TOOL GUIDE
Ventilation & outdoor airflow
Calculate ventilation by occupancy, area, ACH or combined occupancy + area/Ez.
Purpose & scope
Calculate ventilation by occupancy, area, ACH or combined occupancy + area/Ez.
Zone/space calculation; excludes multizone system ventilation efficiency, specific contaminants and leakage. Selecting ASHRAE does not load standard table rates.
Inputs
Use drawings, design conditions and manufacturer data. Units and example values follow the calculator; example values are not universal design requirements.
| Parameter | Value / interpretation |
|---|---|
| Calculation method | Only the selected calculation method determines the resulting airflow. |
| Design basis (enter rates below) | Project requirements / example inputs / ASHRAE 62.1 — enter rates for the applicable edition / Other standard — enter specified rates |
| Room floor area · m² | Floor area used for area-based ventilation or room volume. |
| Room height · m | Clear room height used for room volume and ACH. |
| Design occupancy · người / people | Design occupancy, based on the intended use of the space. |
| Outdoor rate per person (combined) · L/(s·person) | Outdoor-air rate per person in the combined method. |
| Outdoor rate per area (combined) · L/(s·m²) | Outdoor-air rate per floor area in the combined method. |
| Air distribution configuration (Ez) | Custom / no configuration selected / Cool ceiling supply · Ez = 1 / Warm ceiling supply, low return · Ez = 1 / Warm ceiling supply, high return — ΔT ≥ 8°C · Ez = 0.8 / Warm ceiling supply, high return — weak jet · Ez = 0.8 / Warm ceiling supply, high return — adequate throw · Ez = 1 / Low cool supply, high return — mixed · Ez = 1 / Low warm supply, low return · Ez = 1 / Low warm supply, high return · Ez = 0.7 |
| Zone air distribution effectiveness | Choose a configuration or enter the design Ez. Used only by the combined people + area method. |
| Air changes per hour · lần/giờ · h⁻¹ | Air changes per hour multiplied by room volume. |
| Standalone per-person rate · L/(s·person) | Standalone rate for the per-person method. |
| Standalone per-area rate · L/(s·m²) | Standalone rate for the per-area method. |
Steps
- Select the method and design basis; replace example rates with applicable occupancy/standard values.
- Enter floor area, height, occupancy and applicable rates. For combined calculations check Ez configuration.
- Read the selected method’s flow; transfer to ducts or outlets as needed.
Worked example
This reproducible training example uses the values below. Select the appropriate mode and overwrite restored project values. Example rates, K values and equipment losses are assumptions, not mandatory design criteria.
Examples use a decimal point and no thousands separator.
All example inputs
| Parameter | Value / interpretation |
|---|---|
| Calculation method | People + area / distribution effectiveness |
| Design basis (enter rates below) | Project requirements / example inputs |
| Room floor area | 100 m² |
| Room height | 3 m |
| Design occupancy | 10 người / people |
| Outdoor rate per person (combined) | 2.5 L/(s·person) |
| Outdoor rate per area (combined) | 0.3 L/(s·m²) |
| Air distribution configuration (Ez) | Custom / no configuration selected |
| Zone air distribution effectiveness | 1 |
| Air changes per hour | 6 lần/giờ · h⁻¹ |
| Standalone per-person rate | 10 L/(s·person) |
| Standalone per-area rate | 1 L/(s·m²) |
Expected results (rounded)
| Parameter | Value / interpretation |
|---|---|
| Selected-method airflow | 198 m³/h |
| Equivalent ACH | 0.66 h⁻¹ |
Small differences in displayed rounding are normal. A result that passes the entered limits does not establish suitability for the complete system.
Method & limitations
Zone/space calculation; excludes multizone system ventilation efficiency, specific contaminants and leakage. Selecting ASHRAE does not load standard table rates.
Default rates are entry examples, not requirements for every occupancy. Enter rates from the occupancy, standard and edition applicable to the project.
Combined method: Vbz = Rp·P + Ra·A; Voz = Vbz/Ez. Air-change method: V = A·h·ACH. The four methods are separate alternatives, not automatically summed or maximized.
The combined result is single-zone outdoor air only. Multizone system efficiency, population diversity, demand control and edition-specific density adjustments are excluded. Not a smoke extraction or stair pressurization calculation.
Common mistakes
Adding independent method results; treating example rates as mandatory; omitting Ez in the combined method.
Projects & reports
- Choose or create an engineering project and enter your actual design inputs.
- Project inputs/results are autosaved in this browser. Where a saved-list panel is available, name and add the selected section or alternative to compare multiple options.
- Review the report before exporting PDF. In the print dialog select Save as PDF. Export JSON for backup and use Open file to restore it; PDF cannot restore project data.
Saved results do not automatically recalculate when another tool changes. Review any dependency warning, recalculate and update the affected results.
References & related tools
ASHRAE — Ventilation and Infiltration
The tool implements the methods and limits stated above; linking a standard does not establish complete compliance with that standard.