mind when discussing demolition is the M&S store on Oxford Street, London. The plans by the British retailer to raze and rebuild its flagship store caused public uproar and a media frenzy back in 2022. It resulted in a two-week public enquiry that looked at the role of embodied carbon – the demolition is predicted to immediately release 40,000 tonnes of embodied carbon into the atmosphere – and the case for a retrofit-first approach.  

In July 2023 M&S was refused permission to demolish the store and the fate of the Oxford Street site remains up in the air while the debate over retrofitting vs demolition rumbles on.  

School of Architecture and Built Environment

One of our education projects where retrofit was chosen over demolition was the School of Architecture and Built Environment for the University of Wolverhampton. The new 85,000 sq ft teaching and learning facility was built on the site of the former Springfield Brewery. It was imperative that the new design retained as much of the heritage of the area as possible, including the iconic clock tower building which has been restored, with the addition of new buildings which reflect the site’s historic industrial buildings. The refurbishment has gone on to win RIBA West Midlands Award 2023 and be shortlisted for RIBA Reinvention Award 2023. 

Taking a reuse first approach 

If we’re serious about reducing our carbon emissions, then retrofit makes sense – especially when you consider the substantial embodied carbon and energy savings made in repurposing existing buildings compared with rebuilding. 

Most existing buildings will never be as efficient as new builds – especially our historical and heritage buildings. Nearly a quarter of all UK homes, 6.2m properties, were built before 1919 and almost a third of commercial properties, about 600,000, are historical sites – so it is a huge task to tackle net zero.  

But the size of the existing stock means we must take up the retrofit challenge and make our buildings as sustainable as possible in the fight against climate change. 

For further information please get in touch with the team or follow @CPWengineering on social media.