Ceiling personalized ventilation combined with desk fans for reduced direct and indirect cross-contamination and efficient use of office space

• Cross-infection occurs by direct inhalation and contact of contaminated surfaces.
• Mixing ventilation performance is degraded at reduced distance between occupants.
• Ceiling personalized ventilation reduces significantly cross-contamination.
• The optimized system induces large energy savings compared to mixing ventilation.
• The optimized system improves the occupation density from 12 to 8 m2 per occupant.

Crowded offices with short distances separating workers’ stations increase the probability of respiratory cross-infection via two different paths. One path is the contaminant transmission through air by direct inhalation and the other is through the body contact of contaminated surfaces and walls. Mixed ventilation principles used today reduces the probability of cross contamination by increasing the distance between the stations challenging the efficient use of the space or by supplying more fresh air in the space which is energy inefficient.In this work, new cooling and ventilation configuration is studied by modeling using computational fluid dynamics with consideration of space occupancy density while providing good indoor air quality. The configuration considers a ceiling personalized ventilation system equipped with desk fans. The ability of the computational fluid dynamics model in computing the thermal, velocity and concentration fields was validated by experiments and published data. The main objective of the performed experiments was to ensure that the developed computational fluid dynamics model can capture the effect of the desk fan flow rate on particle behavior.The studied system is found to provide acceptable indoor air quality at shorter distance between the occupants compared to the mixing system at considerable energy savings. By optimizing the design of the proposed personalized ventilation system, the occupancy density in an office is enhanced to 8 m2 per occupant compared to 12 m2 per occupant for conventional mixing system while maintaining better indoor air quality at significant decrease in the energy consumption.