Making Retrofit the Default, Not the Exception

Tuesday 28 April 2026

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Director
Atelier Ten

Making Retrofit the Default, Not the Exception

In this roundtable write-up, Sarah Peterson of Atelier Ten considers how retrofit can become the default approach across the built environment. With early insight, tailored design and a focus on whole-life value, it can deliver high-performing, low-carbon buildings at scale.

Retrofit is often seen as complex and uncertain, but with the right approach, it can deliver lower carbon outcomes, stronger value, and better-performing buildings.At a recent roundtable with colleagues from across London’s built environment including developers, designers, contractors and investors, Atelier Ten explored a straightforward but important question: how do we make retrofit the default, rather than the exception?

Retrofit is still often positioned as a secondary option, more complex and less efficient than new build. In practice, it offers something different, and often better.

Reusing existing buildings allows us to retain the richness and variety of London’s architecture its layers of history, materiality and character rather than replacing it with a more uniform, standardised approach. Many post-war commercial buildings in particular have the structural capacity and adaptability to support transformation, offering a strong foundation for high-performing, contemporary space.

This is not about preservation for its own sake. It is about recognising the value already embedded in our buildings and using design to unlock it.

Designing with the building, not against it

A consistent theme from the roundtable was the importance of early-stage insight. Retrofit projects are inherently specific: every building behaves differently, and successful outcomes depend on understanding those nuances from the outset.

By bringing building performance analysis into the design process early, we can develop energy and carbon strategies that are tailored to the asset, rather than applying standardised solutions. Using dynamic simulation modelling, we create digital twins of buildings to test and appraise options alongside the design team, from the initial stages of the project.

This allows us to balance competing priorities, operational energy, embodied carbon, internal environmental quality, cost and programme and identify the most effective combination of interventions. In many cases, it can mean moving away from blanket approaches such as over-insulating and instead targeting improvements where they have the greatest impact.

Reducing uncertainty through early investment

Uncertainty remains a defining characteristic of retrofit, but it can be managed through early investigation and design.

Investing in surveys, validation and optioneering at the outset enables more informed decision-making and reduces reliance on contingency. It also allows teams to respond to risk with evidence, improving cost certainty and protecting programme outcomes.

This has implications for how projects are structured. Allowing more time at early design stages particularly for testing and iteration often leads to more efficient delivery overall, with fewer changes during construction and better alignment across the project team.

Aligning value and delivery

For retrofit to scale, value needs to be considered more holistically. Capital cost alone does not capture the full benefits of reuse. Whole-life carbon, operational performance, adaptability, sense of place and long-term asset value all need to be part of the assessment.

Procurement approaches also play a role. Introducing fixed-price contracting before sufficient investigation can limit flexibility and increase cost. More balanced, staged approaches, where risk is understood and shared may support better outcomes.

A shift already underway

There is clear momentum across the industry. Clients are setting more ambitious carbon targets, occupiers are prioritising quality and performance, and investors are taking a longer-term view of value.

Retrofit can feel uncertain, but with the right strategy, it becomes a clearer, and more effective route to value. By investing in early insight and design, we reduce risk, unlock potential, and can transform existing buildings into high-performing, future-ready assets.

If London is to meet its environmental and economic ambitions, reusing what we already have will need to become the norm. The conclusion at the roundtable was clear: retrofit is not inherently a compromise. When approached strategically, it can deliver high-quality buildings rooted in hertiage, improved whole-life value, and meaningful carbon savings.