This paper presents the design of a fuzzy reasoning expert system for
the achievement of thermal and visual comfort in buildings. This syste
m does not demand the precise mathematical model of the building to ac
hieve the control law but uses high-level control Variables such as th
ermal and visual comfort. The powerful interactions of the passive com
ponents and of the comfort subjectivity match with the application of
the fuzzy control theory entirely. Mathematical models are presented,
where the actions of the actuators are applied. The design of the rule
base is described and, finally, the system is evaluated by using exte
nsive, worst-case, simulation results.