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Re: [EnergyPlus_Support] Multiple sys/common return, deep daylighting ?s
As Fred stated, you cannot connect the same plenum zone to more than one air
handler. One option to consider would be to divide the plenum zone into
multiple zones, one for each air handler. Then use MIXING or CROSS MIXING to
blend the air across the plenums. There may be some time lag to this due to
the way plenum zones are modeled, but it might be close enough for your
purposes.
Mike
On 14 Dec 2007 at 10:44, Fred Buhl wrote:
> Kristin,
>
> EnergyPlus does its air mass balance in each air system. It is not able to
> do a mass balance across multiple air systems. The situation you describe
> would have to be simulated as one system with one return air path or
> multiple
> systems with multiple return air paths that do not interact. As I
> understand it
> the designer is trying to get heat from the interior zone transferred to
> the
> perimeter zone. Using one common return plenum / return air path would
> capture
> some of this effect. In fact, unless the interior return air is ducted
> over to the
> perimeter zone somehow I don't see why this wouldn't be adequate.
>
> Fred Buhl
>
> Kristin Field wrote:
> > Hello, EP folks. Two questions for you:
> >
> > (1) A proposed underfloor & displacement air system will utilize
> > multiple VVT systems, which share a common return plenum and shaft.
> > Can this be modeled explicitly in E+ using air nodes (roomair or
> > other)? The designer claims that during heating the return
> > temperatures in the core will be higher than on the perimeter. As the
> > perimeter VVT systems provide warm air directly they can utilize all
> > warmth in the RA to reduce the heat added to the SA, so it is
> > important to have a valid determination of this mixed RA temperature,
> > and to have distinct systems with separate SA temperature control on
> > each perimeter. Any advice on whether and/or how this could be
> > implemented in EP?
> >
> > (2) One situation we struggle with regularly is the daylighting
> > calculation where the daylit zone is deeper than the thermal zone.
> > This is typical in large open office configurations, with very tall
> > daylight glass (or light-redirecting devices) and dimming ballasts
> > installed to the interior. The daylight zone may be 30' deep, but the
> > thermal zone is typically only 15' deep. The zones are separated in
> > the model by an air wall. Is there a way to explicitly model daylight
> > which passes into this interior zone, without declaring "virtual"
> > exterior walls & windows, etc., at that 15' boundary? I remember that
> > daylight doesn't pass through interior windows, but I'm wondering if
> > there's another way to get it to cross through zones.
> >
> > Thanks for your help!
> >
> > Kristin Field
> >
> >
> >
> > The primary EnergyPlus web site is found at:
> > http://www.energyplus.gov
> >
> > The group web site is:
> > http://groups.yahoo.com/group/EnergyPlus_Support/
> >
> > Attachments are not allowed -- please post any files to the appropriate folder
> > in the Files area of the Support Web Site.
> >
> > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > Documentation link and press the "search" button.
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>
>
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
>
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
>
> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> Documentation link and press the "search" button.
>
> Yahoo! Groups Links
>
>
>
>
>
========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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