Phase change materials (PCMs) are materials with the ability of absorption of latent heat based on a phase change. PCMs are able to store and release a large amount of energy at certain temperatures melting or freezing. The aim of the research is to verify whether this phenomenon (material) can be used within an external thermal insulation composite system (ETICS). This is particularly the usage of PCMs in the base coat. The research is focused on two main areas. The first area concerns the water condensation on the surface of the ETICS and the associated phenomenon of algae attack. The second area concerns the warming of ETICSs with the use of dark color shades. Practical experiments showed a positive effect of PCMs on the heat-storage properties of the ETICS base coat. It was also experimentally verified that the PCM sample did not condense water vapor on the sample surface compared to the reference sample.