Greener composites for greener buildings

Monday, 13 July, 2015
Weather cladding and external wall panels made of flax, jute, and a resin from sugar cane waste? Yes indeed, if you want a durable, low-carbon solution… EU-funded researchers have developed innovative biocomposites based on such materials and demonstrated their potential in construction.

BioBuild stand at EcoBuild exhibition showing the External Wall Panel (EWP) front centre.  Made from flax fibre in a polyester resin matrix. © NetComposites

“The aim of the BioBuild project was to reduce the amount of energy needed to produce construction elements — the so-called embodied energy,” says Anthony Stevenson of Netcomposites in the UK, the project coordinator. The partners’ research focused on composite materials mainly derived from biological materials.

Biocomposites are fibre-reinforced polymers, i.e. plastics strengthened with woven or non-woven textile materials, where at least one of the components is made from agricultural products.

Biobuild selected biocomposites that show promise as building materials and improved key characteristics such fire retardance, moisture resistance, and the bonding between the fibres and the plastic. The partners then used these substances to produce and test various types of building component.

These applications included external wall panels and cladding, and an internal partition system. In the case of the cladding, the embodied energy is nearly halved compared to a reference product, whereas the other two offer savings of 10 to 15%, says Stevenson. A fourth test application — lamellae for suspended ceilings — also offered a number of advantages, he notes, although the embodied energy was not actually reduced.

Pick your materials

“Back in the 1970s, the amount of energy a building would need for heating and lighting throughout its lifetime was about 10 to 20 times that expended in producing the materials and constructing it in the first place,” Stevenson explains.

Today, this ratio has changed. Innovation in areas such as heating, insulation and lighting technology is helping to minimise the energy consumption of modern buildings.

However, there is still ample room for improvement in the construction phase. “If you want to reduce greenhouse gas emissions from housing, you also need to look at the energy used and the amount of carbon dioxide emitted in the process of making the materials,” Stevenson notes.

BioBuild set itself the task of developing biocomposites into construction elements that require less energy to produce than similar components made of steel, aluminium or concrete. The project’s biocomposites are made of flax or jute fibres, combined with plastics derived entirely from sugar cane waste or partly from vegetable oils.

To improve the sustainability and performance of their biocomposites, the BioBuild partners introduced a number of advances. Stevenson reports that the partners have developed treatments and coatings to make the fibres fire retardant and moisture resistant and improve their adhesion to the plastic. The project also identified promising areas for further development work.

Reap the rewards

Among the applications BioBuild developed before the project ended in May 2015, the wall panels have met with particular success. Durable, self-supporting and comparatively light, these moulded elements can be produced to a wide variety of designs, giving architects great freedom to shape elements that meet exacting technical and aesthetic requirements.

The partners’ prototype is a facetted façade element including a window that is not entirely vertical — the frame is slightly tilted to provide a degree of self-shading. This feature reduces the burden on air conditioning systems and further boosts the panels’ environmental performance. This innovative concept won the project an award from JEC, a leading composites industry organisation.

High Performance, Economical and Sustainable Biocomposite Building Materials
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