WHITEPAPER - Design Driven by Sources

Cleanroom design has relied on the same fixed table for decades: a set number of air changes per hour for ISO 8, more for ISO 7, more still for ISO 6. These numbers feel familiar and safe, but they describe an outcome, not a cause. A cleanroom is clean because the supply of clean air outpaces the contamination generated inside it, not because a certain volume of air has passed through.

The scientific literature is unambiguous about where that contamination comes from. In an occupied, non-unidirectional cleanroom, people are by far the dominant source of airborne particles, and their emission rate is not a fixed number. It’s governed by movement, occupancy and, above all, the garments worn. High-performance cleanroom clothing can reduce human particle emission by a factor of several or more.

In our whitepaper “Design Driven by Sources” we explain how to size airflow directly from that contamination source, using the established cleanroom ventilation equations, rather than from a generic ACH table. A worked example for a typical ISO 7 room shows that source-driven design reduces the required airflow by around 61% compared to a rule-of-thumb ACH of 25, and by around 84% when combined with high-performance clothing, with the corresponding savings in fan energy, capital cost and carbon footprint.

Want the full reasoning, including the calculation method and all sources? Download the whitepaper below.