Restoration Cert Lab · Free practical tool

Airflow and ACH calculator

Relate a documented enclosure airflow to volume during a restoration exercise. Nominal air changes do not specify the number of air movers or establish containment performance.

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The method

ACH = Q × 3600 / room volume; nominal interval = volume/Q.

Before using the result

  • Nominal air changes assume a well-mixed enclosure. ACH is not effective contaminant removal, drying performance or a prescribed equipment count.

Worked examples

These original training examples illustrate the method for IICRC Water Restoration Technician (WRT). Use the matching “Load example” button above to explore a variation; example values are not equipment settings or prescribed criteria.

1. Worked example

Relate a documented enclosure airflow to volume during a restoration exercise. Nominal air changes do not specify the number of air movers or establish containment performance.

Room volume input
Dimensions
Room length
5 m
Room width
4 m
Room height
3 m
Measured air volume flow
360 m³/h
  1. Room volume = 60 m³.
  2. ACH = 0.1 × 3600 / 60.
  3. Interval = 60 / 0.1 seconds.
  • Room volume: 60 m³
  • Air changes: 6 h⁻¹
  • Nominal interval: 600 s

2. Comparison example

Compare a different supplied condition using the same method. For Restoration Cert Lab, the important check is that the input meaning, units and method assumptions still match the problem.

Room volume input
Dimensions
Room length
5 m
Room width
4 m
Room height
3 m
Measured air volume flow
720 m³/h
  1. Room volume = 60 m³.
  2. ACH = 0.2 × 3600 / 60.
  3. Interval = 60 / 0.2 seconds.
  • Room volume: 60 m³
  • Air changes: 12 h⁻¹
  • Nominal interval: 300 s

Check your understanding

1. Which relationship is used?

ACH = Q × 3600 / room volume; nominal interval = volume/Q.

2. Which assumption should you check first?

Nominal air changes assume a well-mixed enclosure. ACH is not effective contaminant removal, drying performance or a prescribed equipment count.

3. How should you verify a different unit system?

Convert every input to the displayed calculation units first. Equivalent physical inputs must give equivalent results; a unit label alone does not convert a number.

Continue with the matching exam topic

This tool connects to IICRC Water Restoration Technician (WRT) free practice. Work through a question independently, then use the calculation steps to identify where your method differs. The tool stays free whether or not you choose paid preparation.

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