More and more houses are being insulated by means of external thermal insulation composite systems (ETICS). Whilst this saves energy, the façades are increasingly being colonized by algae. This is not only detrimental to the aesthetics but also to the diffusion capacity of the surface coating. Moisture damage can thereby result. In order to reduce algae growth, façade coatings containing biocides have often been used up to now. The problem here is that the biocides are leached out within a few years. Consequently, environmental pollution and increasing algae growth on the façade can occur. In collaboration with industry partners, we are developing a bio-based, weather-resistant façade paint that will physically prevent microbial growth. It could provide ETICS façades with long-term protection against algae - without any biocides whatsoever.