This chapter describes a state of the art AAL project in Kaiserslautern, Germany, which aims at monitoring inactivity patterns under real-world-conditions. Twenty flats have been inhabited by approximately 26 individuals since the end of 2007. The flats are equipped with several home automation sensors and actuators, thus allowing the collection of extensive data sets representing the typical user behaviour over long periods of time. Inactivity is the focus of the presented approach since it is assumed that inactivity and not activity is indicative of potential emergencies. The ultimate goal of the system is supporting senior citizens with modern home automation technology and thus helping them to maintain their independence and self-determination. In addition, illnesses and medical emergencies are to be detected by analysing and interpreting the captured sensor data. Based on this automated reasoning, appropriate help is administered to the persons affected. It is important to note that the development procedure of the Kaiserslautern AAL environment had been implemented from the onset as an evolutionary, user-centred design process to ensure user feedback and to allow easy identification of potential shortcomings or flaws of the developed solutions. Choosing such a user-centred design process facilitated meeting one of the paramount objectives of the AAL project, viz., that the AAL technology satisfies the users' needs and wants.