Three new scales for measuring ventilation efficiency in a room are defined in order to evaluate the distributions of "ventilation effectiveness" at each point in a room. They are calculated based on the distributions of contaminant concentration in a room.

1. SVE1 (Scale for Ventilation Efficiency 1): the spatial average of contaminant concentration in a room where contaminants are generated at a single-point source. It is a function of position, because the averaged value differs according to the location of each source point. This value is defined as a representative of spatial distribution.

2. SVE2: the mean radius of contaminant diffusion in a room. It is defined as the standard deviation of contaminant distribution. It is also a function of position and is defined as another representative of spatial distribution.

3. SVE3: the concentration at a given point in a room, where the contaminant is uniformly generated throughout the room.

SVE1 and SVE2 for one point are calculated from the distribution of contaminant concentration where the contaminant source is located at the point in question. Therefore, SVE1 and SVE2 for all points are obtained by changing the position of the source point to include the entire space. In order to confirm the usefulness of these new scales, the characteristics of ventilation efficiency in an actual conventional flow type of clean room are analyzed by these scales, which are given by calculating the results of threedimensional numerical simulation of flow and diffusion field based on the k-ε two-equation model.

Units: SI