In recent years, VAV system has became more and more general in the field of air conditioning in our country, for it has some advantages such as energy saving, flexibility, easily automatic control, etc, On the other hand, the traditional PID control of this system often lead to coupling
, and the motor-driven dampers which serve as regulating devices are expensive, unsafe and waste great energy . Fuzzy control has obvious advantages over PID control, based on a new VAV system, it regulated the variable speed fan according to the fuzzy decision form. Thus , it cancels motor-driven dampers at the most degree and reduces coupling and saves energy .