The gap between what existing HVAC systems deliver and what current infection control guidelines demand has created a compliance headache for commercial contractors. ASHRAE 62.1 focuses on minimum outdoor air ventilation rates measured in CFM per occupant, while ASHRAE 241 — Control of Infectious Aerosols — adds equivalent clean airflow requirements that many buildings cannot meet through ventilation alone. The Fellowes whitepaper provides technical guidance on closing that gap using in-room air cleaning devices as supplemental infection control measures.

For contractors, this matters because retrofit ventilation is expensive. Increasing outdoor air to meet infection control targets often requires new RTUs, larger ductwork, or significant air handler modifications. The whitepaper argues that portable HEPA filtration units can deliver equivalent clean air changes per hour (ACH) at a fraction of the cost, particularly in spaces like conference rooms, break areas, and open offices where occupant density varies. ASHRAE 241 explicitly allows equivalent outdoor air when delivered through filtration devices meeting MERV 13 or higher performance.

The technical approach outlined involves calculating the clean air delivery rate (CADR) required for a given space, then matching it with appropriately sized portable units. For a 1,500 square foot conference room with 10-foot ceilings and 20 occupants, achieving four equivalent ACH for infection control might require 1,000 CFM of HEPA-filtered air — either from three 350 CFM portable units or modifications to the existing system. The math is straightforward: room volume times desired ACH divided by 60 minutes.

Contractors should add this to their IAQ service offerings immediately. Start by auditing commercial clients for spaces that see variable or high occupancy — healthcare waiting rooms, school cafeterias, office training rooms. Measure existing ventilation rates using a flow hood, calculate the ASHRAE 241 equivalent outdoor air requirement, and quote the gap as either a duct modification job or a portable filtration package. Present both options with five-year cost comparisons. The portable route often wins on speed and budget, especially when the client needs compliance before next flu season.

The whitepaper also addresses maintenance planning. HEPA filters in portable units typically need replacement every 12-18 months depending on runtime and particulate load, creating a recurring service opportunity. That is measurable income compared to one-time duct modifications.