From a presentation by Kelly Roberts at the 2020 Greenbuild Conference & Expo entitled: Modeling Lifetime Carbon: Operations+Embodied+Transportation.

In an action that could have wide global implications a team of experts in the UK has proposed that the upfront and embodied carbon of building materials be compulsorily calculated and capped as a requirement of Building Regulations. US states California, Minnesota and Oregon also have state-level carbon requirements; and the federal government looks like heading the same way.

We recently called these hidden upfront emissions “the elephant in the net zero room”.

Energy performance is regulated under Part L of the UK’s Building Regulations. They are proposing a “Part Z” which would detail the methodology and data requirements.

A statement from the team reads: “Due to the significant contribution that the embodied carbon of buildings makes to the climate emergency, there is a need to introduce legislation towards mandatory reporting of carbon emissions in the built environment, along with limiting embodied carbon emissions on projects.

“If enacted, Part Z would ensure that embodied carbon is assessed on all projects, as part of a comprehensive whole life carbon assessment.

Embodied carbon is often between 20 and 50 per cent of the whole life energy and carbon of a building.

It wants to see carbon emissions capped on all major construction projects – beginning with embodied carbon and proceeding to all carbon emissions.

Forty per cent of emissions – it’s about time for some serious attention

The built environment contributes around 40 per cent of greenhouse gas emissions, and so it’s surprising that only now for the first time, this November’s United Nations climate conference will have a day devoted to the built environment.

The Royal Institution of Chartered Surveyors, the Royal Institute of British Architects, the Institution of Structural Engineers, the Chartered Institution of Building Services Engineers, the UK Green Building Council, and the London Energy Transformation Initiative (LETI) are all bodies whose policies align with Part Z.

The recent UK Climate Change Committee progress report to Parliament also called for mandatory whole-life carbon reporting; in their words: “a plan for phasing in mandatory whole-life reporting followed by minimum whole-life standards for all buildings, roads and infrastructure by 2025”.

Part Z’s authors are sharing the proposal online to obtain industry support. It’s already received support from many quarters of the construction industry including household names.

As occupancy emissions reduce, lifecycle emissions become more significant

One of the authors, Will Arnold, writes: “For a long time, operational carbon has made up the majority of most buildings’ emissions. However, this has changed over the last couple of decades as buildings have become more efficient to operate, along with more of our energy coming from renewables.”

Embodied carbon emissions are already limited in The Netherlands since 2018, and Denmark, Sweden, France and Finland Will follow suit between 2023 and 2027. US states California, Minnesota and Oregon also already have state-level carbon requirements; and the federal government is looking at draft legislation for materials limits on public projects.

Data and tools on embodied carbon exist to back up the proposed work, from:

The UK Green Building Council released a framework definition of net zero carbon buildings in April which includes the embodied carbon of buildings, to help the construction sector to tackle its large environmental impact.

Yet to become mainstream

UN climate champion Nigel Topping says that architects are being slow and “need to act now to ensure that projects coming on stream over the next decade are sufficiently low-carbon”.

They are not jumping on board the net zero bandwagon in great hordes. None of the top fifty global architectural practices are in the UN-sponsored Race to Zero, for example.

“Designers and architects making choices to specify circular, low-carbon and innovative materials on their projects can act as a huge demand signal to industry, product manufacturers and material producers,” Topping told Dezeen.

Much development practice in zero carbon building operates outside the mainstream, and the challenge is to educate the mainstream, including architecture students, about the possibilities.

Timber frame straw bale zero carbon One Planet Development home under construction with an integrated solar roof.

In the UK, zero carbon One Planet Development and Down to Earth homes are typically constructed in what constitutes an emerging new vernacular style using mixed cutting-edge and traditional technologies and materials that combine to be genuinely low impact.

For these buildings, timber frames, often made off-site, are insulated and infilled with either straw, recycled newsprint, or woodfibre batts and boards. They are faced with zero carbon plasterboard substitute, or rendered with clay or lime, and sometimes externally clad with larch.

All of these are materials that sequester atmospheric carbon, making the homes carbon positive.

For roofs they may use recycled steel or reclaimed slate tiles, or have green roofs. They make minimal or no use of concrete, and deploy high performance doors and windows, to achieve almost Passivhaus levels of energy performance at low cost.

These buildings are popular where they exist, low cost, and quick to erect, but significant and well-understood supply chains, while much needed, are yet to manifest.

To develop them will require an upsurge in demand, which itself requires tighter legislation and more carbon-aware procurement from developers, part of the rationale behind Part Z.

“We are ready for embodied carbon regulation, and we hope that the government will engage with industry to introduce Part Z into law,” says Will Arnold.

David Thorpe is the author of Passive Solar Architecture Pocket Reference,  Energy Management in Buildings and  Sustainable Home Refurbishment. He lives in the UK

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