I have a proposed 100,000 square foot school in Chicago that I'm
modeling with eQuest, when I have no 'Night Cycle Fan Control' on the
main VAV air-handling systems (NIGHT-CYCLE-CTRL = Stay Off), my annual
energy expense for the building is around $62,000. When I turn 'Night
Cycle Fan Control' on (NIGHT-CYCLE-CTRL = Cycle on Any), the annual
value goes up to $96,000 (mostly natural gas consumption, with some
electric consumption due to fan power). I'm convinced that during the
Night Cycle Fan Control that the VAV systems are bringing in Outside
Air, which is making the energy go way up. Which report will show me if
I am guessing right about the outside air? And, how can I change the
'Night Cycle Fan Control' outside air availability to NOT include at
night?? So that at night, the OA dampers are shut and it's just doing a
re-circ/reheat scenario...
Thanks!
Josh Greenfield, PE, LEED AP
Josh,
You need to create a "Minimum Air Schedule" for the outside air damper. The
schedule type needs to be "Frac/Design" and it should have values of "0" when
you want the outside air damper closed, and "-999" when you want to return to
normal operation and use the calculated OSA value. You assign it under the
"Outside Air and Economizer" tab you have shown below. You can check this by
setting up an hourly report for the HVAC system and trending the OSA
fraction.
Jay Keazer, EI