Wood and cement alternatives to reduce the ecological footprint

The built environment is a climate nightmare. Producing concrete, steel, and plastic—the materials we commonly use to build our infrastructure—emits huge amounts of carbon dioxide. If concrete were a country, it would be the world's fourth-largest emitter of greenhouse gases after China, the United States, and India. For this reason, reducing the carbon footprint of building materials is an essential effort to protect the climate. Among the solutions considered so far, the simplest and most effective is replacing concrete with wood. Buildings such as the Ascent Tower in Wisconsin, the Mjøstårnet in Norway, and the HoHo tower in Vienna have successfully demonstrated the potential of wood construction as an alternative to concrete and steel. Now, two buildings are being constructed in Milan using cross-laminated timber (XLAM) structural elements as part of the MIND project: a 13-story tower, Zenith, and an 8-story tower, Horizon.

In Sweden, however, they're thinking bigger: in Sickla, a former industrial area south of the capital, Stockholm Wood City is being built, "the world's largest solid wood neighborhood," according to developer Atrium Ljungberg. The development, which will include 2,000 new homes, 7,000 offices, schools, shops, and restaurants all made of wood, spanning 250,000 square meters, is unique in its scale and the priority it places on sustainable construction principles. Wood itself is a material that stores carbon rather than emitting it, as trees absorb CO2 as they grow. However, it can also reduce carbon emissions in construction management by up to 60% compared to traditional methods because it's lighter and quicker to work with than concrete, allowing for widespread use of prefabricated construction. It is no coincidence that the project is ahead of schedule and will be able to complete the building housing the schools by the end of this year, with the remaining thirty buildings scheduled for delivery between 2026 and 2027.

Another area under investigation to reduce the carbon footprint of buildings is the search for equally effective alternative materials to concrete. An Italian startup, BeNewtral, founded by PoliHub, the accelerator at the Polytechnic University of Milan, has entered the field this summer, launching a mineral binder alternative to cement. ReBind is a patented material created by exploiting non-hazardous industrial byproducts, which are transformed into a high-performance binder intended for non-structural applications, such as flooring, underlays, and cladding. Ongoing tests demonstrate that ReBind guarantees high fire resistance, good thermal stability, and durability comparable to or superior to traditional cements, while also having a much more favorable environmental profile. The data, validated under the European LIFE program, confirms a reduction of up to 90% in CO₂ equivalent per ton of product, a 98% reduction in energy required in the production cycle, a 93% reduction in water use, and the complete elimination of quarrying. BeNewtral co-founders Nicolò Verardi and Riccardo Frezzato describe their mission as follows: "We want to help redefine the paradigms of construction, a sector that still has a significant impact on the environment. We believe in a radically different model: regenerative, circular, and low-impact. An industry that not only reduces emissions but is capable of generating environmental, economic, and social value." ReBind's production process, in fact, is organized in local, flexible, and low-cost micro-plants, enabling the creation of value on a regional scale.

Research is also advancing into "living" building materials that absorb carbon dioxide from the atmosphere. So far, researchers have inserted carbon-eating bacteria into bricks, paints, and even a self-healing concrete that captures carbon dioxide and turns it into minerals. Now, a team at ETH Zurich has created a living material that can be 3D printed in various shapes. The material is a gel containing photosynthetic bacteria that trap carbon dioxide from the atmosphere, storing it in biomass, which then hardens over time. "As a building material, it could help store carbon dioxide directly in the buildings of the future," says Mark Tibbitt, professor of macromolecular engineering. Tibbitt and colleagues 3D printed various structures that allowed cyanobacteria to survive and grow for over a year. The printed structures are initially soft, but as the bacteria grow and form carbonate minerals, they harden.