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[EnergyPlus_Support] Re: Mechanical ventilation for passive dwellings
This is a bit of a mindset shift. "Every zone must have an inlet and an outlet." If air flows into a zone, it must also flow out somewhere, else the zone will pressurize till it explodes. Both inlets and outlets can be cracks, uncontroled air terminals, VAV or controlled terminals, a combination, it does not bother the air much. In e+ only one classical exhaust node is allowed. One can introduce other "outlet ports" to this "zone tank" (Dr Li's analogy) by means of the zonemixing objects or AFN. I understand the comfort criteria in the areas of the house must be modelled, hence the need to keep them splitup and not lumped. If you have approximately 10 or less zones, the AFN is a good solution.
Zonemixing objects are the easiest, but may be impossible to tie in to a complexly controlled and varying supply air flow (EMS may be required). Zonemixing objects are well suited to "join" the air volumes of to seperate zones by mixing back and forth at high mixing rates. If you have a very simple constant air supply, then it also works well. Maybe some new objects have been released in the newer versions of e+ for your kind of problem.
The last kind of problem of this sort is that users want to connect 2 or more airloops to one zone. This is (was?) not possible, with virtual zone splitting a possible work around. This is (was?) also on the devloper's list.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "gosset_serge" <gosset_serge@...> wrote:
>
> In accordance to passive house and belgian standards, the mechanical ventilation is done as follows:
> - a MV group with heat exchanger
> - blows the (eventually preheated) air in "dry" rooms (sleeping and living rooms, offices, ...)
> - takes it back from the "wet" or more polluted rooms (kitchen, bathrooms, storage rooms, ...)
> - in between, the air moves by various openings, hallways, staircaises, ...
>
> We often need to split those areas in several zones, meaning that some have an air inlet only while other have an outlet only.
>
> Since both flows cross each other in the heat exchanger, they have to belong to the same HVAC Airloop. The problem here is that every zone must have one inlet and one outlet. I tought using a return plenum (a zone indeed) but only one can be used in the airloop and I have several "wet" zones.
> |...
> in---| > |--supply fan--splitter|--z1--|
> | | |--z2--|--z4----|
> |HEX| |--z3--| |
> | | |
> out--| < |--return fan--mixer|------------------|
> |...
>
> The air can be moved from one zone to another using either (cross)mixing either the airflow network, I guess.
>
> Did anyone model this ? Do you have some suggestions ? Any clue ? I did not reach any efficient or fully working model yet...
>
> Thanks in advance ...
>
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