Facility Cert Exam · Free practical tool

Room airflow calculator

Convert a documented facility design ACH target into a flow requirement. The calculation makes the target visible without claiming it satisfies an occupancy-specific ventilation standard.

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The method

Required flow = room volume × target ACH / 3600.

Before using the result

  • Target ACH must be selected independently for the actual use. This calculation does not establish compliance with an occupancy-specific ventilation standard.

Worked examples

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

1. Worked example

Convert a documented facility design ACH target into a flow requirement. The calculation makes the target visible without claiming it satisfies an occupancy-specific ventilation standard.

Room length
10 m
Room width
8 m
Room height
3 m
User-supplied target ACH (h⁻¹)
6
Source of target
Worked example only; enter the applicable design target
  1. Volume = 240 m³.
  2. Flow = 240 × 6 / 3600 m³/s.
  • Volume: 240 m³
  • Calculated flow: 0.4 m³/s
  • Target source: Worked example only; enter the applicable design target

2. Comparison example

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

Room length
10 m
Room width
8 m
Room height
3 m
User-supplied target ACH (h⁻¹)
4
Source of target
Worked example only; enter the applicable design target
  1. Volume = 240 m³.
  2. Flow = 240 × 4 / 3600 m³/s.
  • Volume: 240 m³
  • Calculated flow: 0.2666667 m³/s
  • Target source: Worked example only; enter the applicable design target

Check your understanding

1. Which relationship is used?

Required flow = room volume × target ACH / 3600.

2. Which assumption should you check first?

Target ACH must be selected independently for the actual use. This calculation does not establish compliance with an occupancy-specific ventilation standard.

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 BOMI Systems Maintenance Technician (SMT) 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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