I am using Hevacomp Simulator to calculate temperature frequencies for classrooms. The classrooms are mechanically ventilated at a fresh air rate equivalent to 2 air changes/hour. Accordingly I have ticked the box for 'Additional Fresh Air' and entered a rate of 2. Do I have to somewhere select the plant operation profile, as I can't seem to find a place to do this? The profile that I want to use is (3)08:00 - 18:00.