EVALUATION OF THE VENTILATION STRATEGIES IN RELATION TO THERMAL COMFORT, INFECTION RISK AND ENERGY CONSUMPTION

Abstract

This study examined the “energy efficiency- thermal comfort- indoor air quality” dilemma.

Experiment was conducted to evaluate the performance of the four different ventilation systems: mixing ventilation (MV), displacement ventilation (DV), under-floor ventilation (UF) and personalized ventilation (PV) in a field environmental chamber (FEC). The cooling effect was analyzed using manikin-based equivalent temperature (Teq) of each of the 26 body segments of a breathing thermal manikin (BTM) and predicted percentage of dissatisfied (PPD) was used as an indicator for evaluating the performance of the ventilation systems.

Energy consumption and infection risk analysis focusing on MV and PV systems were further carried out for the comparison of the two systems under three different scenarios: hospital context and office context – from the perspective of the building owner and occupants. Objective functions were derived to evaluate the ventilation performance of the two systems with regards to energy consumption, thermal comfort and infection risk.

The results indicate the following: (1) at low air change rate (3 ACH-1), PV system is the best performing ventilation system with the least PPD. However at higher air change rate, the system will cause thermal discomfort to the users especially at the facial regions; (2) DV and MV systems have the greatest cooling effect at the users’ hand region while UF system has the least cooling effect across the body as compared to the other ventilation systems; (3) PV system has better ventilation performance as compared to MV system at 3 and 6 ACH-1 in all the three different scenarios.