Required CFM
Cubic Feet per Minute
What is CFM?
CFM (Cubic Feet per Minute) measures the volume of air moved by a fan or ventilation system each minute. It's the standard unit for quantifying airflow in HVAC and ventilation systems.
Proper CFM ensures adequate air circulation, removes indoor pollutants, and maintains healthy indoor air quality. The required CFM depends on room volume and how quickly you want to refresh the air (air changes per hour).
Air Changes by Room Type
Low traffic, sleeping area
Regular family activity
Cooking odors, moisture
High humidity control
May have moisture issues
Vehicle emissions
How to Calculate CFM
CFM = (Volume × ACH) ÷ 60Length × Width × Height
How often air refreshes
Hours to minutes
Tips for Proper Ventilation
Match System Size
Undersized systems can't adequately ventilate. Oversized wastes energy and money.
Consider Heat Recovery
Energy recovery ventilators (ERVs) reduce heating/cooling costs while providing fresh air.
Balance the System
Ensure proper airflow to all rooms. Blocked vents reduce effectiveness.
Filter Maintenance
Clean or replace filters regularly. Clogged filters reduce airflow significantly.
Quick Reference: CFM Terminology
CFM
Cubic Feet per Minute - air volume flow rate
ACH
Air Changes per Hour - how often air is replaced
L/s
Liters per second - metric air flow unit
ERV
Energy Recovery Ventilator
SCFM
Standard CFM - at standard conditions
Static Pressure
Air resistance in ductwork