A method includes setting a desired cleaning time and desired air changes. A volume of a controlled space is determined. A total clean air volume to be delivered to the controlled space is determined based on the volume and the desired air changes. (a) A remaining clean air volume to be delivered to the controlled space is determined. (b) A remaining cleaning time is determined. (c) In response to determining that a ventilation unit is not present: a recirculated air flow rate is determined based on the remaining clean air volume and the remaining cleaning time, a blower flow rate is set to the determined recirculated air flow rate, the method waits for an idle time, and a delivered clean air volume already delivered to the controlled space is determined. Operations (a), (b), and (c) are repeated until the total clean air volume is delivered to the controlled space.