Much of the early commentary on this milestone has understandably focused on new development. For our clients, however, the more significant point is that the Standard was built from the outset to cover existing buildings and retrofits, not just new build, across 13 sectors. For a market where the overwhelming majority of the buildings we’ll be occupying in 2050 already exist, that is the more consequential story.
Why this matters for existing assets
New development starts from a blank sheet of paper in pursuit of net zero. Existing stock does not. It carries embodied carbon already spent, systems that were never designed around a whole-life-carbon budget. In many cases, planning and heritage constraints that shape what retrofit is even possible. Verification gives that stock something it has lacked: a consistent, evidenced way to demonstrate genuine performance improvement, rather than relying solely on the modelled, design-stage claims that have historically dominated the conversation.
That shift, from predicted to measured, in-use performance, is what gives the status its credibility. It also means alignment isn’t a one-off badge. Annual re-verification is required to retain the status, placing ongoing asset management on an equal footing with the retrofit works themselves.
Our seat at the table
We’ve followed this Standard closely because we’ve supported in shaping it. As a member of the Top-Down Task Group during its development, I worked on how national carbon budgets and science-based targets translate down to individual assets - precisely the foundational framework that now underpins verification. I’ve also led pilot projects on behalf of two clients, IM Properties and McCormick and Company through the rigorous pilot testing programme.
Combining planning and development expertise with the sustainability specialists who helped write the rulebook is where we can add the most value as verification beds in. Our work on retrofit and refurbishment includes advising owners on the trade-offs between demolition and reuse, navigating heritage constraints on retrofit schemes, and increasingly responding to local plan policies, London's draft Plan among them. The message is clear: whole-life carbon and in-use energy performance are now the material considerations.
What owners of existing assets should be doing now
Verification currently sits with Bureau Veritas alone, though training and accreditation for wider industry verifiers opens in 2027. Where we spend our time, working with our clients, is earlier in that process:
- Stress-testing the evidence base: Before committing to a verification submission, we test existing buildings against the Standard's requirements so that gaps in metering or embodied carbon data are found early. Our most common finding: metering for existing buildings is often only available at a whole-site level – inclusive of external lighting, EV charging and other loads outside the building itself; which leaves the building's own performance impossible to isolate, let alone evidence.
- Shaping the Standard: Evolution of the Standard over time is critical, and industry engagement invaluable in that endeavour. it's ultimately a standard for the industry, built by the industry. The pilot testing programme is a good example of real-world application shaping change: on behalf of our clients, we fed back that the inclusion of process loads and the inability to avoid fossil fuels in certain manufacturing applications made the Standard unfeasible to adopt as drafted, and the Technical Steering Group responded by positively addressing both areas of concern.
- Balancing real-world implications: Not every tension between the Standard and real-world delivery resolves as cleanly. On Storage & Distribution schemes, we've raised directly that the 65–75 kWh/sq m building footprint renewable generation target effectively requires covering the entire roof once rooflights are accounted for - a cost that's hard to justify on unconditioned buildings with low, often weekday-only demand. The alternative approach, matching annual PV production to annual consumption, creates its own distortion: on one project, meeting 30% of annual demand achieves 70% on-site consumption, whilst aiming for 100% of annual demand pushes on-site consumption down to just 30%, with the rest exported, which creates its own viability challenges. We've suggested an hourly, rather than annual, demand-matching metric as a fix: a Building Standard should arguably be judged on how much of what it generates the building actually uses dynamically.
None of these ongoing discussions detract from what verification represents: for the first time, owners who have invested genuine effort in lowering carbon emissions have a credible, independent way to prove it. Any friction is to be expected with a genuinely new standard bedding in - and, if anything, evidence that the industry is engaging with the rigour this moment demands.
The bigger picture
Verification won’t be right for every asset on day one, and for many owners the more urgent task is simply understanding what the evidence requirements mean for their portfolio. But the direction of travel is clear: net zero claims for existing buildings have moved definitively to something that has to be earned, evidenced and maintained.
For a conversation about what UK NZCBS verification means for your existing portfolio, get in touch with Snigdha Jain, Director, Head of ESG.
31 July 2026
