As the construction industry accepts its role in tackling the climate emergency, it is clear that we cannot continue as we do today. It is essential that we take into account not only how we use our buildings, but what we put in them in the first place.
Just as our dietary preferences shift away from carbon-intensive meat and dairy products, carbon-intensive building materials such as steel and concrete must be replaced with ‘healthier’ plant-based alternatives. low carbon content. Basically, the construction industry cannot decarbonize without adopting its own vegan diet.
So what are these “vegan”, or bio-based, to use a more established industry term?
Bio-based materials are simply materials that grow or are a natural part of the biosphere – think wood, straw, hemp, cork, clay, and soil. These generally have less carbon incorporated. Wood contains about three times less embedded carbon than steel and more than five times less than concrete. These materials also sequester carbon, which means that as they grow they absorb and store carbon, attaching it to the material for the life of its use.
And this is where architects, engineers and designers can really make a difference – by innovating and incorporating these materials into our buildings.
Wood is undoubtedly the key material to adopt if we want to reduce the carbon impact of our buildings. Its applications go beyond cladding and half-timbering as current business does today. Its structural capabilities are extensive, producing taller and taller buildings on par with concrete and steel, and is the only current viable structural alternative to them.
Engineered timber such as cross-laminated timber (CLT) and glued-laminated timber offer significantly increased applications, enabling solid and hybrid timber structures, seamless superstructures, and rapid prefabrication and construction of entire frame systems. . It can even be used as insulation to retrofit our existing buildings, which is necessary for a more sustainable use of materials – because currently 99% of all insulation on the market is generated by fossil fuels.
Beyond wood, materials such as cork, hemp, and straw are very insulating and lightweight, and like wood, can be used in a variety of applications.
Cork can be used as a floor covering, rigid insulation, exterior cladding or even as a kitchen countertop. Hemp can be used as incredibly tough exterior cladding panels and roofing tiles, used for its insulating properties as insulation boards and fiberboards, or the better of both as thermally performing hemp building blocks.
The insulating properties of straw allow it to be used as a fill insulation and, more recently, in prefabricated exterior wall systems.
A cork block house was even nominated for the Stirling Prize in 2019, demonstrating that these materials can create world-class buildings.
But why are bio-based materials still underused? One of the reasons is their ignorance of the construction industry, regulators and insurers who have been used to steel, brick and concrete for so long. The regulatory landscape still favors proven carbon-intensive materials, making the use of bio-based materials more complex and costly. This prevents a demand for these materials and in turn discourages innovation and use.
However, this regulatory landscape is starting to change. The French government has established legislation requiring that all new public buildings be constructed from at least 50% biobased materials from 2024. In Europe and North America, the capabilities of engineered wood are recognized, and we see more and more tall wooden skyscrapers. built.
The materials are there, with capabilities to replace our carbon-intensive “meat and dairy” materials with low-carbon “vegan” alternatives without overriding performance and improving our pallets as designers. By seeking to innovate and integrate these materials into our practice, architecture can play a key role in decarbonizing the construction industry.
Dan Stokes is a senior architectural technologist at HLM Architects