Samuel pioneers seagrass as a sustainable insulation material
To meet the Netherlands’ climate targets, significant changes are needed. The construction sector, in particular, must take substantial steps to reduce its carbon emissions. Samuel van Dijk (22), a graduate of the Architecture and Construction Engineering(opens in new tab) programme at Windesheim University of Applied Sciences, is the founder of Zostera, a start-up developing sustainable insulation made from a natural marine by-product that stores CO₂ rather than emitting it. With his innovative solution, Samuel hopes to accelerate the transition towards a more sustainable built environment through the use of bio-based materials.
An idea rooted in childhood
The origins of Zostera can be traced back to an idea Samuel first had at the age of twelve. For a school project, he designed a sustainable house insulated with seagrass, inspired by a story his grandmother had shared.
"I still remember my grandmother showing me an article about a house on an island in northern Denmark with walls and a roof made of seagrass," Samuel recalls. "She was amazed by its properties: it lasts for decades, is fire-resistant, absorbs CO₂, repels water, provides excellent insulation and naturally resists mould." The project went on to win the national final of a school competition, and the concept remained at the back of his mind for years.
At seventeen, Samuel took his first steps into entrepreneurship. Through a school assignment, he created a 3D model for the redevelopment of Lübeckplein in Zwolle, which led to a commission from the municipality of Harderwijk. This resulted in the registration of his first company with the Dutch Chamber of Commerce: a technical design consultancy specialising in construction drawings and Building Information Modelling (BIM).
During his degree at Windesheim, Samuel connected with the Windesheim Centre for Entrepreneurship. "During a conversation with Cankut Ercan, I mentioned my ambition to do something with seagrass and my mission to make the construction industry more sustainable through circular, scalable and practical solutions." That conversation marked the beginning of Zostera, named after Zostera marina, the Latin name for eelgrass.
Supporting the circular and energy transition
"In less than five years, by 2030, the Netherlands aims to have nearly one million climate-neutral homes," Samuel explains. "By then, we are also expected to meet national climate targets, including 30% bio-based construction, 50% circular construction and, by 2050, zero construction waste. That means we need scalable solutions with low emissions that can be implemented quickly."
He believes existing bio-based materials often struggle to scale. "The strength of our insulation material is precisely that it can be produced at scale. Seagrass is one of the few bio-based resources that does not depend on agriculture."
One of Zostera’s greatest challenges is the conservative nature of the construction industry. Convincing contractors and clients to adopt an unfamiliar insulation material is not always straightforward. "Fortunately, we're seeing growing interest from companies that want to launch pilot projects with us. The industry has reached the point where this transition is no longer optional. Businesses need to embrace it if they wish to remain future-proof."
Zostera is the start-up founded by Samuel van Dijk. In 2025, he received Windesheim’s Student Entrepreneur of the Year award, which included a year's complimentary membership of ZWINC(opens in new tab), the university's innovation hub.
Where education, research and entrepreneurship come together
In 2024, Samuel began developing Zostera in earnest. He personally travelled to Germany to identify suitable suppliers and became the first entrepreneur to establish a reliable supply chain for clean, processable seagrass.
Since the beginning of this year, progress has accelerated. Samuel was named Windesheim Student Entrepreneur of the Year 2024–2025, earning a year of free membership at ZWINC. This provides him with dedicated workspace, access to an extensive professional network and guidance from an experienced team of business coaches.
Every fortnight, he meets with five specialist coaches, each focusing on a different aspect of building the company, including market validation, business development, scalability and marketing.
After graduating, Samuel also presented Zostera at InnoMatch, an event organised by Rabobank, ZWINC and Biltin that connects start-ups with established businesses. In his pitch, he invited entrepreneurs to test Zostera's insulation products in pilot projects.
For this initial testing phase, the company is focusing on the renovation market, where technical challenges are generally greater. Once the product has proven itself there, expanding into new-build projects will be the logical next step.
The power of innovation through collaboration
One of the Netherlands' greatest challenges is achieving its climate ambitions in areas such as carbon reduction, nitrogen emissions, biodiversity and water quality. Addressing these issues requires continuous innovation and close collaboration between government, industry and civil society.
A strong start-up and scale-up ecosystem is therefore essential to the innovative capacity of the regional economy. Windesheim actively contributes by bringing together education, applied research and entrepreneurship. Together with regional partners, the university is working towards a carbon-neutral built environment by 2050.
One such partner is Biltin, based in Zwolle's Spoorzone district. Biltin works alongside professionals, lecturers, researchers and students to develop sustainable innovations for construction firms, installation companies and other organisations involved in the energy and resource transitions within the built environment.
Looking ahead
Meanwhile, Samuel's workshop at ZWINC already contains around 1,200 kilograms of seagrass. "The seagrass arrives dried and compressed into bales. We process it into boards, rolls and insulation mats. It's a highly complex production process, and that's precisely where our unique expertise lies."
Pilot projects with launch customers are scheduled to begin in 2026, followed by the commercial introduction of the product. "By next year, I hope to move into larger premises because we need significantly more storage capacity. By mid-2026, I expect to have our entire production process fully operational - from raw material to finished product."