Rethinking retrofit

Retrofit is now firmly established as a central pillar of the UK’s response to both the climate crisis and the evolving demands of the commercial property market. A recent roundtable co-hosted by Howells and the NLA brought together developers, designers and advisors to explore how the viability of reusing office buildings is being reshaped by rising costs, policy changes and market expectations.

One clear theme emerged: successful retrofit strategies are not defined by the scale of intervention, but by understanding the right level of intervention for each building.

Construction costs have risen dramatically in recent years—by as much as 40–50% over the past five years—while commercial values have remained relatively static. Inflation is only part of the story. Regulatory changes, sustainability targets and evolving occupier expectations have all contributed to increasingly complex delivery conditions.

In some cases, retrofit costs are now approaching parity with new build, forcing investors and developers to question how far interventions should go when additional capital investment does not necessarily translate into rental growth.

As a result, understanding the “right depth” of retrofit is becoming increasingly important: identifying where investment will genuinely improve performance and value, and where lighter-touch interventions may deliver a better balance of cost, carbon and commercial return.

This demands a more pragmatic and evidence-led approach. As retrofit-first policies become more widely embedded within planning frameworks, designers need to identify where targeted interventions can deliver the greatest impact, rather than assuming the deepest possible retrofit is always the best solution.

Another consistent theme was the importance of early technical understanding. Existing buildings inevitably carry unknowns, and delays to surveys or technical investigations can create significant risk to both programme and cost. Greater certainty and therefore greater upfront investment in due diligence, is increasingly essential before design strategies are fixed.

This reinforces the importance of integrated teams working together from the outset, combining technical insight, commercial understanding and design thinking to shape realistic and deliverable proposals.

Ultimately, the most successful retrofit projects may not be those that pursue the most ambitious technical interventions, but those that deliver meaningful environmental and occupier benefits while remaining commercially viable enough to happen.

An extended version of this article was first published on the NLA website.