The LEED Reference Guide only addresses the increased ventilation calculation at the zone level, not the system level. I understand that the outdoor air supplied to each zone needs to be increased by 30% to obtain this credit. I found a way to do this on the 62MZ spreadsheet. What about at the system level? Vot (the amount of air the system needs to suppy, i.e. the corrected outdoor air) cannot simply be increased by 30%. It is dependent on Ev, which is dependent on the critical zone. I am finding that when I increase the outdoor air to each zone by 30%, the system outdoor air (Vot) increases by much more, as much as 55%. I am getting some units with very high outdoor air percentages. I can increase the supply air to the critical room, which increases Ev and therefore decreases Vot. But it seems arbitrary, and I am not convinced this is the correct approach. Has anyone had any experience with this?