The work describes an air conditioning and circulation system of a clean room environment in of a semiconductor production site. It is based on given requirements for air cleanness, temperature preasure and relative moisture. The first half of the work describes the way the system should work, classification of construction and operation of the site. The second half describes the calculations of the given parameters on which the system is designed. The calculations deal with - Air exchange and maintaining the required parameters - Designing the muti stage air filtration system - Designing the air flow speed, intake and outlet parameters of the air conditiong distribution system - Desingning the air conditioning units and their possitioning in the utility room