A few notes about my model in particular:

• I currently have the design specification outdoor air rate set to 20 cfm/person
• The HVAC system shuts down entirely overnight and on weekends
• Occupancy significantly drops, but is not always at 0 when the HVAC system is off (so hours with system on and occupied hours are not exactly one to one).
• I'm assuming that (by default) if the HVAC system is off, OpenStudio knows not to supply outdoor air(?)

Both the avg. and min. values are reasonably close to the singular value I had calculated, by hand, for each of the zones' ventilation rate (for example, for the second row I had previously calculated 7.17 ACH).

Thanks!