Critical analysis of contaminant removal efficiency assessment in a ventilated room

This study presents a critical analysis of assessment of ventilation systems effectiveness in terms of contaminant removal. For this purpose, experimental measurements are carried in a room of an experimental house called MARIA. Various ventilation scenarios are handled. The ventilated room is also equipped with a pine wood floor which emits several Volatile Organic Compounds which are considered as air pollutants here. Thereafter, based on boundary conditions given by measurements, Computational Fluid Dynamics (CFD) simulations are performed. CFD results are compared to measurements to check their accuracy. Moreover, air quality within the ventilated room is numerically analyzed via indices. The usual contaminant removal effectiveness index and the air quality number Nc (defined by Awbi) are used. On the one hand, it is noted that although can
especially reveal the characteristics of contaminant distribution; it is not suitable for assessment of the contaminant removal efficiency of ventilation scenarios with different air flow rates. Indeed, its definition does not take into account absolute contaminant concentrations levels. On the other hand, Nc can not reveal the air pollutant distribution pattern. Nevertheless, whatever the ventilation rates, Nc classifies relevantly the ventilation scenarios. Indeed, the lower the contaminant concentration within the room is, the higher Nc value is, and thus more effective the ventilation system is. It can thus be used in addition to the usual index to compare contaminant dilution effectiveness of ventilation systems with different air flow rates.