Air Changes Calculator Formula

Understand the math behind the air changes calculator. Each variable explained with a worked example.

Use the Air Changes Calculator

Formulas Used

Room Volume

room_volume = volume

Required Airflow

airflow_m3h = volume * ach

Required Airflow

airflow_lps = volume * ach / 3.6

Variables

VariableDescriptionDefault
room_lengthRoom Length(m)10
room_widthRoom Width(m)6
room_heightRoom Height(m)3
achAir Changes per Hour(ACH)6
volumeDerived value= room_length * room_width * room_heightcalculated

How It Works

Air Changes per Hour (ACH)

ACH defines how many times the entire room volume of air is replaced per hour.

Formula

Airflow = Room Volume x ACH

Required ACH depends on the room function. Adequate ventilation controls temperature, humidity, odours, and airborne contaminants.

Worked Example

A 10m x 6m x 3m room requiring 6 air changes per hour.

room_length = 10room_width = 6room_height = 3ach = 6
  1. 01Volume = 10 x 6 x 3 = 180 m^3
  2. 02Airflow = 180 x 6 = 1080 m^3/h
  3. 03Airflow = 1080 / 3.6 = 300 L/s

Ready to run the numbers?

Open Air Changes Calculator