Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

• the most efficient way to navigate the Engineering ToolBox!

# Air Change Rate

## Calculate air change rates - equations in imperial and SI units.

### Air Change Rate - Imperial Units

Air change rate - air changes per hour - expressed in imperial Units

n = 60 q / V                                  (1)

where

n = air changes per hour (1/h)

q = fresh air (make up air) flow through the room (Cubic Feet per Minute,  cfm)

V = volume of the room (Cubic Feet)

### Air Change Rate - SI Units

Air change rate expressed in SI-units

n = 3600 q / V                             (2)

where

n = air changes per hour

q = fresh air (make up air) flow through the room (m3/s)

V = volume of the room (m3)

### Example - Air Change Rate SI Units

With an air flow of 3 m3/s in a 20000 m3 room the air change rate can be calculated as

n = 3600 (3 m3/s) / (20000 m3)

= 0.54 (h-1)

### Typical Air Changes per Hour

Typical air changes per hour for well-insulated spaces:

• no windows or exterior doors - 0.33 (1/h)
• windows or exterior doors on one side - 0.67 (1/h)
• windows or exterior doors on two sides - 1 (1/h)
• window or exterior doors on three sides - 1.33 (1/h)

## Related Topics

• Ventilation - Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.

## Search Engineering ToolBox

• the most efficient way to navigate the Engineering ToolBox!

## SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

## Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

## Unit Converters

Temperature

oC
oF

Length

m
km
in
ft
yards
miles
naut miles

Area

m2
km2
in2
ft2
miles2
acres

Volume

m3
liters
in3
ft3
us gal

Weight

kgf
N
lbf

Velocity

m/s
km/h
ft/min
ft/s
mph
knots

Pressure

Pa (N/m2)
bar
mm H2O
kg/cm2
psi
inches H2O

Flow

m3/s
m3/h
US gpm
cfm

6 24

This website use cookies. By continuing to browse you are agreeing to our use of cookies! Learn more