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Modeling Optional Ventilation Fan

asked 2014-10-27 17:24:26 -0500

AB's avatar

updated 2014-10-27 18:23:16 -0500

While doing simulation for a system that has an optional ventilation fan, should we model the fan in the baseline as well. ASHRAE appendix G does not say anything about modeling this fan and nor does it have any guidance on allowance for fan power. In that case, should the ventilation fan be modeled same in baseline as in proposed? And if we are not supposed to model the OA fan at all in the baseline design, should we add the static pressure of the outside fan to the static pressure for the primary fan for baseline to get a realistic calculation of fan power?

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answered 2014-10-28 08:37:15 -0500

I would say that if you are modelling the fan in the proposed case you should take account of it in the baseline case. If the fan has outdoor air coming in, I would either add this quantity of outdoor air to the overall AHU and put it through the baseline system that way. If there is only the fan in this room then I would model system 3 or system 4 in this space specifying the outdoor air that is coming through. It is a difficult question and if you have time you can send it to GBCI, they will answer with advice in about 2 - 3 weeks.

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Asked: 2014-10-27 17:24:26 -0500

Seen: 190 times

Last updated: Oct 28 '14