The use of occupancy as a surrogate for particle concentrations in recirculating, zoned cleanrooms

The substantial energy demands of today's cleanroom environmental-maintenance systems provide large opportunities for energy conservation. However, cleanroom environments are subject to much more stringent standards and operate with much smaller tolerances, and therefore simple application of industrial/commercial controls is not sufficient. We conducted a set of measurements in a Class 1000 cleanroom to confirm that humans are the predominant source of particles in a cleanroom, supporting that occupancy can be used as an effective surrogate for particle concentrations. Our data suggest that people release approximately 1.7 × 104 particles per minute into the cleanroom and raise the local concentration of particles by 1742 ± 481 particles m−3 person−1. Furthermore, our timescale analysis on control system and ventilation unit responses indicates that a predictive-occupancy system is required for implementing demand-controlled ventilation.

► We demonstrated that humans are the predominant source of particles in a cleanroom.
► Occupancy is shown to be an effective surrogate for particle concentrations.
► We derived a rate of ∼1.7 × 104 particles per minute per person into the cleanroom.