The aim of the doctoral thesis is the investigation, quantification and optimization of the physical effects and interactions of house trees. Based on an extensive analysis of vernacular buildings, in which the so-called house tree was used to improve the indoor climate, the current literature on the potential effects of (house) trees is evaluated and summarized. Thereupon, a numerical model for the simulative analysis of the physical potentials of house trees for indoor spaces is developed and validated by measurements. Finally, with the help of the numerical model, concrete recommendations for the use of house trees to maximize the effective potentials are defined.