In the summer of 2014, in the inner courtyard of MoMA PS1 in Long Island City, a tower roughly twelve metres tall rose up, made from thousands of white, porous bricks as light as polystyrene, arranged into three hollow bulbs connected at the base. By the end of September, the tower had been taken apart piece by piece and the bricks — every single one — became compost, distributed to community gardens in the surrounding neighbourhoods. This didn't happen because the project had been conceived as temporary in the conventional sense (many pavilions are): it happened because the material itself, at the end of its cycle, literally returns to being earth. The project was called Hy-Fi, by the New York studio The Living, founded and led by architect David Benjamin, that year's winner of MoMA's Young Architects Program.
How you grow a brick
The material behind Hy-Fi is produced by Ecovative Design, a company founded in 2007 in New York State by Eben Bayer and Gavin McIntyre, two mechanical engineering students at Rensselaer Polytechnic Institute who had been looking for a biodegradable alternative to expanded polystyrene packaging. The process starts from a low-cost agricultural waste product — in Hy-Fi's case, chopped corn stalks, a residue of the food supply chain that would otherwise be burned or buried. This substrate is inoculated with fungal spores (a strain selected for growth speed and for the mechanical properties of the final result) and poured into a mould, in this case moulds shaped as standard-size hollow bricks.
Over roughly five days at controlled temperature and humidity, the mycelium — the network of microscopic filaments, hyphae, through which the fungus explores and digests the substrate — colonises the entire mass of corn stalks, binding them together into a continuous solid block that faithfully replicates the mould's shape. At this point, the block is removed and dried or given a brief heat treatment: a crucial step, because it kills the organism and stops growth exactly where it's wanted. Without this step, the fungus would keep growing, eventually producing fruiting bodies (the visible mushrooms) and progressively degrading its own structural substrate — the exact opposite of what's needed in a building material, where dimensional stability over time is a basic requirement.
Hy-Fi's structure: what the engineers had to solve
On its own, mycelium brick has very low compressive strength — on the order of 0.1-1.2 N/mm², against the 20-30 N/mm² of an ordinary fired brick. Building a twelve-metre tower with a material like this required completely rethinking the structural logic: it wasn't a matter of swapping one material for another within the same construction scheme, but of designing a geometry able to work with those specific mechanical properties. The Living solved the problem with a form of bulbs tapering upward — wider at the base, where the compressive load is greatest and the resisting section widest, narrower at the top — and with a light auxiliary structure (vertical uprights) that stiffens the whole without introducing heavy materials, or ones incompatible with the project's compostable end of life.
At the top of the tower, a reflective film surface channels sunlight downward, lighting up the structure's hollow interior and creating an optical effect that made Hy-Fi one of the most photographed installations of that year's PS1 programme. It's a detail worth noting: the project's most "engineered" component — the reflective cladding — was not as biodegradable as the bricks, and it was in fact removed and disposed of separately at dismantling, while only the bricks ended up as compost. It's a distinction any honest life-cycle assessment of these projects has to make: not everything in a "biodegradable" pavilion truly is, to the same degree.
Why it isn't (yet) a structural material
The most immediate limit of mycelium as a building material remains its mechanical strength, which rules it out of any primary structural use in the traditional sense of the term. The second limit is sensitivity to moisture: the material, being in effect a dried organic biomass, reabsorbs moisture if exposed to prolonged environmental conditions without protection, with a risk of softening and residual biological activity resuming if not treated correctly. For this reason, Ecovative's current commercial uses focus on lower-risk applications: protective packaging (the company's original market, now directly replacing polystyrene for major clients such as Dell and IKEA in some products), non-structural acoustic and thermal-insulation panels for interiors, and a specific product called MycoBoard, conceived as an alternative to particleboard for furniture and fittings, with the advantage of not requiring the formaldehyde resins typical of that sector.
Ongoing research — both at Ecovative and in several university labs, from MIT to London's Bartlett School of Architecture — aims to improve mechanical properties by varying the substrate (longer, stronger fibres in place of chopped corn stalks), the fungal strain used, and the growth density achieved by compressing the material during or after colonisation. None of these developments have yet, as of 2026, produced a mycelium composite usable in a load-bearing structural element certified to a Eurocode: the path remains non-structural uses, where the environmental advantage — very low process energy compared with any conventional insulation material, waste raw material, complete end-of-life biodegradability — is already a solid fact today, not a promise.
A legacy that goes beyond the single pavilion
Hy-Fi wasn't the first experiment with mycelium in architecture — Ecovative had already been experimenting for years with smaller installations, and other research groups were working in parallel — but it was probably the project that made the material visible to a broad audience, not just specialists, demonstrating at real scale (not lab scale) that a self-supporting structure of significant size could be built and taken apart according to a fully circular-economy logic. The fact that, ten years on, mycelium features consistently in conversations about the building materials of the future — alongside materials with a much longer research history, like self-healing concrete — owes a good deal to the visibility of that single New York summer.