The need for an honest approach to net zero

An opinion piece by Simon Corbey, ASBP Director for Futurebuild

Much like Greta, I am finding the obsession with net zero as a target incredibly frustrating. We now have high impact industries like concrete and steel publishing their route maps to net zero. Indeed, SteelZero launched in December 2020 with the top takeaway being It won’t be easy – but it’s definitely possible. This lulls the construction communities into a false sense of security, that somehow rapid decarbonisation will just happen over time and so we can continue with business as usual.

Efforts to reduce carbon emissions by the major contributors to climate change are of course encouraged and there are some new innovations, but how realistic are these? For example, the concrete industry is hoping that by replacing steel reinforcement with graphene and using 3D printing, this will reduce carbon emissions by 50%. A positive news story for sure, but is it just that, a good story? This is going to be trialled on HS2 in Spring 2022 but at what scale is unclear. It would be great if this solution was a magic bullet but as we know, magic is sleight of hand and I fear this is what we might have here.

After all, we have been reading about low carbon concrete and carbon capture and storage since the 1990s, but the technologies still remain frustratingly out of reach at any scale. Despite these new innovations the embodied impact of the concrete will still be significant and it’s highly likely that there is not enough GGBS (ground granulated blast-furnace slag, a by-product of steel production) to enable significant quantities of low carbon concrete.

So, what do we mean by net zero? Commonly, net zero is focussed solely on operational emissions. But hang on a minute, what about the rest of the pie? An increasing number of construction professionals are demanding that the target we all should be adopting is net zero whole life carbon!

Currently around 50% of whole life carbon emissions from new construction can be contributed to the building materials, the construction process, maintenance and disposal at end of life – known as embodied carbon emissions. These emissions currently fall largely outside the scope of current regulation, although we do hope and expect regulations to be introduced over the coming years. Indeed, ASBP, ACAN, LETI and many other organisations have been lobbying for this to happen, with the latest example being Part Z, a proposed amendment to UK Building Regulations

The UK is required to achieve net zero by 2050 in line with the Climate Change Act. The built environment is therefore making efforts to decarbonise the delivery of buildings and infrastructure across all professions and disciplines. Inconsistencies remain with respect to net zero definitions, although we welcome the work of LETI and the Whole Life Carbon Network (WLCN) in seeking to agree on a common set of definitions for the buildings and infrastructure sectors. The document defines ‘Net Zero Whole Life Carbon’ as:

“Where the sum total of all asset related GHG emissions, both operational and embodied, over an asset’s life cycle (Modules A1-A5, B1-B7 (plus B8 and B9 for Infrastructure only), C1-C4) are minimized, meet local carbon, energy and water targets, and with residual ‘offsets’, equals zero.”

As shown in the life cycle assessment diagram above, embodied carbon covers the emissions that arise from the energy and industrial processes used in the processing, manufacture and transportation of the materials, products and components required to construct, maintain and refurbish a building. It also includes deconstruction, disposal and end of life aspects. The greenhouse gas emissions arising from the material production, extraction and construction phases up to a building’s completion are known as ‘upfront embodied carbon’. These emissions have already been released into or sequestered from the atmosphere before the building is occupied.

The relative significance of embodied carbon, both ‘upfront’ and ‘whole-life’, is likely to increase as the UK grid decarbonises and operational carbon emissions reduce. At the same time, if the number of new homes built every year increases to 300,000 as the Government has pledged, there will be an absolute increase in embodied carbon emissions from rising material supply and the requisite construction activity.

Embodied carbon emissions are “locked in” when the building is built – they can never be reduced, and their impact will be felt for the life of the building. Embodied carbon savings made during the design and construction stage are delivered NOW. If we are to meet the world’s climate goals and limit global warming to well below 2C, we must concentrate on reducing emissions immediately, rather than in 10-30 years or at the end of a building’s lifecycle.

There are encouraging examples internationally, particularly by the Nordic countries who are working towards regional carbon neutrality ahead of the UK and European Union’s goals.

Finland is aiming at carbon neutrality by 2035 and is developing a set of progressive policies, including new legislation for low-carbon construction. This includes setting normative carbon limits for different building types before 2025 and creating a generic emissions database. The database will cover all main types of products and materials, sources of energy, modes of transportation as well as other main processes such as site operations and waste management. They have also created the concept of a carbon footprint for the whole life emissions and a carbon handprint to include climate positive outcomes such as the long-term storage of biogenic carbon in wood-based products, based on EN 16485.

We look forward to hearing from Matti Kuittinen, Senior Specialist at Finland’s Ministry of the Environment at our natureplus hosted symposium on October 12thCarbon Capture and Storage for Free. We’ll also hear about the French approach, which uses dynamic LCA, whilst renowned climatologist Hans Joachim Schellnhuber, founding director of the Potsdam Institute for Climate Impact Research has been invited as a keynote speaker.

As we pass the halfway mark in what is another vital year of climate action, and the UK’s hosting of COP26 in Glasgow draws ever closer, it is clear that there is much to learn from our peers and colleagues in Europe and further afield. Introducing regulation of embodied carbon would have a dramatic effect on the emissions of the UK construction sector. Will the Government step up to the plate?

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