Open Access

Luca Biedrowski

• Urban areas are highly vulnerable to the impacts of climate change, especially regarding increased air temperatures, changes in wind ventilation and precipitation patterns. This vulnerability is mainly due to limited vegetation, sealed surfaces and a high density of buildings. As cities continue to expand and urbanization is accelerating worldwide, more people will be exposed to these conditions, which increases pressure on urban infrastructure and public health. This master‘s thesis investigates the urban climate in the city center of Freising in Germany, with a focus on heat island effects and thermal stress under current and future climate conditions. The microclimate model ENVI-met was used to simulate the urban climate in different scenarios: (A1) the current state of Freising in July 2024, (A2) the future scenario based on RCP4.5 for the period 2041 – 2070, (A3) another future scenario for the same period based on RCP8.5, and (B) a scenario with increased tree canopy cover as an optimized version. The simulation results provide data on potential air temperature, relative humidity, wind speed and thermal comfort for the four different simulation scenarios. The key findings are discussed and compared to fundamental theories of urban microclimatology to evaluate the impact of vegetation on the microclimate. The analysis revealed significant differences between the scenarios regarding the potential air temperature. Under both RCP projections, the situation in Freising experienced higher thermal stress with more extreme air temperature and lower relative humidity levels. In contrast, the adapted design showed significant cooling effects on the stressed urban climate, by increasing shading and evapotranspiration rates. In addition, a very high thermal stress was found in large parts of the study area across all scenarios. The study shows challenges of urban design and highlights the importance of sustainable planning with sufficient vegetation levels.