Bachelorthesis Renée Einhaus

The increasing thermal stress on urban areas is placing new demands on climate-adapted building envelopes. Evaporation-based facades can help cool facade surfaces and adjacent urban spaces through the evaporation of water. However, their effectiveness depends on a reliable water supply, which has not yet been sufficiently investigated, particularly during heat waves with no precipitation. This bachelor’s thesis examined which strategies are suitable for developing building-integrated rainwater systems to supply evaporation-based facades.

The strategies were compared based on the requirements of the ACAW’s 2024 terracotta facade and a defined reference scenario using a weighted evaluation matrix. Suitable strategies were combined into three system variants in a morphological box and integrated into the reference facade as examples. The results show that building-integrated rainwater systems can store precipitation water and, when cooling is required, make it available for façade irrigation. This allows the water supply to be decoupled from individual precipitation events in terms of timing. However, universally applicable strategies could not be identified, as their suitability depends on the requirements of the respective facade as well as on structural, climatic, and site-specific constraints. The three developed variants reveal a trade-off between simplicity, supply reliability, energy demand, and construction effort. Overall, this study highlights the potential of building-integrated rainwater systems to decouple the water supply for evaporation-based facades from precipitation events and thereby harness their cooling effect even during dry heat waves. The developed variants represent conceptual solutions whose technical feasibility and long-term operational reliability must be further verified through quantitative calculations and experimental studies.

Prof. Dr. Jan Mehnert

Prof. Binke Lenhardt