In a world where concrete is as ubiquitous as air, its environmental toll is impossible to ignore. The production of cement, the binding agent in concrete, accounts for about 8% of global carbon dioxide emissions. Steel reinforcement, often added to compensate for concrete’s weakness under tension, only adds to the problem. But what if there were a way to build sturdy floors using far less of these materials — without sacrificing strength or affordability?

Lotte Scheder-Bieschin, a PhD student at ETH Zurich, may be on to something. She has developed an ingenious formwork system that could transform the way we construct buildings. Her invention, called Unfold Form, is a lightweight, reusable mold that slashes concrete use by up to 60% and steel reinforcement by a staggering 90%. If applicable at scale, it could become a blueprint for a more sustainable future in construction works.

Strength Through Geometry

Scheder-Bieschin’s system relies on a simple yet powerful principle: strength through geometry. Instead of relying on thick slabs of concrete reinforced with steel, her design uses vaulted floors with intricate rib patterns. These patterns, inspired by the natural curves of seashells, distribute weight efficiently, allowing for thinner, lighter structures that require far less material.

The key lies in the formwork itself. Traditional molds for non-standard concrete shapes are often bulky, single-use, and made from petroleum-based materials like Styrofoam. “Unfortunately, this cancels out some of the sustainability gains,” Scheder-Bieschin explains. Her solution? A foldable, reusable formwork made from thin plywood strips connected by textile hinges.

The system is as elegant as it is practical. Four compact units, each weighing just 24 kilograms, can be unfolded like a fan and assembled into a sturdy mold. Once the concrete is poured and cured, the formwork can be detached, folded, and stored for future use. “I wanted to ensure my design was simple enough for anyone to build, regardless of their circumstances,” says Scheder-Bieschin, who demonstrated this by assembling the formwork herself during her pregnancy.

A Solution for a Global Problem

One of the most striking aspects of Unfold Form is its accessibility. It doesn’t require specialized knowledge or expensive equipment. “The only things needed in addition to the materials are a template for the shape and a stapler,” Scheder-Bieschin notes. The materials for her prototype cost just 650 Swiss francs ($USD 715) — a fraction of the cost of traditional formwork.

This simplicity makes the system ideal for regions with limited resources, where the need for affordable, sustainable housing is most acute. To prove its versatility, Scheder-Bieschin and her team tested the formwork in South Africa, collaborating with a local firm called nonCrete. Using bio-concrete made from shredded invasive vegetation, they successfully cast a second prototype in Cape Town.

“The goal is to use this innovative formwork system to construct high-quality, dignified, and sustainable housing in South African townships,” Scheder-Bieschin says. Her team is now planning training programs to teach locals how to build with the system, empowering communities to construct their own homes.

From Paper Models to Real-World Impact

The journey to Unfold Form began with paper models on Scheder-Bieschin’s desk. Drawing on her expertise in bending-active structures, she experimented with curved-crease folding — a technique inspired by origami. By gluing pieces together in new ways, she eventually devised a system that starts as a compact stack and unfolds into a sturdy mold.

The transition from paper to plywood was no small feat. Scheder-Bieschin solved the challenge by using textile hinges, which allow the plywood strips to bend and lock into place. The result is a formwork system that is not only lightweight and reusable but also remarkably strong.

As Scheder-Bieschin prepares to complete her doctorate, her sights are set on the future. She plans to continue developing the system as a postdoc at ETH Zurich, with the goal of bringing it to market. Her next project? A market hall in a Cape Town township, built using her innovative formwork.