Performance and Costs of Particle Air Filtration in HVAC Supply Airstreams

This paper uses a model, and data on particle size distributions, filter efficiencies, and particle deposition rates to estimate the reductions in the indoor mass concentrations of particles attainable from use of filters in HVAC supply airstreams. Additionally, the energy and total costs of the filtration options are estimated. Predicted reductions in cat and dust-mite allergen concentrations range from 20% to 60%. Increasing filter efficiencies above approximately ASHRAE Dust Spot 65% (MERV 11) does not significantly reduce predicted indoor concentrations of these allergens. For environmental tobacco smoke particles and outdoor fine mode particles, calculations indicate that relatively large, e.g., 80%, decreases in indoor concentrations are attainable with practical filter efficiencies. Increasing the filter efficiency above ASHRAE Dust Spot 85% (MERV 13) results in only modest incremental decreases in concentrations. Energy costs and total costs do not always increase for higher efficiency filters. Total estimated filtration costs of $0.70 to $1.80 per person per month are insignificant relative to salaries, rent, or health insurance costs.