The design of smart buildings requests assistance systems, which grant the intuitive integration of users and visitors into cooperative building arrangements. In this paper an adaptive assistance system is proposed with the ability of implicit man-environment-communication to react customized to specific user preferences distributed by mobile devices. Embedding methods of knowledge processing into distributed systems is a key factor for enabling the cooperation of a user’s mobile device and a smart building. Using the semantic knowledge description language OWL and meta services, technical devices, house establishments and internet services can interact in order to support the user’s preferences. With the example of a straightforward ontology it is shown how a presence control switch is semantically modeled in description logic and the integration of the whole ontology in modern building services management control can help saving energy using mobile devices. As a result the paper shows how a maximum of comfort can be combined with a maximum of energy efficiency in the use of a day to day office life.