Air changes per hour, often shortened to ACH, describes an estimated number of room volumes passing through a device in an hour.

Room volume comes from floor area multiplied by ceiling height. That gives the planner more context than floor area alone.

The selected mode affects the example airflow value used in the calculation. The planner then compares that estimate with the room volume.

The result helps compare a device and mode for your plan. It is an example calculation, not a reading from your home.

Add multiple rooms to compare their dimensions. The planner also shows a filter plan and yearly cost based on listed refill prices.