Why straw could be the next big thing in sustainable construction

Posted by Derek Mason

15th February 2022

Picture credit: James Wainscoat on Unsplash

How often do you think about using an ancient material in your projects? I tend to stick to the more traditional materials of the 20th and 21st centuries but, when you’re looking at sustainability, there’s a logic to digging into substances from the past.

With that in mind, The University of Plymouth has started work on the first building in the UK to be made from a modern-day version of cob. As you may already know, cob is a natural building material made from subsoil (the soil beneath the topsoil), water and fibrous organic material – usually straw.

Once this single-storey structure is complete, it will be used as a classroom and laboratory, as well as a ‘demo’ building to show to the building designers of the future.

The CobBauge project makes use of a scientifically upgraded version of cob. Researchers looked at a variety of different soil and fibre mixes to come up with a double-layered composite wall that’s denser and also lighter in weight than the ancient version. This combines strength and insulating properties that meet thermal regulations here and in France.

It sounds like it’s a substance that could be utilised in energy-efficient housing, and researchers will be able to better understand its performance by monitoring the university building. Sensors will measure energy use as well as indoor air quality.

The project is being led by the Sustainable Earth Institute at Plymouth University, alongside multiple partners, including Earth Building UK and Ireland (EBUKI), Hudson Architects, Ecole Supérieure d’ingénieurs des Travaux de la Construction (ESITC), Parc naturel régional des Marais du Contentin et du Bessin (PnrMCB) and Université de Caen.

It’s essentially a 45 m2 living laboratory that will help students and construction professionals to understand how this material performs. The walls are already in place, and building work is expected to finish in spring 2022.

These kinds of projects are not new, but they’re getting more attention these days because of the bigger push for us all to look at building sustainably – a push that has come about partly because of a wider awareness of the challenges our planet is facing.

In any building project you want to find the right materials for the right situations, and these researchers will have looked very carefully at properties such as the diameter of the straw and the straw’s fibres, which can be fractions of a mm.

Building with organic matter and other alternative materials is an area that needs more investigation if we’re to build more sustainably. I’m looking forward to hearing about more and more of these experiments. And it’ll be interesting to see whether any of these alternative building methods re-enter the mainstream.

In the meantime, if you need assistance with the structural elements of an upcoming project, please do get in touch.

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