[BLDG-SIM] What does ADJUST-LOADS adjust?

[Fred Porter]

All;
When simulating (eQ v3-61, DOE-2.2 v44e4) a building with a "plenum"
(unconditioned or plenum), and changing the roof absorptance greatly,
the auto-sized design air flow does NOT seem to change in the zone
below, even though the ZONE SIZING-OPTION = ADJUST-LOADS. After
observing this in a big model, I tested this in a simple single zone
model (eQ Wiz). I made sure airflow sizing was driven by cooling loads,
and created a parametric run that changed the ABSORPTANCE of the roof
construction between 90% and 10%. Hourly cooling loads vary as expected,
but design airflow remains the same between both models.

Raising the DESIGN-COOL-T (from the default 75F, same for all zones) in
the "plenum" increases the design airflow in the zone below (for both
absorptances), but I thought ADJUST-LOADS did more than just recognize
this input. The problem seems to persist whether I have a cooling design
day or not, and whatever I do with the LOADS SPACE "TEMPERATUREs" and
ZONE DESIGN-COOL-Ts. 

Any insights out there? Anyone else notice this behavior? Is this a bug,
or did I expect too much of the program? Unless the DESIGN-COOL-T is
raised (to a value one must estimate or find by inspection of hourly
reports), it appears the program under-sizes airflow to zones where a
significant fraction of the heat gain is through a ceiling
cavity/plenum/attic, or I suppose any "un-conditioned" buffer space.

Fred Porter




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