The work presented in this paper is focused on the design and the implementation of an adaptive framework for ambient assisted living applications. The challenge is to provide an approach able to deal with a dynamic environment in order to provide an adequate service to the person. The evolution of the intrusion level of the system based on the degree of urgency and the availability of different communication devices that constitute the environment are particularly targeted. The results obtained with the coalition-based multi-agents system are promising and reflects these constraints.