Hi eQuest Group,
I was wondering if there is a quick way to determine how much of the projected energy use in a building is due to conditioning of ventilation air? I have scoured through the eQuest reports and detailed simulation output but no luck (unless I?m missing something). I suppose I can run the simulation again with ventilation set to zero, but it would be great if it could be drawn straight from the simulation output.
Thanks!
Dave
David R. Weigel, PE
Hi Dave, I use the quick and dirty way for peak vent loads from the SV-A
report using the multiplier of the supply cfm and the OA% values at the top
of the report. You can also compare the peak Vent CFM at the zone level at
the bottom of the report where they show the OA CFM for each zone.
Does anybody else use hourly reports to compile the Ventilation data?
Pasha
I don't think there is a direct way to do this. Could you just run it with zero outside air and see the difference?
Another way I guess would be to subtract the space loads from the system loads - which would in theory get you the ventilation loads. This won't actually tell you how much energy is being used to meet that load though. Much simpler to zero out the OA.
Vikram Sami
As long as you are careful to allow for economizer operation, this might give you a good sense of the energy load from OA intake.
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Daniel Knapp, PhD, P Phys, LEED? AP O+M
This is something I've been trying to figure out myself and I think there is a direct way to do. I haven't tried this, but one ought to be able to calculate the hourly load due to OA at the system level by printing out hourly reports of the supply air temperature and humidity, the return air temperature and humidity, the outdoor air temperature and humidity and the outdoor air fraction, the heating coil load and the cooling coil load. From these values, the enthalpy of the three air streams can be calculated and the hourly load due to OA on the coils can be calculated. It might be a little tricky to sort out the psychometrics, but it should be doable.
Cheers,
Dan
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Daniel Knapp, PhD, P Phys, LEED? AP O+M
Thank you all --
Dan, that's a great idea. I'll share the enthalpy calculation when I get it
smoothed out.
Best to you,
Dave
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