Is It Time To Take The Politics Out Of Net Zero Construction?

Sometimes it’s the questions that nobody wants to ask that hold up progress. In the case of net zero carbon construction in the UK, the question is about the role of structural timber.

Full carbon accounting for a new building has to take the whole lifecycle into consideration. A building can be carbon neutral in the operational phase if it’s airtight, well insulated and powered by renewables.

But this avoids the issue of all the carbon emissions produced when raw materials were extracted, processed and transported. It also ignores the carbon emissions from the construction process – and those from demolition and waste processing at the end of life.

Material Choices Matter

Steel, concrete and blockwork have high levels of embodied carbon. Producers are working hard to reduce these levels but they can’t eliminate them. The cement industry’s carbon reduction plan assigns over one third of the future contribution to net zero to carbon capture technology. This doesn’t yet exist at scale. 20% is expected to come from smarter building design that reduces the typical cement content of a new building.

These materials will not get us to true net zero measured over an entire building lifecycle. Structural timber can! It’s one carbon capture technology that we know works.

Structural timber has sequestered carbon locked into the material as trees grow. The negative figure for embodied carbon in structural timber is needed to balance the positive contribution from other processed construction materials.

This reality is hard to avoid.

Building Regulations and Obstacles to Change

We all understand why there’s a ban on using flammable materials on buildings over 18m in the UK. But this is a blunt instrument being used to solve a more nuanced problem. If we could take the politics out of the discussion and focus on the science, we have a chance of achieving net zero carbon construction. Without far greater use of structural timber we might get 60% of the way there, but no more.

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 expected to allow timber structures up to 18 storeys from later this year.

Building systems such as i-SIP and i-FAST are fully tested and certified for fire safety. In a fire, structural timber will char on the surface while maintaining its structural integrity. Also, it doesn’t give off toxic fumes.

We understand why these issues are sensitive ones. But if net zero carbon construction is really the objective, it’s a nettle the nation needs to grasp.

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