Evaluating the ventilation effect of different ventilation types by occupant air exchange efficiency

Evaluation of the ventilation effect and indoor air quality in ventilated rooms is very important for ventilation system design. Air-exchange efficiency is widely used to indicate ventilation effect and IAQ; however, it does not take into account occupant distribution in the room and thus is limited.
The authors have proposed a revised air exchange efficiency, that is, the occupant air exchange efficiency, to indicate the ventilation effect by considering different occupancies (Zhao et al. 2003a). This paper employs occupant air exchange efficiency to evaluate the ventilation effect of four ventilation types, and two different occupant distributions are considered. Ten cases including side-up supply and side-low return, ceiling supply and side-low return, personalized ventilation and
displacement ventilation, are studied. The rooms are differentiated between different zones by giving different occupied density to take the occupant distribution into account, which
is not similar to the traditional method, which uses the breathing zone. By numerical analysis of the occupant air exchange efficiency for all the cases, it is found that ventilation effects are different under different occupant distribution conditions. It is better to use occupant air exchange efficiency to evaluate the ventilation effect and indoor air quality for actual application, instead of the traditional air exchange efficiency.