This paper presents a distributed cognitive architecture suitable for Ambient Intelligence applications. The key idea is to model an intelligent space as an ecosystem composed by artificial entities which collaborate with each other to perform an intelligent multi-sensor data fusion of both numerical and symbolic information. The semantics associated with the knowledge representation can be used to aid intelligent systems or human supervisors to take decisions according to situations and events occurring within the intelligent space. Experimental results are presented showing how this approach has been successfully applied to smart environments for elderly and disabled.