If the area of a computer room is 60 sq meter(S=60), the net height is 3 meters(H=3), and there are 10 persons(N=10) in it. If it is calculated according to “Personal fresh air consumption”, and assume that:Q=70, the result is Q1=N*Q=10*70=700m³/h If it is calculated according to “Air change per hour”, and assume that: P=5, the result is Q2=P*S*H=5*60*3=900m³/h Since Q2＞Q1，Q2 is better for selecting the unit. As to special industry such as hospitals(surgery and the special nursing rooms), labs, workshops, airflow required should be determined in conformity with regulations concerned.