The construction industry consumes enormous resources and is responsible for a large proportion of global CO2 emissions. The HopfON team wants to change this situation. Their vision: to produce recyclable, climate-friendly building materials from agricultural waste and resources.

The idea came to them over a beer in their student dorm. Thomas Rojas Sonderegger, a civil engineering student at the time, was telling management and architecture student Marlene Stechl about a lecture he had attended about a Colombian who was using banana fibers to make building materials. "We thought it would be great if we could produce our own local building material. That would save greenhouse gas emissions," says Marlene Stechl. "We thought about what solution could work in Bavaria. We were actually joking when we said: It would be cool to use hops. The next day we actually started researching.

A promising fiber-based material
The two students soon learned that hops come from the same plant family as hemp, which has become increasingly important as a construction material in recent years. "We started to gather more information about this plant - and what actually happens to the waste material from hop cultivation," says Marlene Stechl. They found a supporter in Professor of Architecture and Design Niklas Fanelsa, who not only contributed his scientific expertise, but also gave the team access to the Bioregional Design Lab at the TUM, enabling further material testing.

The first step in the production process of the building materials is the mechanical separation of the fibers from the hop vines. Through further chemical processing, the hops are turned into panels that serve as acoustic insulation.

Since only a small percentage of the hop harvest is used for beer production, Stechl and Sonderegger came up with the idea of using the hop growers' waste as well. "In addition to the environmental benefits, this also saves costs," says Stechl. The fibrous structure of the hop plant gives the material tensile strength, making it particularly suitable for acoustic panels, insulation and structural panels. The woody core of the hop, known as the shives, adds compressive strength to the material. Like hemp, hops also have good thermal insulation properties. To validate the team's choice of material, Marlene Stechl tested the flammability of the hop plant as part of her master's thesis and found no cause for concern.

Excellent idea
With their idea, Stechl and Sonderegger took part in the Urban Prototyping Lab of the TUM Chair of Architectural Informatics. Participants were invited to propose solutions to problems in the construction industry. After submitting their detailed concept, they were invited to apply for the 2022 TUM IDEAward. They won the first prize, which came with 15,000 euros in seed capital.

The TUM IDEAward caught the attention of former business student Mauricio Fleischer Acuña, who soon joined the HopfON founding team. He was followed in 2023 by Matthias Steiger, a biochemist working on his doctorate at the Chair of Chemistry of Biogenic Resources, who is now developing further prototypes for HopfON. HopfON also received the TUM Booster Grant, which includes one-year funding of 45,000 euros, and two prototyping grants from UnternehmerTUM, the Center for Innovation and Entrepreneurship. The support through the TUM Start-up Consulting and the TUM Venture Labs is of such great help, especially when it comes to ramp up operations and founding the company in 2024, as Mauricio Fleischer Acuña explains. Another key pillar is the location: the world’s largest hop growing region, Hallertau, is on Munich’s doorstep.

Logistical challenges of the hop harvest
The hop harvest in the Hallertau in September 2023 proved to be a major challenge for the HopON team. "We didn't know anything about containers, transport companies or drying sheds," says Marlene Stechl. "We had to learn the whole logistics chain. It was really experimental work for us. For example, they had to figure out the best way to separate the hops from the horizontal wires along which the plants are trained.

In their first harvest, the founders got a lot of help from the farmers they worked with. Harvesting the plants for HopfON was also new territory for them. But they were happy to be involved. "It was just great. I felt that if you have a vision and share it, you can expect an amazing response," says Stechl. With such energetic and creative support, the team was finally able to set up a process to secure enough raw material for the coming year's production. This was crucial, says Mauricio Fleischer Acuña, because hops are only harvested once a year.

A recyclable product
It is important to the founders to offer a recyclable product. For this reason, they completely avoid the use of artificial or insoluble additives. This means that the hop-based construction materials can be broken down into their original components after use and reconstituted into new products. According to Mauricio Fleischer Acuña, this is an important unique selling point compared to other sustainable materials. It is also an essential prerequisite for the market launch planned for 2024 with the introduction of acoustic panels for soundproofing applications.

The biggest challenge at the moment? Just keeping it all going - because some of the founders have full-time jobs in addition to their HopfON roles. But their goal is a great motivator, says Stechl. "We're working towards the day when we can offer a serious alternative to conventional building materials."