An evaluation index for the control effect of the local ventilation systems on indoor air quality in industrial buildings

To evaluate the control effect on indoor air quality (IAQ) of the local ventilation systems in industrial buildings with centralized contaminant sources, a new index, namely, normalized concentration in the target zone (NC-TZ), was proposed in this paper. According to theoretical analysis, NC-TZ is non-dimensional and ranges from 0 to 1. When NC-TZ tends toward 0, the control effect of the local ventilation system on IAQ is more satisfactory. When NC-TZ tends toward 1, the control effect on IAQ is less satisfactory. The numerical simulation on a push–pull ventilation system with varying exhaust flow rates and varying distances between push and pull hoods was performed. The results demonstrate that for the same capture efficiency, changing the local ventilation system characteristics can change the control effect on the local environment. The results for obstacles at different positions also indicate that NC-TZ can clearly reflect the control effect on IAQ of the local ventilation systems in industrial buildings.