The building Willersbau on the Dresden University Campus will be refurbished during the next years. In this context, parts of the inner courtyard’s old tree stand will be eliminated. To compensate, the redevelopment plan includes a concept for regreening. With the software ENVI-met, this work conducts a model-based analysis of the refurbishment’s short- and long-term effects on the micro- and bioclimate in the area of Willersbau. The models are parametrized and simulated for autochthonous summer conditions before, one and 26 years after the refurbishment on the 15.06.2019, 2027 and 2052. The impacts on microclimatic conditions and thermal comfort was analysed by assessing the statistical, spatial, and temporal distribution of the bioclimatic index UTCI (Universal Thermal Climate Index) and the mean radiant temp., potential air temp., specific humidity and wind speed. The cumulative thermal stress of pedestrians during busy time periods was investigated at four receptor points, located at commonly frequented sites. Simulation results show that the long-term area-averaged thermal comfort in the study area improves with an overall increasing vegetation volume. This trend also applies for the refurbished courtyards. During daytime, vegetation and buildings decrease the mean radiant temperature and therefore improve thermal comfort. Nevertheless, several deteriorating effects of an increasing vegetation volume on thermal comfort were identified, such as increased specific humidity. Besides, the replacement and new allocation of vegetation plays a critical role for future site-specific thermal comfort. The analysis revealed a short- and long-term increase in heat stress at the investigated receptor points. It was thus possible to identify sites of thermal discomfort and supply ideas for mitigation.