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From airflow to face area.
Explore an AHU face area and the fan power implied by your pressure and efficiency assumptions. Results describe one air stream at one operating point.
Your assumptions
Calculated estimates
- Required airflow face area
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- Equivalent square face, before casing allowances
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- Total pressure assumption
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- Electrical power per airflow, including external pressure
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- Fan electrical power for this air stream
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Illustrative calculations for early discussion. Dimensions exclude casing, frames and service clearances. The power estimate does not select a fan or determine regulatory SFP, Eurovent class, ErP conformity or certification. Final selections require component data and engineering review.
How the estimates work
Airflow and face velocity determine the required clear face area. A square face is shown as a geometric reference; a real component can have a different aspect ratio.
Face area = airflow ÷ 3600 ÷ face velocity
Square face side = √face area
For the power estimate, add internal and external pressure losses and divide by the combined efficiency expressed as a fraction. Multiply by airflow in m³/s to estimate the electrical input for one air stream.
Power per airflow = (internal pressure + external pressure) ÷ efficiency
Fan electrical power = power per airflow × airflow ÷ 3600
Pressure, efficiency and geometry must use consistent reference conditions. Return or extract fans need their own calculation. Changing face area here does not automatically recalculate component losses or fan efficiency.
Continue with a project review
AirSelect3D provides a browser-based 3D AHU workflow with component integrations and PDF/DXF output. Tell us your unit range, suppliers and documentation requirements to discuss a demonstration and a quotation.