Algae bricks and oyster shell walls: what's on the horizon for eco-friendly building in Australia?

The Guardian

14-06-2025

The average person might simply see green goop, but when Ben Hankamer looks at microalgae, he sees the building blocks of the future.
Prof Hankamer, from the Institute of Molecular Bioscience at the University of Queensland, is one of a growing number of people around the world exploring ways living organisms and their products can be integrated into our built environment – from algae-based bricks to straw or fungi wall panels, and render made from oyster shells.
'Biomaterials', broadly speaking, are materials made using biological matter, and a small group of engineers and designers are turning to them for their 'visual richness', alongside their eco-credentials.
With traditional construction materials such as cement and steel coming under scrutiny for their environmental impact, architects and designers working to develop biomaterials say one benefit is the biological 'ingredients' capture CO2 as they're grown. Once the ingredient (microalgae or seaweed, for example) is harvested and made into a building material, it's often 'dead' and now acts as carbon storage. But materials are also being designed so the organism continues to live – or has other organisms then living on it – meaning it continues sucking up CO2 and emitting oxygen over its lifespan.
So what are the new biomaterials sprouting up, and how long until you might see them on the market?
In the US, Prometheus Materials is already using microalgae to create a cement replacement for construction blocks, while macroalgae – or seaweed – is being used for housing in Mexico. Danish company Søuld is producing acoustic panels from eelgrass, inspired by a roof thatching technique used on Læsø island dating back to the 1600s.
In Australia, Hankamer's team runs a facility testing green algae production systems. Some of their microalgae has gone to Müge Belek Fialho Teixeira, an associate professor at Queensland University of Technology whose team has used it to create breeze blocks called RoboBlox.
The blocks are 3D printed, allowing for bespoke designs. Prototypes displayed at an international construction exhibition in 2024 looked like a more delicate, organic-shaped, terracotta-coloured version of the decorative mid-century Besser blocks that line many a suburban street.
Using 3D printing means the blocks are slower to make than traditional mass-produced breeze blocks that all use the same mould. Teixeira says this has so far deterred potential investors they've spoken with, and the blocks are on pause until they can secure a partnership. They also need to do an economic analysis to compare the cost of production with existing products.
At the University of Technology Sydney, Dr Kate Scardifield and colleagues have taken seaweed from an industrial cultivation plant and combined it with oyster shells from the NSW coast food industry to create a mottled seaweed-green concrete-like brick.
They're testing a range of seaweed waste products, from sheeting and cladding to interior tiles and acoustic panelling, at various scales to ensure they meet industry standards. There are multiple stages new technologies must pass to move from the lab to commercialisation; Scardifield says they're working with industry partners to progress these products but can't speculate how long they will take.
One algae product already in use is a decorative film developed by Other Matter. The organic, marbled material has recently been used in skincare brand Aēsop's new store in Hainan, China, where sheets of the decorative algae-film (sent rolled in a poster tube) were applied over backlit glass on the walls and pillars.
'We've been able to create wonderfully deep fluid patterning reminiscent of marble but without the heavy environmental cost or logistical limitations of quarried stone,' director of Other Matter Jessie French says. The sheets can also be melted down for reuse.
Using oyster shells donated by restaurants and seafood wholesalers, Australian company Mineral Fox has developed a range of renders for interior walls in various textures, ranging from natural pinks and browns to off-whites and pale khaki, with flecks of opalescent oyster shells performing something of a terrazzo effect in some finishes.
Founder Karmin Kenny says the render has been used in the Brisbane office of global architectural firm Arup, and is due for use in some large commercial and residential projects in Sydney, including one in line to be the largest-scale use of recycled oyster shell render in the world.
Prices begin at about $180/sqm, including the cost of materials and labour for installation, going up to $400/sqm for complex architectural finishes. This puts it very much in the realm of premium products: HiPages suggests the average range of traditional rendering (made of cement, sand, water and lime) is between $30 and $150/sqm in Australia.
Sign up for Guardian Australia's breaking news email
In the UK, University College London's Brenda Parker and collaborator Marcos Cruzan architect and professor of innovative environments say the next frontier is 'engineered living materials', where the biological matter continues to live beyond installation and respond to its environment – or the material may simply be designed to attract living things. For example, their Poikilohydric Living Walls, now installed in a house in Scotland and a primary school in south London as study sites, are designed to be colonised by algae, moss and lichen. The plants can remain dormant for long periods of time and then revitalise when there's rainfall – meaning they don't need irrigation systems.
'Rather than creating completely new materials, we've worked with the most available material on Earth – concrete – and looked at different ways of doing carbon offsets,' says Cruz.
Prantar Tamuli, a pastdoctoral student of Parker and Cruz, also developed wall panels made of a semi-translucent material embedded with living cyanobacteria. As the bacteria is still alive, it continues to photosynthesise, drawing in carbon dioxide and producing calcium carbonate, which strengthens the panels. Prototypes have been installed at St Andrews Botanic Garden in Scotland.
Parker, an associate professor of sustainable bioprocess design, says the evolving and individual looks of living biomaterials is part of their beauty – and the benefits go beyond capturing carbon.
'There's a reason we enjoy spending time in nature, we know it has benefits for us.' Biomaterials, she says, puts the built environment on a 'continuum with nature'.
Fungi, meanwhile, has gained popularity as a leather alternative, but it's also drawing increasing interest for use in building materials.
Co-founder of the Bio-Based Materials Design Lab at the University of Western Australia, associate professor Rosangela Tenorio has created building panels using bamboo and mycelium, the root-like fibres that grow from fungi.
The mycelium isn't alive in the panels, which allays concerns about potential negative health effects, and they can be used externally when waterproofed with existing natural coatings.
But they've so far struggled to attract Australian funding, outside the university's support, to build at a large-enough scale for testing, which is why Tenorio will soon travel to Timor-Leste to build a prototype building with the panels.
Back in Australia, straw – a traditional building material on other continents – is slowly finding a market.
Director of Viva Homes Sam Vivers says they've built 70 straw-bale houses and a further 41 using straw panels. There are different finish options for the prefabricated panels, including lime render or plywood cladding. The rendered panels have also been tested for fire resistance by CSIRO and are allowed for builds in areas classified as extreme bushfire risk.
'As a relatively new and unconventional product in Australia they don't fall within the National Construction Code, so we provide a 'performance solution' for each build which satisfies the building regulations,' Vivers says.
Another Australian company, Durra Panel, makes non-structural wall and ceiling panels from reclaimed wheat straw, including a range incorporating biochar. Despite being used in thousands of projects – from homes to sports stadiums, recording studios, and even the media centre at the 2000 Sydney Olympics – general manager Ainslee Haslemore says their product is 'still relatively unknown' to many in the construction industry and among consumers.
Irma Del Valle Nachon of sustainable architecture firm Breathe says 'many biomaterials inherently carry a distinctive organic aesthetic'. 'We see this as an opportunity for both clients and designers to embrace the unique, honest visual and tactile qualities these materials offer.' The firm recently used the hemp-based panel HexCore for a benchtop in a circular studio fitout, but there are challenges to using biomaterials, she says.
'We've encountered significant barriers to specifying them in projects, ranging from limited availability, long lead times, higher costs – compared to more readily available 'business as usual' construction materials – and the lack of certification needed to meet Australian standards and the building code.'
QUT professor Tim Schork, a member of the international Building with Blue Biomass network, says building regulations were written for conventional materials, but many biomaterials require different use and maintenance – making testing and certification difficult.
In contrast Paul Nicholas, who leads the network and is an associate professor at the Royal Danish Academy School of Architecture, says the Danish government has been reviewing regulations to create faster pathways for biomaterials. Danish architectural firms are more open to using experimental products, he says, and Denmark even has a 'mini-Bunnings' purely for bio-based building materials.
Schork is hopeful Australia can have similar support from the larger building industry to support real change here too.
Lydia Hales was one of two journalists in the Science Journalists Association of Australia's science journalist in residence program, funded by the Copyright Agency's Cultural Fund. The 2025 program was based at the University of Queensland's Institute for Molecular Bioscience.