[Equest-users] Systems /Zoning question.

[pranita kothuru]

All/Nick -

I thank you all for the valuable  input. It cleared some of my doubts but
also created more.

I am not clear with zones, zone groups and assigning HVAC's to zone groups.
If I have 70 apartments, each apartments is one zone, i group all these
apartments into one zone group and assign the PTAC unit I have created.

Does assigning the PTAC to the zone group mean that each zone within the
zone group is assigned to one PTAC unit?

Screen 13 and 14 in DD wizard seem to be conflicting. I entered all the data
on screen 13 for the whole building.

But after I group my zones on screen 14 the activity area allocation uses
the percentages on screen 13 for each zone group.

I am attaching screen shots of screen 13 and 14.

Please advise on the above questions.

Thanks for all the advise.

Pranita.

On Tue, Dec 7, 2010 at 5:22 PM, Nick Caton <ncaton at smithboucher.com> wrote:

>  Pranita et al,
>
>
>
> In this situation, you must either (A) define separate zones to define the
> multiple systems as they exist, or (B) stick to your guns (assumption of
> thermal equivalency), and further “lump together” the individual PTAC’s as
> large, “combined-equivalent” systems.
>
>
>
> The first option would allow you to more easily specify the systems as they
> exist – individually and independent in operation of each other, will be
> more accurate if indeed the units have differing loads on an hourly basis,
> as John is cautioning, and will render any concerns of whether the
> assumption that the individual zones are thermally equal moot.
>
>
>
If I have 70 apartments do I have to create 70 PTAC(Could I use Zone groups
here).
Does the zone groups option assign each zone within the group one system
each (of the system which is assigned to the zone group)



>  If you are concerned that the “multiple systems in one zone” is critical
> for accuracy, you can always define the adjoining internal partitions as air
> walls to thermally connect the adjacent spaces (indirectly the corresponding
> zonal PTAC systems will work together to handle the combined spaces’
> loads).  This seems to match the real-world  behavior you’re seeking to
> model.
>

How could I assign mutliple systems to one zone?

>
>
> The second option will actually be harder for you (the modeler) in the long
> run, as you must average-together /sum the units’ parameters to come up with
> an equivalent collective system – efficiency/capacity/scheduling/etc… if the
> validity of the “thermally equivalent” assumption is questionable, so is the
> decision to have their systems to act as one – it’s your call.
>
>
>
> Combining zones for thermal equivalency is a great technique when it saves
> you work and time, but the approach sometimes can result in more work than
> would otherwise be required in the long run.  If/when actual system zoning
> is readily available at the wizard development stage of my models, I
> personally tend to use that information when defining zones, unless I’m
> certain the flexibility/accuracy benefits offered by a more zonally-accurate
> model will be unnecessary.
>
>
>
> ~Nick
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> Smith & Boucher Engineers
>
> 25501 west valley parkway
>
> olathe ks 66061
>
> direct 913 344.0036
>
> fax 913 345.0617
>
> www.smithboucher.com* *
>
>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *John Aulbach
> *Sent:* Tuesday, December 07, 2010 3:27 PM
> *To:* pranita kothuru; equest-users
> *Subject:* Re: [Equest-users] Systems /Zoning question.
>
>
>
> Pranita:
>
>
>
> Careful about "all units have the same thermodynamic conditions". End rooms
> have two exposures where those in the facing directions have one.
>
>
>
>
>
> John R. Aulbach, PE, CEM
>
> Senior Energy Engineer
>  ------------------------------
>
> *Partner** **Energy***
>
> 1990 E. Grand Avenue, El Segundo, CA 90245
> W: 888-826-1216, X254| D: 310-765-7295 | F: 310-817-2745
>
> www.ptrenergy.com | jaulbach at ptrenergy.com <%7C%20jaulbach at ptrenergy.com>
>
>
>
>
>
>
>  ------------------------------
>
> *From:* pranita kothuru <pranita.kothuru at gmail.com>
> *To:* equest-users <equest-users at lists.onebuilding.org>
> *Sent:* Tue, December 7, 2010 12:41:53 PM
> *Subject:* [Equest-users] Systems /Zoning question.
>
> Hello All -
>
>
>
> I am modeling a multifamily 4 floors buildings in eQuest. I created
> seperate zones for corridors and living spaces. My living spaces have PTAC
> units and corridors have seperated HVAC system.
>
>
>
> In DD wizard screen 1 what do I have to choose for 'System Per area'.
>
>
>
> All the living spaces were  zoned as one big zone (considering that all
> units have same thermodynamic conditions).
>
>
>
> If I choose system per zone, this can be wrong because I have more than one
> PTAC units in that given zone(as several apats were clubbed to be in one
> zone).
>
>
>
> Please advice.
>
>
>
>
>
> --
>
> *- Pranita *
>
>
>
>
>



-- 

*- Pranita *
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