# Ventilation Rate Calculator (People / Area / Contaminant)

Compute the required outdoor / supply ventilation rate. ASHRAE 62.1 ventilation-rate procedure: people component Vpz = Rp·P, area component Vaz = Ra·A, breathing-zone outdoor air Vbz = Vpz + Vaz, zone supply airflow Voz = Vbz / Ez. Three modes: ASHRAE 62.1 (people + area), per-person rate (P × Rp), or contaminant dilution (Q = G / (C_acc − C_sup), where G can be mg/s, mg/h, or L/s of gas and concentrations mg/m³ or ppm). Results reported in L/s, m³/h, and CFM.

> Canonical page: https://elysiatools.com/en/tools/ventilation-rate-calculator

- **Category:** Math & Numbers

- **Keywords:** ventilation rate, outdoor air, ASHRAE 62.1, ventilation rate procedure, VRP, per person, area rate, zone effectiveness, contaminant dilution, CO2, IAQ, indoor air quality

## Overview

The Ventilation Rate Calculator estimates required outdoor or supply airflow using ASHRAE 62.1 people-and-area inputs, a per-person rate, or contaminant dilution. Results are provided in L/s, m³/h, and CFM.

## Inputs

- **Mode** (select): ASHRAE 62.1 (people + area), per-person rate, or contaminant dilution.
- **Occupant Count P** (number): Number of occupants P. Used in 'ashrae' and 'perperson' modes.
- **Per-person Rate Rp** (number): Outdoor air rate per person Rp, in the selected Per-person Rate Unit. Used in 'ashrae' and 'perperson' modes.
- **Per-person Rate Unit** (select)
- **Floor Area A** (number): Floor area A, in the selected Area Unit. Used in 'ashrae' mode.
- **Area Unit** (select)
- **Area Rate Ra** (number): Outdoor air rate per unit area Ra, in the selected Area Rate Unit. Used in 'ashrae' mode.
- **Area Rate Unit** (select)
- **Zone Air Distribution Effectiveness Ez** (number): Zone air distribution effectiveness Ez (0.1–2). Default 1.0. Typical: ceiling supply cool air = 1.0, warm air = 0.8, floor supply = 1.0. Used in 'ashrae' mode.
- **Pollutant Generation Rate G** (number): Pollutant generation rate G, in the selected Pollutant Unit. Used in 'contaminant' mode. For CO₂: ~0.005 L/s per person at rest.
- **Pollutant Unit** (select)
- **Acceptable Concentration C_acc** (number): Acceptable (target) concentration C_acc, in the selected Concentration Unit. Used in 'contaminant' mode.
- **Supply Concentration C_sup** (number): Supply (outdoor) air concentration C_sup, in the selected Concentration Unit. Used in 'contaminant' mode.
- **Concentration Unit** (select)
- **Pollutant Molar Mass M (g/mol)** (number): Pollutant molar mass M (g/mol), used to convert ppm ↔ mg/m³. Default 44.01 (CO₂). Only used when Concentration Unit = ppm in contaminant mode.
- **Decimal Places** (number)

## When to use

- Estimate outdoor airflow for a room using occupant count, floor area, rate inputs, and zone air distribution effectiveness.
- Calculate ventilation from a per-person outdoor air requirement.
- Size airflow for contaminant dilution using pollutant generation and acceptable and supply concentrations.

## How it works

- Select ASHRAE 62.1, per-person rate, or contaminant dilution mode.
- Enter the inputs required for the selected mode, including units for rates, area, pollutant generation, and concentration.
- For ASHRAE mode, the calculator combines the people component Rp × P and area component Ra × A, then applies Ez to the breathing-zone airflow.
- Review the calculated airflow in L/s, m³/h, and CFM, with the selected decimal precision.

## Use cases

- Estimate outdoor air requirements for offices, classrooms, and other occupied zones using people and floor-area rates.
- Compare required airflow when a zone uses different air distribution effectiveness values.
- Evaluate airflow needed to dilute CO₂ or another pollutant from a supply concentration to an acceptable target.

## Frequently asked questions

### What ventilation modes are available?

The calculator supports ASHRAE 62.1 people plus area, per-person rate, and contaminant dilution modes.

### What does the ASHRAE 62.1 mode calculate?

It calculates Vpz = Rp × P, Vaz = Ra × A, Vbz = Vpz + Vaz, and Voz = Vbz ÷ Ez.

### Which units are supported for the result?

Results are reported in liters per second, cubic meters per hour, and cubic feet per minute.

### Can I calculate CO₂ dilution airflow?

Yes. Use contaminant mode with a CO₂ generation rate, acceptable concentration, and supply concentration. The default molar mass is 44.01 g/mol.

### Which concentration units can I enter?

Contaminant mode accepts ppm or mg/m³. Pollutant generation can be entered in L/s of gas, mg/s, or mg/h.

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