The display of emotions in virtual agents’ behaviours is usually recognized as an important element to enhance their believability. Therefore, applications aimed at realistic simulations or entertainment have to consider this aspect. This paper presents a model for autonomous virtual agents that enables them to adopt behaviours that can be perceived by human observers as emotional. Our goal is to obtain believable behaviours for several simulation scenari like a waiting line where conflicts can emerge between agents. The proposed architecture is based on a principle of conservation and acquisition of resources.