Two thirds of the whole life carbon of a building is embodied.
The first third is in the creation of the building and the second in the replacement of plant, facades etc. during its life cycle. The superstructure is responsible for about 40% and maintenance and refurbishment accounts for 32% of lifetime carbon.
Every time you demolish a building to build a new one the embodied carbon is lost and a whole new carbon creating cycle begins.
The UK built environment is responsible for around 40% of total UK carbon emissions – that’s almost 166 megatonnes (Mt) of CO2 equivalent per annum – and the construction of a typical 6,000 sq m office creates approximately 4,000 tonnes of CO2e.
In that light, Michael Gove’s decision to reject Marks & Spencer’s plans to demolish and rebuild its flagship Oxford Street store could be seen as courageous and far-sighted. Yet, M&S CEO Stuart Machin begs to differ.
He branded Gove’s decision as “pathetic” and “nonsensical”
Plans for a new ten-storey steel and glass office complex on the site had been approved by Westminster City Council, the GLA and planning inspector David Nicholson, but the Secretary of State for Housing and Levelling Up and his department have rejected that decision on embedded carbon grounds. They have instructed M&S to refurbish and retrofit the existing building instead.
The debate around this project has been emotional with campaigners fighting the company’s plans every step of the way on architectural, historic, aesthetic and sustainable grounds, but Machin also rejects all their arguments as “nonsensical”.
“With retrofit not an option – despite us reviewing 16 different options – our proposed building would have ranked in the top 1% of the entire city’s most sustainable buildings,” he said.
“It would have used less than a quarter of the energy of the existing structure, reduced water consumption by over half, and delivered a carbon payback within 11 years of construction. It is also completely at odds with the inquiry process where the analysis on sustainability, including from independent experts Arup, was accepted.”
He said other developers would find this decision “chilling” and would go into full retreat on redeveloping brown field sites. He accused Gove of chasing “cheap shot headlines” rather than serious policy.
Strong words, but who is right?
Can M&S really believe that erecting a brand new building – whatever its energy performance – is more sustainable than refurbishing and retrofitting the existing one?
The energy efficiency of buildings and products has improved dramatically over the past 30 years, but to protect the global environment more widely we simply must crack the bigger challenge of reducing embodied carbon.
While regulations, greater use of renewables, and improved product performance have all contributed to a steady fall in ‘operational’ carbon, embodied carbon remains big blot on the global horizon and a major reason why the built environment still accounts for more than 40% of total global emissions.
Last year, the parliamentary Environmental Audit Committee called for mandatory whole life carbon assessments and for priority to be given to retrofit and reuse of buildings.
The Committee chairman, Philip Dunne MP, said: “From homes to offices, retail units to hospitality venues, our buildings have a significant amount of locked-in carbon, which is wasted each time they get knocked down to be rebuilt, a process which produces yet more emissions.
“Ministers must address this urgently…baseline standards for action need to be established,” he added – and it appears that Michael Gove has listened to this advice.
The assessment, which the MPs want to see introduced by the end of this year, would calculate the emissions from the construction, maintenance, and demolition of a building, and from the energy used in its day-to-day operation. Holland and France already have mandatory whole-life carbon assessments for their built environment.
For those of us involved in building services, embodied carbon is extremely complex. Our clients often prefer to take the path of least resistance and opt for some sort of ‘statement’ carbon reduction measure like a bolt-on renewable rather than digging too deeply into the maths needed to address the embodied carbon that would make a much bigger difference.
Embodied carbon is ‘boring’
During a BESA webinar last year, Simon Wyatt, sustainability partner at the design consultancy Cundall, said embodied carbon was often regarded as “boring because it is about making things work well throughout the year – it is not about green bling”.
Fortunately, there is starting to be more “excitement” around the topic as more clients and engineers wake up to the fact that without more effort and innovation focused on embodied carbon and lifecycle building performance, we would have little chance of meeting our net zero built environment goals, added Wyatt.
There has also been significant progress in the field including a growing range of digital tools that can help engineers calculate embodied carbon more accurately. The availability of more complete data and better design methods also mean designers can provide more compelling arguments to convince clients of the need for greater investment at the front end of projects to significantly reduce lifetime carbon impact.
CIBSE has produced the first comprehensive guidance for calculating the embodied carbon of building services (TM65) and this has breathed vital new life into the complex process of gathering relevant information from all parts of the supply chain.
It is also following the publication up with a range of methodologies for separate products and systems that will help project teams provide more accurate information to clients so they can make better informed decisions.
More manufacturers are also providing embodied carbon data, which makes it easier to calculate the impact of their products from manufacture up to installation. They are using Environmental Product Declarations (EPDs) or TM65 to provide the data. The RICS Built Environment Carbon Database is also an effective tool for calculating the embodied carbon of complete projects.
The world’s first universal cost standard for reporting embodied and operational carbon in the construction and lifecycle of buildings was also launched last year. 49 professional bodies support the International Cost Management Standard (ICMS3), which is designed to help developers make more informed choices about materials and construction practices, and whether a building should be retrofitted or demolished and rebuilt.
All this important technical guidance means we can approach the embodied issue with more confidence, but all comes to the same basic conclusion: Ultimately, the most carbon friendly approach is not to build at all.
Dr Natasha Watson, senior structural engineer at the consultancy Buro Happold, summed it up during another BESA webinar last year.
“Reuse is better than rebuild. We have more than 600,000 empty buildings – 445,000 of which are residential,” she said “Covid19 has changed how we interact with buildings so we should re-assess how we service them and how we make better use of what is already there. We can repurpose far more.”
She urged engineers to challenge the project briefs they receive more aggressively – and insist on a ‘design optimisation stage’.
“The earlier you tackle this issue, the bigger the potential savings. People are under increasing pressure to deliver projects more quickly and cheaply, but we cannot fully address embodied carbon without proper planning.”
She pointed out that the financial sector was committed to net zero “not necessarily for moral reasons but for business continuity” and that asset owners also recognised their properties would quickly become uneconomic if they did not address this issue. Local authority planners are also stepping up the pressure to address ‘whole life’ carbon before granting planning permission – and the M&S project has just become the highest profile example.
Holy Grail of embodied carbon
Re-purposing an existing building is the Holy Grail of embodied carbon. It is never possible to reuse everything but we can try harder to reuse as much as possible from the foundations up including the superstructure where so much carbon has already been expended.
Building services engineers, like everyone else in the supply chain, also need to design with deconstruction in mind so materials and system components can be recycled, reused, and more easily replaced as part of refurbishment and repair planning.
We also need to do sensible things like use simple, reversible connections wherever possible, so it is easier to bolt in new components without having to remodel and disrupt the whole system. Not rocket science, but also still not standard practice.
The building engineering sector deserves congratulations for taking major strides with product efficiencies and control strategies that reduce carbon in use, but if we are to make progress towards our bigger global environmental goals then embodied carbon will have to be tackled much more vigorously.
While Gove’s decision might ultimately have had more to do with aesthetic appeal than embodied carbon, upsetting iconic corporations and bearing the brunt of their public wrath might have to be the price our policy makers have to pay to finally get traction on this most complex and (sometimes) emotional of issues.