DOAS system VS. Baseline

asked 2019-09-10 17:37:30 -0600

EnergyPlus question
269 ●11

updated 2020-01-19 12:10:03 -0600

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

If I have a DOAS for the proposed model, how should I model it in the baseline model? For example, if the main air system for the baseline model is system 6 (Code here is ASHRAE-2013). Should I model the DOAS for the baseline model? If not, should I add a preheat coil with the same control manner as the DOAS system of the proposed model? Should I keep the outside air fan and the exhaust air fan for the baseline model since they are in the proposed DOAS system?

Can we treat the DOAS as a fan, a cooling coil and a heating coil have been added in the outside air duct? From 1.G3.1.2.4 the baseline model should have the preheat coil modeled in the same manner as the proposed model. (that is why I asked if the preheat coil of DOAS needs to be modeled in the baseline model). 2. G3.1.2.5 mentions the return air fan, exhaust air fan for the baseline model, which makes me question about if the outside air fan from the DOAS system needs to be added to the baseline model as well.

answered 2019-09-10 19:26:25 -0600

mdahlhausen

9499 ●19 ●11 http://openstudio.net/

From ASHRAE 90.1-2013 Appendix G:

"The HVAC system(s) in the baseline building design shall be of the type and description specified in Section G3.1.1, shall meet the general HVAC system requirements specified in Section G3.1.2, and shall meet any system-specific requirements in Section G3.1.3 that are applicable to the baseline HVAC system type(s)."

So no, you should not model a DOAS in the baseline building. You should use the appropriate system from Table G3.1.1-3.

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Thank you for replying to me. But I am still confused. Can we treat the DOAS as a fan, a cooling coil and a heating coil have been added in the outside air duct? From 1.G3.1.2.4 mentioned the baseline model should have the preheat coil modeled in the same manner as the proposed model. (that is the reason I asked if the preheat coil of DOAS needs to be modeled in the baseline model). 2. G3.1.2.5 mentioned the return air fan, exhaust air fan for the baseline model, which makes me question about if the outside air fan from the DOAS system needs to be added to the baseline model as well.

EnergyPlus question ( 2019-09-11 09:29:57 -0600 )edit

For purposes of comparison, is what you are referring to as the pre-heat coil the only heating coil in the DOAS? If so, then no, you don't model that in the baseline. It's the main heating coil and is analogous to the main heating coil in your baseline system. Same for the exhaust fan for the DOAS system. Still model zone exhaust fans for kitchens, etc.