This paper provides the engineering framework for positive pressure filtered barn design, covering fan selection, static pressure budgeting and filter bank sizing. It is the reference the positive pressure design literature returns to, and it treats filtration as a ventilation problem rather than as a component specification.
The distinction matters because the disease literature and the engineering literature answer different questions. Dee and colleagues showed in 2005 that MERV 14 media prevented PRRSV aerosol transmission under controlled conditions, and the herd studies of Dee 2012, Alonso 2013 and Desrosiers 2023 showed the effect across farms. None of that work addresses whether a given building can move its required air through a given filter bank at the end of a service interval. Smith, Holck and Carman supplied field evidence on that question in 2019, finding that banks sited near an exhaust outlet lost lifespan significantly, and Janni and colleagues built a sizing and pressure model in 2018.
Static pressure budgeting is the practical core of it. Every element in the air path takes a share of the fan's available pressure, and filter media takes an increasing share as it loads. A design that balances at installation and does not balance at the end of the filter's life has not been designed for the way it will be operated. For a producer, the question to put to any proposal is what airflow the system delivers with dirty filters, because that is the condition the building spends most of its life in.