Air Change Rate
Calculate air change rates - equations in imperial and SI units.
Sponsored Links
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)
Sponsored Links
Related Topics
-
Ventilation
Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.
Related Documents
-
Air Change Rates in typical Rooms and Buildings
Fresh air (make up air) rquirements - or recommended air change rates (ACH) for typical rooms and buildings like auditoriums, kitchens, churches and more. -
Garage Ventilation
Exhaust ventilation from garages and workshops. -
Outdoor Supply Air Rates
Recommended supply air rates of outdoor air - with or without smoking - in rooms like banks, assembly halls, hotels and many more.
