Retrofit or regret: Why the fastest way to reach net zero is to fix what we already have

Volatility in global supply chains, resulting in a choking of oil supply, something brought into sharp focus by the US/Israeli attacks in Iran, shows just how vulnerable our energy security remains.

While influence in geopolitics remains beyond most of us, there is a more straight-forward means for us to control and make the most of the energy we use. Retrofitting old or energy-hungry buildings is a way to do this.

As a society, and within the construction industry, we have an urgent obligation to create a much more sustainable future. That is now underpinned by law. The UK is committed to achieving net zero greenhouse gas emissions by 2050, with demanding interim targets well before then. Buildings are central to this challenge, accounting for a significant proportion of energy use and lifetime carbon emissions.

While new buildings matter, they represent only a small fraction of total stock added each year. Even the best performing new developments cannot deliver the pace or scale of carbon reduction required unless existing buildings are addressed decisively.

Read more:

• Housing minister suggests £10,000 retrofit bill for homebuyers is ‘minimal’
• Neighbours band together to tackle energy bills and show how climate action starts at home
• ‘Draughty and inefficient’ homes are worse for climate than cars

Retrofitting existing buildings offers the fastest and most effective route to carbon reduction in construction. Crucially, it allows us to retain and repurpose existing structural frames and foundations, the most carbon intensive elements of any building.

The concrete and steel already in place represent a substantial investment of embodied carbon. Demolishing them and starting again releases that carbon burden all over again before any operational savings are realised.

Reusing sound structural frames while upgrading internals, services and façades preserves that embedded carbon and delivers immediate reductions in energy demand. This approach is particularly relevant in larger, more complex buildings, where robust structures were often designed for long service lives and can support significant performance upgrades. 

Modern retrofit is about far more than adding insulation or upgrading interiors. To be effective and durable, interventions must address the full range of performance demands placed on contemporary buildings. Many of the levers we can pull on converge around how a building’s external envelope performs.

Thermal efficiency, structural integrity, and airtightness are fundamental, but so too is solar gain management, ensuring buildings avoid overheating as summers become warmer. Acoustic performance is critical in denser urban environments, where noise can directly affect health and wellbeing. Durability ensures that retrofit solutions last for decades, not just a few years. For many buildings these performance demands are ultimately resolved at the façade, the critical interface between internal environment and external conditions.

Fire performance is paramount, particularly in taller residential and commercial buildings. Façade systems, materials and detailing must meet stringent fire safety requirements while working in harmony with thermal and structural upgrades. Retrofit must improve safety, not introduce new risk.

Aesthetics also matter. Buildings shape how people feel about where they live and work. Sensitive, well designed upgrades can transform tired façades, reinvigorate residential and commercial environments, and extend the relevance of existing buildings in modern cities.

Regulation is rapidly catching up with reality. Energy performance standards are rising, and expectations around safety, carbon reporting and building performance are becoming more explicit. Poorly performing buildings are increasingly at risk of becoming economically and socially obsolete, harder to occupy, insure or finance.

For owners of older buildings, particularly larger assets, retrofit is becoming a necessity rather than a choice. Those who act early can protect asset value and reduce long term risk.

Delivering retrofit at scale requires a shift in how projects are planned and delivered. Modern methods of construction, including off site manufacture, allow façade systems and components to be produced with greater consistency, less waste and reduced disruption on site. This is an important consideration for occupied buildings.

Digital tools play a supporting, rather than dominant, role. 3D design and BIM (building information modelling) help teams understand existing buildings more accurately before work begins. Reality capture, scanning technologies, and thermal, acoustic and carbon modelling allow retrofit strategies to be tested and refined, reducing risk and improving outcomes.

The introduction of AI is beginning to assist in analysing complex data sets and exploring optimisation options, but its role remains an enabler rather than a replacement for engineering judgement. 

Inefficient buildings cost people money, undermine comfort and contribute to poor health. Retrofit reduces energy bills, improves internal environments and makes buildings safer and more resilient. At the same time, it supports skilled employment and long term capability within the construction sector.

With most of the buildings of 2050 are already standing today, the next decade will be decisive. The materials, methods and expertise already exist. What is required now is urgency and intent.

Retrofitting, and intelligently repurposing, existing buildings is not a secondary option. It is the central task if we are serious about meeting net zero targets and creating places that are safe, durable and fit for the future.

Eugene Clarke is CEO of Clarke

Do you have a story to tell or opinions to share about this? Get in touch and tell us more. 

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