A pilot version of the standard was unveiled last year and is currently being tested across 228 projects. A final version of the standard will be published later this year, at which point assessors will be ready to verify completed projects as net zero carbon.
The standard aims to combat greenwash by creating a single agreed definition of a ‘net zero carbon’ building. It is backed by industry bodies including RIBA, RICS, LETI, CIBSE and the UK Green Building Council.
But, writing in the AJ, Simon Sturgis of Targeting Zero has called for ‘a major edit’ of the standard, arguing that it ‘unintentionally encourages demolition’ as it provides easier embodied carbon targets for new builds than for retrofits and does not provide whole life carbon targets.
The AJ spoke to three other experts who shared his concerns: AAB architects’ director Alice Brown, Climatise managing director Chris Brown and Cundall’s head of sustainability Simon Wyatt (see full comments below).
Strugis, a zero carbon expert who has advised Parliament, RICS, RIBA and on the development of the standard itself, said it should ‘focus on two limits for every project; energy-use in kWh and whole life carbon in kgCO2e,’ adding that there should be ‘a single combined limit for both new build and retrofit for every use type’.
He points out that the retrofit square metre limits are up to 30 per cent lower than new build, making them more difficult to achieve.
He adds that the standard focuses on square metre rates (kgCO2e/m2): ‘What this ignores is that it is the total carbon emissions of a development that really matter.’
Wyatt agreed that the standard ‘may to lead to unintended demolition’ as ‘there are currently separate limits for retrofit projects and new buildings, as well as the fact that projects are only assessed against intensity targets not absolute emissions’.
AAB architects’ Brown meanwhile said the standard ‘is an attempt to align with the UK’s net zero strategy’ — rather than truly hitting net zero carbon. She added that this strategy ‘is itself inadequate and failing to deliver’ as it only focuses on emissions generated in the UK.
Chris Brown said that the standard has been ‘deeply flawed, strategically, from the beginning’, as it ‘didn’t focus on carbon’ but instead includes ‘out of date’ energy limits which ‘creates the bizarre incentive to do things that are bad for the planet’.
In a detailed response (see below) David Partridge and Will Arnold of the UKNZCBS said the standard was ‘designed to encourage retrofit, not demolition’, adding that whole life carbon limits are not in the standard as there was a lack of data with which to set ‘robust and fair targets’.
‘There is a risk to introducing WLC limits that are not robust, that could allow today’s emissions to be ‘balanced’ by promises to reduce carbon in the future,’ they said — adding that they plan to introduce lifecycle carbon limits in the future.
Chris Brown, Climatise
Simon Sturgis is right to criticise the standard, and I say that as someone who contributed a considerable amount of time to the embodied carbon and housing task groups and who has huge respect for the other people involved in creating it.
The standard was deeply flawed strategically from the beginning.
First, it didn’t focus on carbon. The out of date inclusion of energy limits creates the bizarre incentive to do things – like overinsulating – that are bad for the planet.
Second, it tried, on almost no reliable data, to come up with limits for a large number of building types. But each building is different.
Despite the huge amount of effort that has gone into it, I would scrap it and replace it with something that is more 21st century than 19th century.
What we need instead is a standard that simply requires honest, digital Environmental Product Declarations, and smart meter data, for every building. These two data sets can be automated to deliver a carbon footprint for every building in real time – both absolute and per m² – and energy if desired.
We can then compare these against whichever economy wide decarbonisation curve we choose.
And a new name is needed – the current ‘standard’ is many things, but ‘net zero’ it is not.
Simon Wyatt, Cundall
One of the biggest concerns is the standard may lead to unintended demolition, as there are currently separate limits for retrofit projects and new buildings as well as the fact that projects are only assessed against intensity targets not absolute emissions.
For example if a developer is looking to do a deep retrofit of an office its upfront embodied carbon limit is 600kgCO2/m2 [GIA], whereas if they demolish it and replace it with a new building the upfront embodied carbon limit is now 735kgCO2/m2 [GIA], which on paper looks like a 23 per cent increase but the new building could easily be 50 per cent bigger than the retrofit increasing the absolute emission by 84 per cent.
I am not against separate targets for retrofit projects and new buildings but the new building should always be the more onerous to avoid unintended consequences.
I generally agree with Simon’s proposal, especially around the unintended consequences of separate retrofit and new build limits. The whole life carbon elements in general are covered but could do like the rest of the document with some clarifications and simplifications.
Of more of a concern is the lack of a verification process for new buildings on construction — the standard is currently in an in-use only standard which requires at least 12 months of operational data — as well as a lack of a delineated approach to multi-let buildings. This is currently under review and is urgently needed.
Alice Brown, AAB architects
The standard does not refer to a fixed amount of emissions to fit within carbon budgets set by the Climate Change Committee. Instead, it offers rates of up-front carbon in construction per m2, with no limits on the build area, and no limits for Whole Life Carbon.
Without constraining development within carbon budgets, per sector, the standard enables growth of the construction industry to continue as usual and does not address this prime cause of climate and ecological breakdown.
There are major difficulties with developing meaningful accreditation in the terms adopted by the standard. The UK’s carbon budget is for emissions generated in this country. That does not align with the proper way of measuring embodied carbon from construction, namely the RICS whole-life carbon assessment methodology which correctly includes the considerable emissions caused by the resource extraction and material manufacture outside of this county. More than 50 per cent of the UK’s carbon footprint is attributable to imported goods.
As it stands, calling this a ‘net zero’ standard is a misnomer; it is an attempt to align with the UK’s net zero strategy, which is itself inadequate and failing to deliver. In addition, the standard does not address the necessity of cutting resource extraction to lessen environmental degradation.
Instead of accepting industry greenwash, we must do all we can to avoid unnecessary demolition of buildings. Wherever possible, we should spend the UK’s carbon budget on repair, refurbishment and retrofit.
Simon’s article raises concerns about the Standard, questioning its structure and its potential impact. We welcome such scrutiny and constructive debate – it has shaped the Standard from the very beginning. However, it’s important to address some of the misconceptions and provide clarity on the thinking behind its framework.
Whole life carbon
The Standard is fundamentally built on whole life carbon (WLC) principles, and the methodology aligns with the RICS PS. The current version of the Standard sets limits on upfront carbon and energy use, which were derived from a carbon budget for UK buildings (allowing for both domestic and imported emissions) and the UK’s renewable energy capability. Importantly, enough data was available for these metrics that we felt robust limits could be set. The same was not true of other metrics. The Standard does require WLC to be reported, and future versions may well set an overall WLC limit, but sufficient data is not yet available for this.
Upfront carbon emissions can be accurately assessed and verified at the point of construction. While lifecycle embodied emissions are important, industry data for these later-stage impacts is currently too inconsistent to be able to set robust and fair limits. When data improves, we plan to introduce life cycle embodied carbon limits, at which point WLC emissions would be effectively limited by the standard, even if not through a single limit. The same is true of in-use fit-out limits, which will be further rolled out as data comes in, and are already applied to offices in the Pilot.
Energy use limits (rather than operational carbon) are set because reducing energy use is required for the electricity grid to be able to decarbonise. Without this, the grid will not become near-zero as early as planned, requiring additional infrastructure (with associated environmental impacts) to do so. Communication and verification are also more transparent when using energy limits, as building performance alone is being considered, independently from the wider system: grid carbon factors vary, while energy use is directly measurable and directly drives design and operational decisions.
Finally, we recognise that the time value of carbon also matters – emissions today cause more harm than those in the future. There is a risk to introducing WLC limits that are not robust, that could allow today’s emissions to be ‘balanced’ by promises to reduce carbon in the future.
Retrofit: encouraged, not penalised
Simon raises concerns that separate limits for retrofit and newbuild may unintentionally favour demolition. The data does not support this. Retrofit projects consistently achieve lower upfront emissions than newbuilds. Data from the Greater London Authority during the Marks & Spencer inquiry showed 20-30% reductions below newbuild levels for ‘light extension’ retrofits, with pure retrofit performing even better.
During public consultation in 2023, industry was also given the option to support either separate or unified limits for retrofit and newbuild. 55% supported the separate limits, 35% were neutral, and only 10% supported a unified approach. This suggests that most of the industry understands and supports our rationale.
Once retrofit limits were set, they were then reviewed and adjusted for achievability by more than 350 expert contributors.
It’s also worth noting that where extensions are added to retrofit schemes, those areas are treated under the newbuild limits. This ensures that more intensive interventions are fairly assessed.
We want to be absolutely clear: the Standard is designed to encourage retrofit, not demolition. Limits for new buildings are set to be ambitious and aligned with best-practice, while those for retrofit projects are set at a level that we believe a large majority of buildings can comply with. This gives retrofit a clear and achievable pathway to compliance, while ensuring newbuild projects are held to equally rigorous standards.
Specificity is not a flaw – it’s a strength
We have strived to make the Standard as simple as we can, while covering all the necessary components of whole life carbon, and being specific enough that it could be verified against, preventing greenwash. Technical detail adds complexity, yes, but that detail is also essential: specificity is what gives the Standard credibility.
However, we understand the concerns around complexity, which is one of the reasons why the Standard has been launched as a pilot – now being tested by more than 200 real-world projects. In an early survey, 60 per cent of these pilot testers said they found the Standard easy to use.
We also acknowledge the concern regarding delineation in multi-let buildings. This is a known area of complexity, and one the Standard is actively addressing. The need for clear delineation was identified in the pilot version and is currently under development by the team.
We continue to welcome all feedback, including proposals for ways the Standard could be simplified without compromising its integrity. We encourage anyone with specific suggestions to contribute via the feedback portal.
A platform for action
It is worth reiterating that the Standard is not a static document. It was always intended to evolve, and the pilot phase is a key part of that. But even today, it provides the most comprehensive and usable framework the UK has seen for aligning building performance with a 1.5°C carbon budget.
Since its launch, the Standard has been met with extraordinary support from across the construction sector. It gives asset owners, designers and contractors a shared set of metrics for understanding and reducing emissions. And crucially, it empowers informed decision-making – from concept design to construction delivery.
To claim that the Standard is misaligned with WLC principles, or that it encourages demolition, is to overlook the careful balancing act behind it – one that considers data availability, verifiability, time horizons, and industry readiness. The approach is not perfect, but it is practical, effective and grounded in the realities of today’s construction environment.
We encourage continued dialogue, and we urge the industry to get behind this collective effort – to share data, refine, improve and implement the Standard, so that we can deliver the change that the world’s ever-worsening climate needs.
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