S07 - Session O1 - Cool down with vertical plants?

Authors: Maren Stollberg *, Alexander von Birgelen

Green infrastructure in the form of Living walls, is a climate change adaptation strategy for cities, as it has a cooling effect. Previous studies of the cooling effect of living walls come from other climatic zones, differ in the experimental design, or data were simulated via models. Measured temperature differences are highly variable and range from 2 to 30°C. Plant cooling capacity is explained by shading and transpiration and depends on physical plant parameters. In addition, there are environmental factors and system-related influences. A three years trial with a soilless living wall system was done between 2017 and 2019 at the experimental garden of the Hochschule Geisenheim University in Germany. Due to the textile-based living wall system, a large amount of water was needed for irrigation. The experimental setup includes four experimental walls which were exposed to the north, south, east, and west. We choose a high diversity of plants that prefer a moist or fresh habitat. The plant choice was divided into three plant mix variants: Cascade, Ground cover, and Seed, and in addition, we tested a control with no vegetation. The plant variants differed in species composition and therefore in for example coverage or leaf area. We measured the temperature with sensors and a thermographic camera. The main results were that the measured temperature is dependent on various factors. For example, the temperature varied at different distances from the living wall and during the day. And the different plants, plant mixtures, and their characteristics influenced the temperature. Thus, we were able to demonstrate a cooling effect of living walls for the building behind and its surroundings.