Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
OK, so I do not know if this counts as a proper answer, but I am getting plausible figures now. Basically, at first I thought I had too much infiltration and/or too much outdoor air in a very humid climate, so that nighttime relative humidity in the zones came out to be very high (100% during many nights). So I implemented Molly Curtz' recommendations from above (Maximum Fraction of Outdoor Air Schedule and 0.04 cfm/ft2 at 25%/100% infiltration schedule). However, this only resulted in minor improvements of the situation.
As it turns out, I also have two restrooms on each of my floors. I had given each a zone exhaust fan at 400 cfm and had left the Balanced Exhaust Fraction Schedule Name for each fan empty. I cannot claim I understand the balance concept, but this had evidently and in a very reproducible way led to the restrooms having extremely low relative humidity and the other spaces having extremely high relative humidity. Simply selecting the Always On Discrete schedule for Balanced Exhaust Fraction Schedule Name seems to have now resolved these implausible results.
I know this is the monkey pushing the keys on the typewriter, without real understanding, but I thought this description of symptoms and their cure might help other people. Perhaps there is someone out there who can truly explain how this exhaust fan balancing phenomenon would have led to the observed results, though.
