In the design of the exhaust hood, e.g. kitchen ventilation, the
exhaust hood design based on the face velocity includes the
possibility of leakage from the control target domain. In this
case, the vector distribution of NEV* in the hypothetical boundary of the target domain will provide the useful information
concerning the leakage of the contaminant across the
boundary. We believe that the validity and contribution of NEV
on the control of Indoor air quality and on the ventilation design
are high.