A team at Chalmers University of Technology, Sweden, has worked out how to turn baker's yeast into an architectural surface.
The study, published in Frontiers of Architectural Research by Yagmur Bektas, Malgorzata Zboinska and colleagues at Chalmers and Aalto University, focuses on a 3D-printable biomaterial made almost entirely from regenerative materials. The optimised recipe is precise – three per cent deactivated yeast, thirteen per cent micro-fibrillated cellulose solution, one per cent sodium alginate from brown seaweed, five per cent glycerol, the rest water.
The cellulose fibres give tensile strength and hold the printed shape. The alginate gives stability as the piece dries, while glycerol stops it cracking. The formula starts as a paste and is extruded at room temperature from a robotic arm, layer on layer, then dries into a flat translucent sheet without a kiln, a curing oven or a gram of plastic.
The material could be used for screens, room partitions or decorative wall panels – the interior elements usually moulded from plaster, plastic or synthetic textiles. The team assembled seventeen printed tiles into a standing screen to show what the material can do at the scale of a room.
While it embraces the novelty of new ingredients, the yeast earns its place on the merits the researchers set out. It doubles roughly every ninety minutes, grows on the sugar-rich leftovers of brewing and papermaking, tolerates contamination, and – because it is single-celled – produces a more uniform and predictable material than mycelium. Mycelium, the fungal network that has dominated bio-based building potential moulds easily, varies batch to batch, grows slowly, and cannot be printed directly.
There are elegant mechanisms and craft behind the research. The yeast does two opposite jobs depending on how it’s treated before mixing. Left intact, the deactivated cells behave as a filler, giving the material bulk and rigidity. Or if ruptured, the homogenised cells burst and release their proteins, carbohydrates and lipids into the mix, which makes the same yeast a binder.
The authors also highlight that the work challenges the idea that a material must last as long as physically possible. The research asks designers to think in terms of shorter life cycles and treat the ageing or degradation of a material as part of the design. The material is meant to biodegrade, and this isn’t seen as a limitation.
Architecture’s instinct is often based on permanence. Durability is one of the field’s few uncontested virtues, and for good reason: the most sustainable building is usually the one that already exists and is kept. Designing a material to break down on a schedule only makes sense once the question is narrowed to the right category of object. A daylight screen is not a footing. A decorative partition is not a load-bearing wall. These are the elements of a building that already get torn out and replaced on tenancy cycles. And the conventional versions, such as synthetic panels and plastic screens, are made from non-renewable, toxic, forever materials, designed to last for centuries and then sit in landfill for centuries more, breaking down into microplastics on the way.
Construction accounts for roughly a third of global raw material depletion and a third of solid waste. A material whose physical life is matched to its actual useful life, rather than wildly exceeding it, is answering a genuine mismatch when it comes to design.
There are trade-offs, however. The strongest tiles reached an average tensile strength of 2.7 megapascals and stretched roughly a quarter of their length before breaking – in line with comparable bio-based films, and roughly the strength of a fruit leather. Other areas of additional research are how it will respond to indoor swings in heat and humidity, fire resistance, and acoustic and thermal performance. The one tentatively encouraging result came from the heat tests, where the yeast and glycerol kept the material from decomposing completely above 330°C in the way pure cellulose does.
As a material with potential, it demonstrates a principle: that the parts of a building with short useful lives could be made from biomass that returns to the soil, and that a material’s eventual breakdown can be designed for rather than engineered away.
