Cleanroom & Contamination Control worked example

Cleanroom Air Changes at 110% share of room volume served by this air-change scenario: a worked example

Push share of room volume served by this air-change scenario up to 110% and the picture changes. This example computes every intermediate figure at that operating point. a team needs to check whether fan, HEPA, and HVAC capacity align with the target cleanroom class for a room or cleanroom zone

The inputs for this scenario

  • Cleanroom room volume: 18,000 ft³ (unchanged)
  • Target air changes per hour: 45 ACH (unchanged)
  • Share of room volume served by this air-change scenario: 110 % (raised for this scenario; the documented default is 100)
  • Fixed makeup-air or leakage allowance: 2,500 ft³/h (unchanged)

Working through the calculation

  • Applying the documented formula (Recirculated air-change load = cleanroom room volume × target air changes per hour × room volume served by this air-change scenario) to the inputs above produces each figure below.
  • At this operating point the engine returns 893,500 cleanroom air-change airflow load for cleanroom air-change airflow load, the number this scenario is built around.
  • At this operating point the engine returns 49.64 $ / piece for air-change load per room ft³.
  • At this operating point the engine returns 891,000 $ for recirculated air-change load.
  • At this operating point the engine returns 2,500 $ for fixed makeup-air or leakage allowance.

How this compares with the baseline

  • Against the tool's baseline example, where share of room volume served by this air-change scenario sits at 100% and the headline result is 812,500 cleanroom air-change airflow load, this scenario comes in 9.97% above the baseline at 893,500 cleanroom air-change airflow load.
  • It computes the total air-change airflow load by combining recirculated airflow needed for the target ACH with a fixed makeup-air or leakage allowance. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Cleanroom air-change airflow load: 893,500 cleanroom air-change airflow load (headline result)
  • Air-change load per room ft³: 49.64 $ / piece
  • Recirculated air-change load: 891,000 $
  • Fixed makeup-air or leakage allowance: 2,500 $

Run it with your numbers

  • Every input above is editable in the live Cleanroom Air Changes calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.