Whole-life carbon assessments – a whole new type of greenwash?

The Greater London Authority (GLA) has nudged WLCAs towards the mainstream in the latest edition of its London Plan. Any scheme involving buildings taller than 30m or providing more than 150 homes must now produce one.

From Oxford Street to the Barbican, architects and developers come armed with detailed WLCAs to back proposals to bulldoze young buildings and to erect steelier, glassier and taller replacements.

Amid the demolition rows all over London, the lack of public confidence in WLCAs should be concerning, given the need for far more of them.

Architect of new scheme Pilbrow & Partners

What the developer’s WLCA says ‘The total whole-life carbon forecast for the building is 134,000 tonnes CO2e. The analysis concludes that the development, using alternative low carbon solutions, could save up to 9,500 tonnes CO2e of embodied carbon at practical completion, compared with not using them.’

Alchemi, a developer which owns the next-door 55 Victoria Street, commissioned its own WLCA report. In a letter, Alchemi sets out its objections to demolition and rebuild at 71 Victoria Street, which include noise pollution and overlooking. However, it also states that the Victoria Property Ventures’ WLCA – which compares retrofit and demolition scenarios – is ‘inaccurate’ and ‘could be considered misleading’.

Source:City of London Corporation/Diller Scofidio + Renfro

Sturgis has found plenty of problems with WLCAs he has scrutinised. A common complaint is about the methodology used, which sometimes puts up a ‘straw man’ argument making unsympathetic assumptions about a refurbishment option – for instance about the amount of demolition that will still be required, or that a retrofit would barely improve energy efficiency.  Regarding the London Wall West scheme, Sturgis puzzles over why the façade of the new-build scheme is assumed to have lower embodied carbon than the façade of the much-smaller refurbishment option. With respect to 1 Museum Street, meanwhile, he questions whether the MEP system really will sequester carbon by producing –1,731kgCO2e over its lifetime and whether the glass façade can be 100 per cent recyclable, given the difficulty of removing sealant from panes.

But WLCAs are about more than up-front embodied carbon: they also consider operational carbon, emissions produced from a building’s day-to-day energy use, as well as in-use embodied carbon, the emissions from future upgrades which will be needed. In theory, this holistic approach allows developers and designers to balance the initial environmental cost of producing a building with its longer-term performance and, hence, assess its sustainability.

Campaign group SAVE Britain’s Heritage

The Twentieth Century Society’s Croft agrees on the need for ‘objective scrutiny, and clearer guidance on collating, presenting and evaluating [WLCAs]’ – adding that ‘with [the current] fundamentally adversarial approach, developers will continue to run rings around the best policy intentions’. 

So are these assessments really being subverted to provide cover for unsustainable business-as-usual development? Are they, in other words, just the latest form of greenwash? And when, if ever, will we have clarity in this complicated area?

It alleges that the whole-life carbon of the consented retrofit scheme would be 20 per cent lower than assumed in the developer’s WLCA, while carbon emissions from demolition – the approximately 700 lorry journeys needed to remove waste from the site – had not been considered.

Source:Pilbrow & Partners, Justin Piperger Photography and Wadsworth3D

Developer Marks & Spencer

‘But if an applicant’s consultants make errors in their submissions there should be legal and financial penalties – as with tax returns. [Councils] should also appoint independent surveyors, paid for by the applicant, to verify complex reports.’

DSDHA’s One Museum Street has meanwhile been subject to a new WLCA – to be published shortly – following updates to its design. Edward Beaver, founding partner at developer Simten, says the new WLCA has been peer-reviewed and has ‘taken account of the [Sturgis] report’. ‘We do believe this proposal is the most suitable response to the project context, taking into consideration carbon from development, through to carbon efficiencies over future decades,’ he adds.

But WLCAs rely on several assumptions about the future. According to Simon Wyatt, sustainability partner at Cundall, the industry is now good at counting embodied carbon – particularly in structures and façades. But he adds that balancing this cost to the environment against operational and in-use embodied carbon in WLCAs is ‘an emerging art’, compounded by a lack of guidance. The assessment will query how long products and components will last before they need replacing – but also raises trickier questions. How much embodied carbon will be involved in replacing a component in 30 years’ time? What will be recyclable 60 years from now? Will steel become net-zero carbon with technological developments? And how abundant will timber be? What will a building’s energy use be in 20 years, and will the grid have decarbonised?

For a technical overview of WLCA methodologies, see The Regs 

Case study: London Wall West (Museum of London and Bastion House)

‘There are a lot of people who have only qualified to carry out this work recently, with little real-life experience,’ he says. ‘When clients pressure them for better numbers, they can get the computer to give them better numbers. Whether they are actually achievable in real life is another matter.’

What the Simon Sturgis-authored report says ‘The current comparison between a “light-touch refurbishment”, which is fundamentally resource and carbon-inefficient, and the proposed new build is not a relevant comparison and is clearly skewed in favour of new build. This has given rise to the incorrect claim that the new build “would outperform a refurbishment of the existing building in whole-life carbon terms within 16 years and possibly less”.’


There are also paradoxes. Under government plans, electricity from the National Grid will be fully decarbonised by 2035. This means that making an existing moderately insulated building very well insulated may not be justified under a WLCA, as the embodied carbon cost of the insulation itself might outweigh future operational carbon savings. However, decarbonising the grid by 2035 itself assumes much-improved thermal efficiency in the UK’s building stock. This complexity allows plenty of room for differing views. Developers pay consultants to carry out WLCAs and there is widespread concern that he who pays the piper calls the tune. Henrietta Billings, director of SAVE Britain’s Heritage, notes that WLCAs are ‘a highly technical, emerging area of policy’ and says she is concerned that ‘few planning departments have the expertise or resources to scrutinise WLCAs with the rigour required’. ‘Without that, it’s impossible for a planning officer to interpret and interrogate the figures presented to them by a well-funded applicant,’ she adds. ‘It’s like getting them to mark their own homework.’

It’s something the government has shown an interest in. It agrees on the need for ‘a standardised method of calculation’ and ‘the creation of a level playing field’. While the government plans to leave industry ‘to find the best solutions’ it will , it says, investigate ‘endorsement of specific standards, methodologies or tools for assessing whole-life carbon,’ in its 2023 consultation.

‘The system is not currently working,’ says Catherine Croft, director of The Twentieth Century Society. ‘Developers have huge financial incentives to pay consultants to argue against retrofit options, while those tasked with assessing the ever-increasing amount of information that descends on them are starved of training and money.’

Campaign group Save Museum Street and Climate Emergency Camden

More speculative questions also arise. Given the urgent need to curb emissions in the face of the climate emergency, is it worse to emit a tonne of CO2 now, rather than half a century from now, when we might have better technology for absorbing CO2 emissions? If so, how should that be weighted in a WLCA?

Visualisation of Selkirk House

‘Local authority, GLA and national policies all call for rapid decarbonisation to tackle the climate emergency,’ he points out. ‘But planning guidance is never clear that demolition must be a fall-back option, with refurbishment as the default mode of development. That is a big part of the problem.’

Sturgis was also commissioned by Barbican Quarter Action, a resident-led group fighting Sheppard Robson and Diller Scofidio + Renfro’s plans for two new office blocks at London Wall West, part of the Barbican. The group has now accused the City of London of using ‘misleading data’ to justify the demolition of the existing Museum of London complex and Bastion House.

‘He [Sturgis] does not acknowledge the complexities or shortcomings of the three individual buildings on the site – buildings that are poorly interconnected and of limited quality,’ says Pilbrow.  ‘He fails to provide any alternative calculations, nor does he acknowledge that Arup’s work has been reviewed in detail by specialists at both the local authority – Westminster –and by the GLA.’

Anna Pamphilon, director at Pamphilon Architects and an Architects Declare committee member, reiterates that ‘there is a big skills gap in industry’ and says it is ‘important that architects become literate in WLCAs’.

As for Sturgis, he insists it should not be left to developers and their consultants to spell out the common-sense need for a retrofit-first approach in London and other cities.

Visualisation of Pilbrow & Partners’ M&S Oxford Street proposal looking east

What the developer’s WLCA (by a City of London-led team) says ‘The analysis concludes that retaining existing building fabric does not achieve the most sustainable outcome for this transformative and strategic site. The redevelopment option would perform 10 per cent better than the retention option [on kgCO2e], which would still require a significant carbon investment.’ 

The City of London also sticks by its WLCA, which argued that Bastion House cannot be retained due to the risk of ‘disproportionate collapse’ – a claim strongly contested by Barbican Quarter Action Group, which commissioned its own independent structural report.

What the developer’s WLCA says ‘The whole-life carbon forecast for the proposed development is 106,000,000 kgCO2e over a 60-year period – or 89,000,000 kgCO2e taking into account for decarbonisation of the grid.’

Others have expressed similar concerns. Jim Monaghan is co-founder of MBH Architects and campaigner at Save Museum Street – which is opposing DSDHA’s plans to demolish the 17-storey Selkirk House in Holborn and replace it with a new tower. He agrees that developers are ‘extremely adept […] at commissioning greenwash reports that say their schemes are the best thing since sliced bread regarding reducing carbon emissions’. Campaign groups and even rival developers have turned to commissioning their own whole-life carbon reports to scrutinise an applicant’s assessment. SAVE Britain’s Heritage and Save Museum Street have both commissioned reports by Simon Sturgis – one of the few genuine experts on WLCAs – on M&S Oxford Street and 1 Museum Street respectively.

Existing building 17-storey hotel block built in the 1960s

What the Simon Sturgis-authored report says ‘This assessment […] gives an incorrect impression of the carbon impacts of the proposed scheme. It appears to be designed to specifically rule out retrofit as an option to ensure the proposed demolition and redevelopment, rather than to positively examine options for repurposing and retrofit.’

Case study: M&S Oxford Street

It is an issue that is likely to be increasingly important to architects outside the capital. In an effort to tackle embodied carbon (the emissions released by the mining, production and transportation of building materials), the government last month hinted it could mandate WLCAs on some or even all buildings following a consultation next year, with regulations seeking to cap embodied carbon likely to follow.

‘Fully retaining the existing buildings is not a suitable option, due to significant structural issues, fire safety, very poor energy performance and the limited uses which would be possible at the site,’ the City of London Corporation has said.

London Wall West

Existing buildings Bastion House, a 17-storey, 1960s office block, and Museum of London Complex, a three-storey, 1970s museum refurbished in 2010. Both designed by Powell & Moya.

Architect of new scheme DSDHA

Developer BC Partners and Simten

WLCAs forecasting how much CO2 a scheme’s backers think will be produced from a building’s creation through to its demolition and possible re-use now accompany applications for most major developments in London. They were meant to usher in a new era of low-carbon development. But instead, campaigners claim, they are being manipulated in some instances by canny developers able to exploit the lack of industry and planning know-how to spuriously justify demolition over refurbishment.

In response, campaigners are shelling out to produce their own rival WLCAs to question the assumptions in – and the intent behind – developers’ calculations. It is a foggy, CO2-filled battlefield. 


‘Redevelopment allows for a larger, more efficient scheme, and will deliver lower whole-life carbon emissions in comparison with the part-demolition, part-retention option, per m2.’

There is no one-size-fits-all way of pinpointing how much CO2 will be released by a building over its lifetime. Whole-life carbon assessments (WLCAs) are an evolving, complex and imperfect science. For many, they are tortuous and labyrinthine, created by some hard-to-fathom alchemy. And they are causing more and more disputes, especially across London.

Existing buildings 1929 Orchard House, 1960s 23 Orchard Street and 1980s Neale House. All four or five storeys

These are not the only schemes with controversial WLCAs. Another is Trehearne Architects’ plans to demolish 71 Victoria Street, a 1990s office block in Westminster, and replace it with a new hotel. The proposal – for Victoria Property Ventures – is an update from Trehearne’s earlier, consented, plans to retrofit the existing building into a hotel.

Architect of new scheme Sheppard Robson and Diller Scofidio + Renfro

She points out that ‘accurate, proportionate and non-biased WLC reporting to precisely set standards will be imperative if we are to cut carbon emissions and legislation will play a key part in ensuring that this happens.’

What the Simon Sturgis-authored report says ‘The London Wall West WLCA appears to be designed to pay lip-service to the requirement to examine retrofit […] The analysis concludes that retaining existing building fabric does not achieve the most sustainable outcome for this site. On the information provided in the report this is clearly not the case.’

Case study: One Museum Street (Selkirk House)

For Sturgis, WLCAs remain a useful tool to encourage developers and architects to think about the carbon impact of their design choices. And he says that, although there are mistakes in the WLCA calculations he reviews, it’s the reports accompanying them that are more likely to be misleading. This is ‘no coincidence or mistake’, he adds. There may be hundreds of millions of pounds of potential profit on the line, with new build schemes unconstrained by existing fabric and, typically, much larger.

Developer City of London

Charlie Baxter of Alchemi believes that there should be more accountability over WLCAs. ‘It’s clear that planning officers and GLA officials rely on applicants being open and honest,’ he says.

Wyatt says that consultants, who may lack skill and experience, are often ‘pressurised into improving the performance’ on WLCAs.

Campaign group Barbican Quarter Action 

While he says retrofit is almost always the lower carbon option, Wyatt also urges developers not to focus solely on carbon calculations and to justify demolition and new build ‘in terms of its wider sustainability, social or economic value’.

And, while the rolling-out of more WLCAs may elicit concerns in the short term – given the current problems highlighted by campaign groups – it will also produce a vast amount of data that will help standardise calculations and make assessment easier. ‘WLCA is not sophisticated enough yet, but we need to keep doing it so we can get sophisticated at it,’ explains Wyatt.

Some of those involved in producing WLCAs challenged by the likes of Sturgis are prepared to defend them, however. Arup declined to comment on Sturgis’s suggestion that the light-touch refurbishment outlined in its WLCA for the M&S Oxford Street store was deliberately designed to fail against the demolition and rebuild alternative (see page 18). But the project’s architect, Fred Pilbrow of Pilbrow & Partners, says Sturgis is being ‘unfair’.