The Price of Cutting Corners: When Air Changes Went Wrong
- Admin Biz
- Oct 22
- 2 min read
The Situation: Cost Savings vs. Contamination Control
It began with a simple proposal: reduce the air changes per hour (ACH) to save on HEPA filter replacements and HVAC energy costs.
On paper, the idea seemed harmless. After all, particulate levels were always well below alert limits. The facilities team argued that fewer air changes would extend filter life and reduce maintenance downtime. Finance agreed. The potential savings were in the tens of thousands per year.
So, the cleanroom air change rate was lowered from 40 ACH to 20 ACH.
Everything seemed fine… for a while.
The Warning Signs
Over the next few months, operators started noticing subtle shifts.
Settling plates that used to stay spotless began showing occasional colonies.
Compressed air lines tested “clean” one week and “borderline” the next.
Environmental monitoring results showed trending particle counts , but not yet excursions, but definitely creeping upward.
Then, one day, a critical batch failed microbial release testing.
The Investigation
The initial response was to blame personnel practices or cleaning agents. But environmental trending told another story.
With fewer air changes, the cleanroom’s recovery rate — how quickly it returned to classified conditions after door openings — had dropped dramatically. The once-robust unidirectional flow had weakened. Viable particles lingered longer, especially near equipment and low-flow corners.
In short, the system’s contamination control envelope had collapsed.
The cost savings from HEPA filters were quickly eclipsed by:
⛔️Lost product batches
⛔️Unplanned shutdowns
⛔️Decontamination and requalification efforts
⛔️And the inevitable reinspection by regulators
The Root Cause
The change control documentation had been approved without a formal risk assessment or airflow visualization study.
What was missing wasn’t a filter --- it was the science.
No one had modeled how airflow velocity and turbulence would change with reduced ACH. The assumption was: “If counts are low, we’re safe.” But counts are lagging indicators. The damage was done long before the data reflected it.
The Real Cost
In the end, the “savings” project cost the company over $2 million in lost product and downtime. The facility reverted to its original air change rates, but the trust between departments: Quality, Engineering, and Operations, took far longer to rebuild.
The Takeaway: Cost Control Requires Process Understanding
Energy efficiency is a worthy goal, but never at the expense of contamination control.
At F2i Partners, we teach that validation isn’t about defending what you did. It’s about proving why you did it.
Changes to systems that impact airflow, pressure cascades, or cleanroom recovery should always be backed by:
✅ Airflow visualization (smoke studies)
✅ Risk-based impact assessment
✅ Trending analysis of viable and non-viable data before and after the change
Because what you can’t see in the air… can destroy everything you built on the ground.
---
“Cleanroom control is like trust. It takes years to build, seconds to lose, and a fortune to restore.”
Comments