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Spaces with high occupancy density like classrooms present challenges to ventilate due to high thermal loads. In order to meet occupants' perception of thermal comfort in such spaces, traditional systems (i.e. mixed ventilation (MV)) consume a lot of energy. Alternative ventilation strategies have been proposed to reduce the energy consumption of ventilation systems in crowded places while maintaining the occupants' well-being. One strategy is to supply a downward intermittent pulsating airflow directly on the occupants' head (the most sensitive body part to airflow change). This will increase the convective heat transfer allowing comfortable operations at elevated room temperatures thus, at lower energy consumption.

In this work, a newly proposed intermittent air jet system (IAJS) is investigated to study whether transient ventilation supply can result in acceptable levels of thermal comfort in classrooms spaces at reduced energy cost. This air distribution system supplies air at high momentum with an intermittent pulsating (ON-OFF) profile into the classroom. The energy performance of a classroom ventilated using MV was compared to that ventilated using an IAJS system, assuming same fan size.

A transient 3-D computational fluid dynamic (CFD) model of a classroom ventilated with two different ventilation systems (MV and IAJS) was developed to assess the velocity and temperature fields around the students. In addition, the CFD model was coupled with a transient bio-heat model to compute the segmental skin temperature of the human body. The overall thermal comfort and thermal sensation were assessed using the published comfort model of Zhang. This combined model compares the energy consumption associated with ventilating a classroom using a) MV and b) IAJS while assuming the two ventilation systems to be achieving the same level of thermal comfort in the occupied zone. It was found that with 40% energy savings, the IAJS with a supply temperature of 22C was able to produce the same level of thermal comfort as the MV system in the classroom.