Evidence-Driven Priorities – The Great Zero Carbon Construction Reset
If you want to cut carbon emissions you need to focus on emitting less carbon. Although that sounds blindingly obvious it’s actually a significant point for the construction sector. It’s one that demands a major change in thinking that targets reductions in both operational and embodied carbon.
And it’s in the area of embodied carbon that policy inconsistencies can become an obstacle.
Construction and the built environment are responsible for nearly 40% of global CO2 emissions. This creates a bigger opportunity to drastically reduce carbon emissions than many people realise.
Yet in the face of a growing climate crisis and increasingly frequent extreme weather events the majority of new buildings in the UK are not capable of zero carbon operational performance. Additionally, current building regulations make it technically infeasible for many construction projects to achieve net zero levels of embodied carbon.
We have to start thinking and acting differently about carbon emissions. This is what we mean by the great zero carbon construction reset.
The first thing we need is urgency. Faced with the very real possibility of catastrophic climate change, why are we still creating buildings that will need energy-efficiency retrofits in the future to achieve net zero operational carbon emissions?
And why isn’t embodied carbon a significant factor in all procurement decisions?
Net Zero Without Compromise
The first step is to address what net zero really means, both in terms of operational and embodied carbon. The commonly accepted standard for net zero carbon in operation is defined by Net Zero Carbon Buildings: A Framework Definition UK Green Building Council (UK GBC). This is a far more useful benchmark than EPC ratings.
The UK GBC framework calls for whole life carbon assessments to be undertaken and disclosed for all construction projects. This level of transparency should help to drive carbon reductions. In the UK, only the education sector seems to have embraced this requirement.
Significantly, the framework states that, ‘The embodied carbon impacts from the product and construction stages should be measured and offset at practical completion’.
This means accounting properly for embodied carbon and treating compromises such as offsetting as the last resort. We can’t continue to use ‘emit and mitigate’ as a crutch. Project specifications and procurement processes must consider whole-life carbon if we are to achieve the level of impact needed. Specifying a building that is net zero carbon in operation is only part of the story.
Choices made about fabric and construction methods can create a huge debt of embodied carbon emissions that can never be repaid. The best way to avoid this is with a high structural timber content. This is because atmospheric carbon is extracted by growing trees and locked into the timber.
In theory you could ‘pay back’ embodied carbon by over-specifying onsite renewable energy generation to make the building operationally net carbon negative. But that won’t get those embodied carbon emissions back.
Change the Thinking
We all understand why there are restrictions on the use of combustible construction materials in the UK. Safety and preservation of life must always come first. But building standards should also be based on evidence and verifiable test data.
Structural timber has a net negative value for embodied carbon. Increasing the structural timber content using SIPs and Glulam balances out the embodied carbon in steel, cement and other traditional construction materials.
With currently available technology and materials we can’t really talk about net zero carbon construction without using significant quantities of structural timber. But for buildings over 18m in height structural timber is currently ruled out.
Elsewhere in the world there’s a different perspective. In Norway you can find the 85.5m high Mjøstårnet – the tallest timber structure in the world. In Paris, any buildings created for the 2024 Olympics below eight storeys must be made entirely from wood. And the USA is shortly expected to allow timber structures up to 18 storeys.
Whole Life Carbon
When Innovaré and our partners talk about net zero carbon we are talking about the entire building life cycle. We don’t just model operational carbon, we look at the whole process: materials, construction methods, operation and maintenance, and end-of-life.
Our detailed modelling and real world project data show that truly net zero carbon construction is both feasible and deliverable using existing construction technology.
If we collectively reset the debate we can be sure we all mean the same thing when we talk about net zero carbon construction. More importantly, we can start making a meaningful difference to the carbon footprint of the industry and tomorrow’s built environment.
But to make the biggest impact we also need to address the role of products such as SIPs that meet rigorous fire safety standards yet are still banned in many new buildings.