A:Answer Hi, this is Summer with Dyson. The filter will need to be replaced once a year if the machine is ran for 12 hours a day. If you run it for 24 hours a day, it is about every 6 months. There is also an auto mode that you can set it on when you need to and it will be like a stand by mode and clean the air as needed to help the filter life as well.
Best wishes,
Summer
Dyson Customer Support