I. Original Idea for a Green Facade
With rising temperatures posing an increasing burden on urban populations, we have developed a system for greening facades as a provider of specialized sustainable solutions, aiming to achieve several goals:
– Microclimate Improvement: In addition to insulating buildings, where insulation material usually consists foamed polystyrene, a green facade would enhance the microclimate by cooling urban areas, purifying air, and providing noise protection.
– Space Efficiency: The city becomes greener without occupying valuable space. We emphasize complete recycling of the system and resource-saving production.
– Modular Design: The modular structure allows for selective, needs-oriented replacement. Mosses serve as the planting material due to their unique characteristics: adaptability, simplicity, and resilience.

II. The Development Process
Biodegradable Substrates for Sedum Mats
Various biodegradable materials were tested as substrates for sedum mats, including loofah cucumber, hemp mats, and coconut mats. These materials tended to promote fungal growth, and after one year of weathering, the sedum plants did not show significant integration with the substrate. A test module with houseleek on jute performed better: after one year, the houseleek and jute were in good condition, but achieving mechanical stability required significant effort, such as using bamboo wood frames. Generally, sedum mats need a soil-like substrate for long-term growth, which leads to a weight issue for the intended components.

Tests with Mosses
Mosses are the second-largest plant family after flowering plants, with biologists estimating around 20,000 species worldwide. Some species can survive temperatures up to 70°C, but cultivating mosses is still a relatively young field. We obtained various moss mixtures from a German company specializing in mossing buildings, walls, stones, etc. These mosses grow on wood (e.g., robinia bark) and various natural fiber materials (seagrass, hemp, etc.). Although fungal infestation can also be a concern here, certain wood species are highly resistant to fungi, including larch, robinia, sweet chestnut, and Douglas fir.

Tests with Ferns
Following initial growth trials, tests with ferns are currently not being continued. However, in principle, the European spotted fern could be suitable as an epiphyte for growing on rough surfaces.

Alternative Substrates Made from Recycled Material
In addition to porous recycled foam glass, a mat made from recycled PET (rPET) appeared particularly promising. Although the material does not meet the requirements for biodegradability or compostability, it would give used PET bottles a second meaningful use. Panels made of rPET, which can be easily equipped with irrigation nozzles, are currently being constructed and tested.

III. Summary

Our findings indicate that moss mixtures are suitable for growing on various substrates. Mosses on wooden substrates show very good long-term stability. From today’s perspective, metal fasteners (screws, nuts, etc.) are necessary to attach wood-based substrates to a ventilated facade, which contradicts the requirement of biodegradability. However, wood species that are highly resistant to biological attacks and decompose or rot very slowly can still be selected.
Test modules with rPET panels featuring moss growth and irrigation are currently under construction. Our project aims to significantly enhance urban living conditions through innovative and sustainable greening solutions. Using mosses and recycled materials is a crucial step in minimizing environmental impact while improving the quality of life in cities.