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What architects can do to help reach net zero

Embodied carbon and how best to use limited resources took centre stage at the RIBA’s most recent Smart Practice conference

Rammed earth on Bushey Cemetery, designed by Waugh Thistleton Architects.
Rammed earth on Bushey Cemetery, designed by Waugh Thistleton Architects. Credit: Lewis Khan

The overarching theme of the RIBA’s 2023 Smart Practice conference – creating sustainable outcomes through craft and materials – was split into sub-themes: ‘Specifying for the future’ on day one and, on day two, ‘Working towards net zero’. The focus was embodied carbon and a more intelligent use of limited resources.

Contributions ranged from big-picture, planet-wide reviews of architects’ power to influence change, to an intense, hyper-focused examination of the poetic qualities of rammed earth in Bushey Cemetery (by Andrew Waugh of Waugh Thistleton Architects).

Compère Jess Hrivnak, RIBA’s practice technical adviser (sustainability), kicked off both days with overviews of net zero – of architects’ future role and where we are on agreeing a definition. She suggested architects can limit upfront carbon costs via specifications. She said the London Plan and the industry-led Part Z proposal (in which building regulations would ensure mandatory assessments and reporting of whole life carbon) would support that ambition.

She encouraged everyone to send in-use data from their projects to the Built Environment Carbon Database to inform policy-making going forward.

Next day, Hrivnak brought us up to speed on progress with the UK’s Net Zero Carbon Building Standard, another industry-led collaborative initiative. To combat greenwash, the free, voluntary standard will harmonise definitions of net zero by setting science-based limits for carbon emissions and performance targets for buildings in use.

Breaking our addictions

The talks that followed began with a look at our ‘addiction’ to fossil fuels, raw material consumption and waste, by Duncan Baker-Brown, architect and author of The Re-use Atlas. In the face of catastrophic warming, mass extinctions and a growing human population, the effectiveness of architects’ actions will depend on ‘rewiring the global economy.’ When international construction builds the equivalent of Greater London every six weeks (pointed out Simon Sturgis of Targeting Zero) it’s clear that this dramatic prognosis is no exaggeration – not least because it was made by ex-governor of the Bank of England Mark Carney who is not known for hyperbole.

Several presenters rehearsed the industry’s disproportionate contribution to the threat to sustainability: each year it extracts 65 billion tonnes of raw materials; its share of landfill waste is 35%; its contribution to carbon emissions was estimated at 40%–50% or more.

Architects’ natural desire to improve these figures should temper ambition with reality. Phil Obayda of Skidmore Owings & Merrill (SOM) revealed that our decisions hold sway over a mere 2.5% of the construction industry’s total emissions. Cutting those emissions would be worthwhile but is unlikely to solve the sustainability crisis. For that, Obayda argued, architects should add more targets to their list of desirable outcomes. These fall into three categories: material alchemy, future of the old, and beyond boundaries.

Given that society needs more buildings, net zero cannot be met by using biomass materials alone. But nor can we keep increasing our use of concrete and steel. Instead, we need novel renewable materials. To that end, SOM is partnering with Prometheus to develop a bio-block that eliminates cement – the key carbon-emitting element in most CMU blocks.

We should also be designing buildings for longevity and multiple uses. Judging by the last 27 years, the purpose of many of the single-use buildings we build in our cities today will need to change in the 27 years to 2050 – the deadline to reach net zero. For this, architects will need to rethink how they design buildings’ least adaptable parts – the structure.

His final fix is effectively to sweat assets, not just for financial gain but to share resources for community benefit – rather as trees do in a forest. This means buildings (such as SOM’s Urban Sequoia concept) that are net carbon negative because they generate onsite renewables and sequester carbon using biomaterials.

Ways to influence the future of sustainability and go beyond the red line: SOM’s Urban Sequoia concept is designed to be net carbon negative through onsite renewables and carbon sequestration through biomaterials.
Ways to influence the future of sustainability and go beyond the red line: SOM’s Urban Sequoia concept is designed to be net carbon negative through onsite renewables and carbon sequestration through biomaterials. Credit: Som L Miysis

Definitions and strategies

For anyone wondering what biomaterials are, James Rixon of Architects’ Climate Action Network (ACAN) provided a useful definition. They have good breathability, hygroscopicity and evaporation, and:

•    are abundant and renewable

•    can be extracted with minimal ecological damage under regenerative land stewardship

•    require minimal processing (ie, have low embodied carbon)

•    are healthy and non-toxic

•    can be sourced responsibly

•    can easily be reused and recycled or returned to the earth.

Aurore Baulier and Stephanie Crombie, also from ACAN, discussed the numerous sources of good information supporting the use of biomaterials – details that are also on the ACAN website.

Presenter after presenter outlined strategies for sustainability. Baker-Brown emphasised the importance of designing for disassembly, which requires you to draw and quantify differently – and avoid glue. He also highlighted the state of play in urban mining, which he dubbed ‘reprocessing the anthropocene’, citing the experimental Waste House project that reused duvets for insulation and crushed oyster shells for tiles.

Justin Taylor of Autodesk added some detail to the urban mining concept, reviewing what it would take to establish Buildings-as-Material-Banks (BaMBs) in reference to the EU-funded BuildChain platform. As well as designing for disassembly, a workable system needs a centralised database of what material is where, its grade and characteristics, and so on. The liabilities and responsibilities for maintaining and managing the data must be established as a key to its success.

Kirstin Assheton and Christian Dimbleby of Architype dispelled a few myths about Passivhaus’s suitability for larger scale projects, citing their Harris Academy Sutton and Currie Community High School projects. Tips for success included simplifying construction for buildability, testing for airtightness on mock-ups early, and, if using a steel frame, getting analytical about every last detail.

Simon Sturgis warned, though, that Passivhaus is not always the answer. On refurbishments, he found that fabric-first retrofits had a better carbon performance, even over the whole life of the building.

Azim Jasat of Autodesk highlighted the role of industrialised construction, whose pay-offs include less waste and better tracking of environmental sustainability. Autodesk is developing ‘manufacturing informed design’, a system best suited to design and build contracts by general contractors with in-house fabrication capabilities or a well connected supply chain. Productisation is the key, bridging the gap between design and manufacturing with product templates that can be customised automatically for each project. Behind it is a digital platform connecting Autodesk’s building design and product design portfolio.

Wendy Bishop of Architype talked about its celebrated Entopia Building for the Cambridge Institute for Sustainability Leadership, describing how a target to achieve 70% biomaterials by mass turned out to be impossible. But it did much better by volume, using a plaster product called Diathonite – a cork/lime mix– for the walls’ insulating layer and SonaSpray – recycled paper – to treat hard surfaces for an acoustically acceptable finish.

Anthony Staples of RCKa emphasised the human element in all these strategies, explaining his practice’s ethos of engagement as the key to good sustainable outcomes, as exemplified in its Nourish Hub building in Shepherd’s Bush.

Critical messages

Several messages were loud and clear.

First, making the right choices is massively interdisciplinary – expertise in supply chains, product testing, certification, buildability, building science and engagement is critical.

Second, the application of the cutting-edge strategies described here is still far from mainstream – a problem for net zero.

Third, liability lurks just beneath all this innovation, inhibiting its adoption.

Loudest of all was the question from the audience: how can architects effect change when the decisions, including on budget and timing, are out of their hands?

The answer that came back was to appeal to clients’ ethical sensitivities. Force them to opt out of green solutions and sell them on their long-term benefits.

Meanwhile, the RIBA and its fellow collaborators will keep lobbying to mandate change through regulation.

 

Smart Practice is sponsored by Autodesk

 

 

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