Planting the foundations of sustainable construction
Using plant based materials for building work is nothing new – wood has been used for centuries. What is new is the growing awareness of other plant based options possessing the potential to transform the building sector making it much more sustainable and carbon friendly.
At the moment, the construction industry is neither sustainable nor carbon friendly mainly as a result of the high energy consumption in producing building materials, the actual building process and the ultimate energy requirements of occupants. Change is beginning to happen with examples of plant based building highlighting the long term potential.
An experimental Carbon Neutral house made purely from Cork was built at Eton, Berkshire, winning the RIBA South Award in 2019.
Although there remains a lot of research to be undertaken, plant based construction materials are already available and are being used.
By far the biggest project highlighting the potential of plant based construction materials was seen at the Dutch Design Week, Eindhoven 2021 and is now on view at Floriade 2022. Biobased Creations built a house, of which 98% of the structure was purely plant and bio based. The only exceptions were metal screw fixings and glass windows. The aim as to show just what is possible. As a result, the construction featured 100 biomaterials including wood, seaweed, straw, mushroom mycelium, vegetable fibres and sewage.
All the products are available commercially or are about to be brought to market, providing surfaces both inside and outside the house covering walls, floors and ceilings as well as furnishings. The house itself is a timber frame construction, with a Xylo wood biofinish. This coating is made from fungal cells and chlamydospores which adhere to the wood, forming a self repairing coating which steadily improves in quality over time.
Reed all about it
Other typical product examples include insulation made from reeds, bathroom exterior tiles 3D printed from sewage sludge and algae, tableware made from plants and food waste. Marquetry veneer wall coverings and furnishings which are actually made from corn husks. Totmoxtle was devised by Fernando Laposse, a Mexican designer, and involves corn husks being ironed flat, fixed onto a backing textile then laser cut into interlocking marquetry pieces.
Mogu Floor, specialists in creating bio-based resilient tiles, produced many of the wall and floor tiles used in the house. Their products are made from a mycelium composite core combined with cotton residues, corn husks, rice straw, spent coffee grounds, discarded seaweed and clam shells.
Mycelium roots are proving to be one of the most flexible of all plant based construction materials. Grown.Bio combines mycelium with agricultural waste to make insulation and wall cladding. The two materials are mixed together, placed into a pre-shaped mould then left to grow for five days into a rigid shape. The material is then baked to kill off the mycelium and the resultant product is very strong, tough, CO2 negative and capable of replacing Styrofoam construction products.
Mushroom for improvement
In London, Biohm has developed an insulation panel made purely from mushroom mycelium that outperforms glass fibre, expanded polystyrene and other e-petrochemical/plastic based insulation. An added advantage is the fact that it does not contain resin based synthetic compounds which cause toxic smoke and the resultant rapid spread of flames during fires.
A combination of mushrooms, orange peel, cocoa husks and food waste are being turned into construction and furnishing materials by Biohm, a London based company. Known as Orb, the resultant composite material is 100% biodegradable, vegan and can be moulded into shapes including lampshades.
Over in Cambridge, hemp is being grown and used as a building material. Designed by London based architects, Practice Architecture, The Flat House is an innovative low carbon, two storey three bedroomed house built in just two days, using pre-fabricated hemp based panels. All the hemp was actually grown on the farm.
Margent Farm are now making the hemp fibre based panels available for wider use commenting that, “It is early days in the construction industry but there have been plenty of strong, positive responses. Architects are desperate to move in the right ecological direction and we have seen the recent purchase of hemp building materials for use in a number of bespoke venues. As an external cladding, hemp needs considerable study after Grenfell but we believe natural fibres can play a huge part in the future.”
The panels are created in the form of corrugated sheets which can be used for both exterior and interior wall cladding, replacing materials such as corrugated steel, PVC, bitumen and cement. It is a very durable and strong material, possessing a high cellulose content and is bound with a sugar based resin made entirely from agricultural waste.
One of the biggest advantages of hemp is the fact that it sequesters carbon, locking it in and stopping it being released back into the atmosphere. Another company targeting hemp as a construction material is UK Hempcrete, which has been working with bio based materials for over a decade, in both modern low impact buildings and the upgrading of traditional, historic buildings using a variety of hemp based materials including Hempcrete blocks. Hempcrete director Alex Sparrow has created a definitive guide to the use of cast-on-site Hempcrete (a mix of hemp & lime) in construction.
Demand for such products is expected to increase significantly. 99% of all insulation products on the market are currently fossil fuel generated, a figure which will have to change dramatically in order to meet green targets. Plant based products are expected to take an greater share of products like fibreboard and insulation. Increasingly, companies like Biohm are developing waste management partnerships with industrial partners to transform waste into new construction materials. It is a sector in which research projects feature strongly, with an emphasis on developing new and even more innovative, sustainable materials. Even large companies like flooring giant Forbo now produces a plant based linoleum using linseed, flax and jute. As awareness and demand grows, it will offer new opportunities to farmers and foresters as well as manufacturers and builders, resulting in greater demand for timber, straw, hemp, flax and jute.
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