Yesterday a clinic retrofit spiked ESP to 0.95 in. w.c. after we added MERV 13s, and PM2.5 barely budged because the returns were undersized and leaky. Any CE that truly covers pairing MERV 13–15 with sane return velocities (about 300–400 fpm), ECM tuning, and CO2/PM verification so we protect lungs without starving airflow?
I’ve had the best luck with NCI’s Airflow & System Performance — set an ESP budget, resize returns to hit ‘300–400 fpm’, tune ECMs off the fan curve, then verify with CO2/PM logging: https://www.nationalcomfortinstitute.com/training/airflow-testing-and-diagnostics/.
Building on @jennifer_k23, ASHRAE ALI’s “Fundamentals of Air System Design” plus “Air Filtration and Disinfection” tie MERV 13–15 to 300–400 fpm returns, ESP budgeting, and ECM fan-curve setup (Professional Development). For IAQ verification, IAQA’s Advanced Filtration hits CO2/PM; think of the filter bank like a highway — add lanes to drop face velocity — do you have space for parallel 4-in racks to keep ΔP sane?