Embodied Carbon: New Build vs Rebuild

Phil Winkles, Partner and Head of Professional Services, North at Matthews & Goodman looks at the debate about reducing the built environment’s contribution of over 40% of annual CO2 emissions.

 Is it my imagination or has the passion of COP26 cooled?

Of course, other priorities – from selecting a new Prime Minister, to trying to manage the hike in energy prices and cost-of-living crisis, as well as navigating interest rates at home and wrestling with the Ukraine issue abroad – have pushed this issue off the top of the Government’s agenda.

However, The Climate Change Committee, the Government’s official advisors, recently described the Government’s current achievements of reducing climate warming emissions as “shocking”.

As a member of the built environment community, for me the ‘carbon issue’ is far greater than home insulation, carbon offsetting and tub-thumping commitments to reaching Net Zero by 2050.

The Environmental Audit Committee’s recent recommendation for the introduction of mandatory whole-life carbon assessments for buildings (in planning guidance and building regs) – is one of the most critical contributions to the whole debate. The Committee’s advocacy of including an assessment of locked-in carbon and the fact that embodied carbon is wasted each time a building is knocked down to be rebuilt, is thought provoking – but probably not popular with many involved in new-build projects.

This issue came to the fore when Michael Gove, then Secretary of State for the Levelling Up, Housing & Communities exercised his authority and ‘paused’ the proposal to demolish and rebuild M&S’s Oxford Street store.

The subsequent Public Inquiry will consider whether the intended plan will release over 40K tonnes of CO² into the atmosphere (as anti-plan campaigners claim) or, whether redevelopment of the existing building will create additional carbon emissions and use 25% less energy – as the retailer and its architectural consultants (Pilbrow & Partners) claim.

Should we encourage the greater use of low-carbon materials, such as timber and recycled steel?

Should we, like France and the Netherlands, focus much more on re-use and retrofit in our national strategy to tackle embodied carbon?

Is Permitted Development, whilst reducing bureaucracy and eliminating unnecessary red-tape related delays (in ‘getting building done’), the correct tool to support the re-use of buildings.

Will the decision not to retrofit or rebuild increase the amount of embedded carbon in the built environment?

Developers promoting demolition and rebuild will argue that no two projects are the same and starting with a clean sheet of paper is more cost-effective and allow energy-saving strategies to be designed into the new building.

On the other hand, retention and retrofitting supporters say that there is ‘limited evidence’ of the Government’s claim to be actively promoting ‘reuse’ and retrofitting.

Talk of introducing mandatory ‘Circular Economy* Statements’ in pre-demolition audits on planning applications would increase the ‘red-tape’ factor, while leading to more transparency and accountability on sustainability issues.

For the rebuild communities’ the most evocative argument that increasing awareness of the environmental, sustainable and financial benefits of high quality rebuild solutions will be a game changer. Why? Because greater ‘consumer’ awareness will drive explicit ESG goals and ambitions from investor, shareholder, employee and clients demand leading to rebuilding rather than demolish-and-build with.

The high profile of Net-Zero and the need for stringent energy management has changed the conversation in boardrooms across all sectors and across the globe. This is what the rebuild and retrofit community want to achieve and with the emergence of a market where occupiers are drawn towards repurposed accommodation, rather than new build alternatives.

Of course, there is no option but to retrofit certain buildings (such as historic and listed structures), but perhaps rebuilding and retrofitting should be the first option we consider, rather than automatically opt for a ‘knock it down and start a fresh’ strategy – which many feel is a default position.

It might have other benefits when many are facing materials shortage and the subsequent hike in materials’ prices (albeit for many conversion projects achieving energy targets is not straightforward or cheap).

Consider the £160m speculative redevelopment of BT’s former City of London HQ – allegedly one of the largest redevelopments in London’s history. According to Mace, the main contractor, working with the existing structure as opposed to a full demolition and build, will halve the carbon footprint of the project. In addition, retaining the core structure will save 465kg of CO² psm. Mace also intends to recycle existing building materials and reuse over 1,500 tonnes of Portland stone and granite.

Replacing the concrete piles with a more environmentally friendly steel pile solution will save a further 296 tonnes of carbon.

If the project achieves its ambition of securing BREEAM Outstanding certification, WiredScore Platinum and NABERS 5* Excellent rating, this really will not only prove the ‘poster structure’ for the redeveloping cause, but might also be cited in years to come as the watershed project in the sustainability debate.

_{*Circular Economy: a model which integrates production, distribution, consumption, as well as reusing, repairing, refurbishing and recycling materials and products as long as possible. This waste reduction strategy was originally inspired by nature’s ecosystem in which water and nutrients are continuously recycled.}