EXP COVID-19 Offices White Paper

In office buildings that utilize overhead mixing systems, Upper Air UV can further reduce risk.

ENERGY RECOVERY Many Dedicated Outside Air System (DOAS) units and fresh-air Air Handling Units have energy recovery incorporated into their systems to recovery energy from the return air as it is exhausted to the outdoors. Units shall be designed to incorporate energy recovery approaches that do not have the potential to leak back to the fresh air stream being supplied to the space. Heat pipe,

remain uncaptured by the HVAC system. Such a system will inactivate the viruses before they can fall into the occupied zone. Ventilation patterns (natural and mechanical) should promote good air mixing in a space equipped with UVC so that infectious microorganisms are drawn through the UVC “kill zone.” In office buildings that utilize overhead mixing systems, Upper Air UV can further reduce risk. FAR UV

Figure 29. UVC Air Handling Unit and Ductwork Application (30, 42)

Far-UV is emerging an option that can provide airborne mitigation in a vertical direction downwards rather than projected horizontally across the upper-air level. TiO2 PCO OR TITANIUM DIOXIDE PHOTOCATALYTIC photocatalytic air purifier, ultraviolet light shines onto a titanium catalyst, which converts molecules of pollution into more OXIDATION In a titanium dioxide

pump around and air to air heat exchangers should be considered. Existing air handling systems with energy recovery should be reviewed by a qualified engineer to confirm if modifications should be made. If systems do have the potential to leak virus from the exhaust air stream to the fresh air stream exist UVC installed downstream in the fresh air path will eliminate the potential source pathogen source. UPPER AIR UVC Various upper-air UVC devices are designed to generate a controlled UVC field above the heads of occupants and to minimize UVC in the lower, occupied area of the room. The primary objective of upper-air UVC is to interrupt the transmission of airborne infectious pathogens with the indoor environment. For occupied spaces with lower ceilings, various louvered upper-air UVC devices (wall- mount, pendant and corner-mount) are available for use in combinations and are mounted with at least 2.1 m from the floor to the bottom of the fixture. The fixture should be mounted so that its UV energy is distributed parallel to the plane of the ceiling. Device construction and placement prevent excessive ultraviolet energy from striking occupants below. In areas where there is not a viable opportunity for duct mounted UVC (i.e. spaces with minimal or no ventilation), upper-air UVC is a very promising approach. Even if space is ventilated and has duct mounted UVC, upper-air UVC could provide a redundancy where floating viruses may

Figure 30. Typical Elevation View showing UVGI energy placed above heads of room occupants (28)

Figure 31. Upper Air UV can reduce Path 3 Risk in gaming areas that have overhead supply air systems

harmless substances. The big advantage that photocatalytic air purifiers have over other air-cleaning technologies is they completely transform the harmful chemicals and effectively destroy them. While the standard PCO approach does not affect viruses; the ultraviolet light used in the process does (see figure on the right.)

SOLUTIONS TO EFFECTIVELY COMBAT COVID-19 IN OFFICES

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