Ventilation and air change calculators
Air-change, heat-removal and extraction calculations for plant and safety engineers. Confirm the design basis and site controls separately.
Method & worked example
Convert air changes per hour to airflow
Airflow in m³/h equals room volume in m³ multiplied by air changes per hour (ACH). Selecting an appropriate rate is a separate design task.
| Step | Calculation | Result |
|---|---|---|
| Room volume | 10 m × 6 m × 3 m | 180 m³ |
| Assumed air-change rate | 6 per hour, for arithmetic only | 6 ACH |
| Airflow | 180 × 6 | 1,080 m³/h |
| Flow conversion | 1,080 / 3.6 | 300 L/s |
What this result does not establish
This volume calculation does not model a gas release, exposure level, heat load, air distribution or the time needed to clear a hazardous atmosphere. Fan selection also needs duct and fitting resistance, discharge conditions and the installed operating point.
Ventilation alone does not authorise entry into a confined space. Isolation, atmospheric assessment, monitoring and emergency arrangements need competent planning for the actual space. See Safe Work Australia's confined-spaces guidance.
Match the tool to the duty
Choose plant-room ventilation for equipment heat, enclosure cooling for switchboards, or the appropriate gas-room or purge calculation for a specialist assessment. These duties are not interchangeable merely because all report airflow.
Static educational example · Updated 1 October 2026 · Methods and limitations. Project calculations run in the subscription application; New accounts require approval.
Why it matters on the job
State the air-change basis
Record the selected method, hazard assumptions and applicable project requirements.
Assess the release conditions
A room-volume calculation alone cannot demonstrate that a gas release stays below exposure limits.
Fans that deliver
Check airflow at the installed resistance and assess intake and discharge locations.
9 Ventilation & Safety calculators
Every calculator in this category, by its reference code. Running them requires an approved Tenselo account with access to the relevant calculators.
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HVC-001 Hydronic Heating Design Calculator
Heat load, underfloor circuits / radiators / fan-coils, pump flow & head, heat-pump / boiler size, buffer tank and running cost (AU, location-driven)
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HVC-002 Reverse Cycle Air Conditioner Sizing
Split / ducted / shed / container / commercial cooling + heating load from location design temps, insulation, glazing & orientation -> recommended kW + running cost
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SAF-001 Battery Room Hydrogen Ventilation
Ventilation airflow & natural vent opening to keep H2 below 4% (IEC 62485-2 / EN 50272-2)
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SAF-002 Confined Space / Wet-Well Purge
Pre-entry purge time and continuous air changes for a tank / wet well from the blower airflow (AS 2865)
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SAF-003 Diesel Engine-Room Ventilation
Combustion air + radiated-heat + radiator airflow for a diesel pump/genset room (screening - confirm with the engine data)
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SAF-004 Gas / Chlorine Room Ventilation
Extraction fan airflow for a gas store/dosing room from volume x air changes (AS 2927 / plant-room practice)
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SAF-005 Pump / Plant-Room Ventilation
Extraction airflow to remove motor/engine heat and hold a room temperature rise, plus minimum air changes
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SAF-006 Safety Shower / Eyewash (AS 4775)
Required flow, 15-minute water volume and supply pipe size for emergency showers & eyewashes (AS 4775 / ANSI Z358.1)
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SAF-007 Switchboard / Enclosure Cooling
Multi-component heat load + location ambient (hot shed / sun) -> natural vent, fan (m3/h) or AC (kW) (Rittal / NHP / Phoenix, IEC 60890)
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