How do I calculate air movement?

Calculating air movement typically involves measuring airflow rate, velocity, and air changes per hour depending on your goal. For simple ventilation, airflow rate is calculated as volume of air moved per time, often expressed in cubic feet per minute CFM or cubic meters per hour. You can calculate CFM as velocity times cross-sectional area, for example air velocity measured in feet per minute multiplied by duct area in square feet gives CFM. Air changes per hour ACH is calculated as airflow rate multiplied by 60 minutes divided by room volume, which tells how many times air in a room is replaced per hour. To measure velocity, you can use an anemometer held in the airstream. For natural ventilation, factors include wind speed, opening size, and temperature differences. In HVAC, calculations also consider pressure drop and fan curves. For drying or industrial processes, you may calculate mass transfer of moisture using psychrometrics. Accurate calculation often requires instruments like anemometers, manometers, and hygrometers, and for complex systems consulting engineering guidelines or using software tools helps ensure proper airflow for comfort, drying efficiency, and indoor air quality.