Currently, there are quite a number of computational systems that attend to humans automatically, e. g., using natural language. However, the interaction with these machines is still too artificial. Usually, these machines are insensitive to the emotional content being expressed by the communication partner, as well as incapable of expressing emotional content. This paper presents the architecture of a computational system to simulate emotional states. The simulator is split up in three modules that provide to the designer a great number of possibilities to model different aspects of a simulated emotional personality. The model of transition between different emotions is based on a Fuzzy Finite States Machine. This allows the system to be in several emotional states simultaneously with certain degree. As a demonstration of concept, we present a prototype where the emotional content is based on the environmental conditions of light and temperature.