It is necessary to manage room pressure strictly in order to prevent air flowing from outside for
maintenance of products quality in clean rooms. A local exhaust system is installed in a special environment in which
poisonous substances are handled to prevent the contamination. The reversal of pressure is not allowed under any
situation as for such the special environment while usual air-conditioning operation is done. However, it is difficult to
express room pressure changes of the air-conditioning system because present simulators do not have functions for
expression of presser propagation. In this research, a dynamic simulator of pressure control with MATLAB is expanded
in order to adapt to the more large-scale actual air-conditioning system. In addition, actual problems of the room
pressure changes can be simulated successfully