Wall Greens
Moss covered concrete is combating climate change in the Netherlands
WASHINGTON, D.C. — In the Netherlands, there’s a modest apartment block in Purmerend where something extraordinary is growing—not in the ground, but up the side of the building. Installed in late 2023, the northeast facade of this social housing complex has been transformed into a living, breathing wall of moss. Covering 250 square meters and requiring no soil, planters, or permanent irrigation, this façade is more than just green. It’s a high-performance, climate-adaptive technology that absorbs CO₂, filters pollutants, and cools the building, all while looking surprisingly great.
A Greener Building
The project, known as "D’Groene Citer" (The Green Zither), was installed by HeMuBo and Intermaris, two Dutch firms committed to sustainable housing. They partnered with Respyre, a startup spun out of TU Delft that specializes in bioreceptive concrete. The technology at the heart of the facade—called VertiScape—is deceptively simple: a porous, nutrient-rich concrete made from recycled materials that provides an ideal surface for moss to colonize. With minimal watering during the first few months, the moss takes hold and begins to thrive on its own. Once established, it lives on rainwater and humidity alone.
From a distance, the effect is transformative. What was once a cold, gray wall is now a vibrant living surface that changes with the weather, the seasons, and the light. But what makes the project more than aesthetically pleasing is what it does for the people living there, and for the climate. This single wall is estimated to absorb over 350 kilograms of CO₂ annually, trap more than 7.5 kilograms of nitrogen oxides, and filter out 75 kilograms of ammonia and 1.5 kilograms of fine dust. That’s the equivalent of planting 17 mature trees, all on a surface that used to be dead space.
The Purmerend installation isn’t the only one. In the past year alone, Respyre has completed similar projects in Oostrum, Alphen aan den Rijn, and even internationally in Kortrijk, Belgium. At an industrial site in Oostrum, a 450-square-meter moss facade now cloaks the side of a commercial building, sequestering CO₂ and lowering wall temperatures by more than 10 degrees Celsius. In Alphen, the office of Bloemen Architecten now features a moss wall, serving as both an environmental element and a design statement.
Moss Effect
What sets Respyre apart is that they’re not in the business of green walls as we typically think of them. There are no steel frames, no soil beds, no complex irrigation networks. Their bioreceptive concrete is the wall. And that subtle distinction changes everything. "Our system is passive, low maintenance, and light-weight. It doesn’t require you to retrofit a building with extra support structures," said Respyre CEO Auke Bleij in a statement. "We see moss as a pioneer organism—resilient, adaptable, and incredibly efficient."
And they have a point. Moss is an underrated powerhouse. Unlike typical green wall plants, moss requires no root systems or soil, meaning it can grow in places most vegetation can’t. It clings to vertical surfaces using rhizoids—tiny filaments that anchor without damaging the material beneath. It survives on rain, dew, and ambient humidity. And it thrives in polluted environments, even feeding on airborne particulates and gases.
The science backs this up. According to performance data released by Respyre, a single square meter of moss facade can absorb approximately 0.5 kilograms of CO₂ per year. Multiply that across a city block, and you're not just creating a greener aesthetic—you're building real climate infrastructure. The panels also reduce the urban heat island effect by passively cooling their surroundings. In trials, moss-covered facades registered surface temperatures up to 15 degrees Celsius cooler than bare concrete on hot days.
There's also the question of water. Because of its high porosity, the concrete acts like a sponge, absorbing and retaining rainwater, then releasing it slowly through evaporation. That makes it a tool not just for air quality, but also for stormwater management. In a time of increasingly frequent and intense rainfall, that matters. And because the moss requires no trimming or pruning and doesn’t attract pests, maintenance is minimal. Once it's in, it's in.
Circular Center
Bleij and his team have also prioritized circularity. The concrete itself is made from up to 95% recycled material, including construction waste. It’s low-carbon from the start, and gets more climate-positive as the moss matures. The system is flexible enough to work on new builds or retrofits. It’s being tested on wind turbine bases, apartment balconies, and the facades of schools and office buildings. "We want to make it easy to integrate nature into places it’s usually excluded from," Bleij explains.
They're not alone. A handful of similar companies have emerged in recent years, most notably Green City Solutions in Germany, whose CityTree and CityBreeze units combine moss with smart air filtration systems. Another is BryoSystem in Germany, which uses prefabricated moss modules with solar-powered irrigation. These are exciting, but often require more technology, more energy, and more maintenance. Respyre’s offering is humble by comparison—and that may be its superpower.
For cities looking to scale green infrastructure without the overhead, Respyre offers something rare: a low-cost, low-complexity, high-impact solution. It’s elegant, effective, and largely invisible in its operation. As climate adaptation moves from concept to necessity, materials like this become essential. We need buildings that do more than just shelter. We need buildings that clean, cool, and care.
So far, Respyre has stayed close to home. Most of its projects are in the Netherlands, where the company benefits from a strong culture of urban planning and climate innovation. But international interest is growing. The project in Kortrijk, Belgium was their first step abroad, and there are whispers of pilots in the UK, France, and beyond. As cities scramble to retrofit their infrastructure for a hotter, wetter, more uncertain future, Respyre's moss may be just the quiet revolution we need.
Because maybe the best way to rewild our cities isn’t through grand gestures, but through simple, scalable shifts. Like turning a blank wall into a miniature forest. Like letting moss do what it’s done for millions of years—grow, adapt, and endure.
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