Re: [EnergyPlus_Support] Heating/Cooling Load

["Michael J. Witte" <mjwitte@xxxxxxxx>]

Two examples of comparing EnergyPlus heating load with UAdeltaT have 
been uploaded into the Examples folder in the files area of the 
EnergyPlus_Support group at yahoogroups.com  These examples show what 
values from the EnergyPlus output are required to compute UAdeltaT.  
One if for a concrete slab, the other is for a simple R-layer (the 
same one that Celmens used)  Perhaps this will help clear things up.

Mike



On 30 Oct 2002, at 17:00, Clemens Felsmann wrote:

> Derek,
> 
> I think this is not a problem of  the so-called "equivalent" deltaT.
> When I simulate a design day with constant ambient conditions, no sun,
> no gains no HVAC-system just a building than I can expect a constant
> cooling/heating load, can't I ? This load also should  meet the
> UAdeltaT.
> 
> Clemens
> 
> --
> 
> Dr.-Ing. Clemens Felsmann
> Institut für Thermodynamik und TGA der TU Dresden
> Tel.: 0351/463 3 5177
> Fax: 0351/463 3 7888
> mail: felsmann@xxxxxxxxxxxxxxxxx
> ----- Original Message -----
> From: "Derek McGarry" <derekm@xxxxxxxxxxxxxxxxxx>
> To: <felsmann@xxxxxxxxxxxxxxxxx>
> Sent: Wednesday, October 30, 2002 3:09 PM
> Subject: RE: [EnergyPlus_Support] Heating/Cooling Load
> 
> 
> > Clemens,
> >
> > I do not recall the previous questions and answers, so I hope I am
> > not repeating anyone.  Some possible reasons for discrepancy:
> >
> > For heat transmission through the walls and roof, are you using
> > actual deltaT or "equivalent" deltaT?  The equivalent deltaT
> > accounts for solar exposure, thermal mass, daily temperature range,
> > solar absorptance of the exterior, and probably some other factors
> > as well.  These values can be
> much
> > higher than actual deltaT.
> >
> > For heat transmission through the windows, are you accounting for
> > solar loads on top of conductance in your manual calculations. 
> > These loads can also be much higher than simple UAdeltaT
> > calculations.
> >
> > I apologize if this is redundant information.
> > Regards,
> > Derek
> >
> >
> > -----Original Message-----
> > From: Clemens Felsmann [mailto:felsmann@xxxxxxxxxxxxxxxxx]
> > Sent: Wednesday, October 30, 2002 7:09 AM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > Subject: [EnergyPlus_Support] Heating/Cooling Load
> >
> >
> > Dear Group members,
> >
> > the zone heating/cooling load calculation for both steady state
> > conditions at design days as well as transient conditions during a
> > run period results in values that are 30...400 times higher than a
> > UAdeltaT calculation. The previous questions/answers didn't really
> > help.
> >
> > Attached there is the *.idf file.
> >
> > Thank you for answer/comment.
> >
> > Clemens
> >
> > --
> >
> > Dr.-Ing. Clemens Felsmann
> > Institut für Thermodynamik und TGA der TU Dresden
> > Tel.: 0351/463 3 5177
> > Fax: 0351/463 3 7888
> > mail: felsmann@xxxxxxxxxxxxxxxxx <mailto:felsmann@xxxxxxxxxxxxxxxxx>
> >
> 
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