I am using OS to model an office building with EP. I have problems interpretating the results linked to the infiltration. I use the design flow rate method for infiltration. The design flow rate model is flow/exterior wall area. My building model is devided into 4 zones. One zone faces the south (TZ1) and one the north (TZ2) orientation, one represents the core (TZ3) and one represents the unconditioned shafts (see picture bellow).

In the Outdoor air summary results, the infiltraion rate for the core zone (TZ3) is zero, which is logical based on the design flow rate model (picture bellow)

The illogical part here is when in check the sensible heat gain summary. Here the infiltration heat addition and removal for the core zone is much larger then for the "exterior" zones.

Has anybody got an explanation for this?