Smart buildings are automated buildings that deliver essential services to the modern society. These buildings reduce the energy consumption of homes, increase the safety of inhabitants, increase the comfort for employees and reduce operating cost by automatically operating elevators, heating, ventilation, and air-conditioning, and perform essential services within large infrastructure buildings, e.g. smart video surveillance on airport terminals. Today's smart buildings are equipped with a steadily increasing number of features while providing rather limited security features. Hurdles to increase the security of smart buildings are rooted in several reasons. For instance, new buildings are usually required to be compatible to older components integrated decades ago, which do not provide any security features. The patchability of controller software is another unsolved problem, and the integration of state-of-the-art security features into these old operating environments is difficult due to limited computing power and memory of legacy systems.