This document discusses air filtration as an energy conservation measure. It summarizes that dynamic air cleaners can significantly reduce sub-micron particles, pathogens, and VOCs while reducing energy consumption and maintenance costs compared to high efficiency passive filters. A case study shows that replacing filters with dynamic air cleaners resulted in over 57,000 kWh in annual energy savings and a payback period of less than 2.2 years. Dynamic air cleaners are recommended for applications using high efficiency filters or in buildings with high occupant densities.