Re: [EnergyPlus_Support] Re: relative/worldcoordinatesystem

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

Li:  Since you are going from 1.0.1 to 1.0.3, it would be cleaner to 
uninstall the old one first.  Or you can keep both on your system at 
the same time if you install the new one into a different directory 
name.

Mike


On 4 Mar 2003, at 19:25, zl21e zl21e@xxxxxxxxx wrote:

> Mike,
> Thank you for your explanation.  BTW, if I download the new version of
> e+, do I need to delete the old one first?
> 
> Thanks again!
> 
> Li
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte" 
> <mjwitte@g...> wrote:
> > Li:  See answers below.  Mike
> > 
> > 
> > On 4 Mar 2003, at 5:24, zl21e zl21e@y... wrote:
> > 
> > > Hello, Everyone,
> > > I have some questions about the relative/worldcoordinatesystem.
> > > 
> > > For relative coordinate system, each zone origin coordinates are
> > > specified relative to the buiding origin (which is 0,0,0).  Every
> > > surface vertice's coordinates in that zone are relative to the 
> zone
> > > origin coordinates.  For world coordinate system, all zone origin
> > > coordinates are (0,0,0). Every vertice's coordinates are absolute
> > > coordinates to (0,0,0). Is that right?
> > 
> > Yes, that is correct.  In addition, with relative coordinates, the
> > building north axis field becomes active.
> > 
> > > 
> > > In the sample file s1r3DD.idf, relative coordinate system is 
> used. 
> > > However, all zone origin coordinates are (0,0,0). Every vertice's
> > > coordinates are absolute coordinates to (0,0,0). Is it the same 
> as
> > > world coordinate system?
> > 
> > It is almost the same.  With relative coordinates, the building 
> north 
> > axis could be applied.  With world coordinates, it cannot.  (By 
> the 
> > way, s1r3DD is quite old, you may need to upgrade versions.)
> > 
> > > 
> > > In the sample file VAVSingleDuctReheat.idf, world coordinate 
> system is
> > > used.  However,  each zone origin coordinates are specified 
> relative
> > > to the buiding origin (which is 0,0,0). Every vertice's 
> coordinates
> > > are still absolute coordinates to (0,0,0). Why does this happen?
> > > 
> > 
> > When daylighting is used, the coordinates for the daylighting 
> > reference points are always relative to the zone origin.  If using
> > world coordinates, the zone origins may be left at (0,0,0) and 
> then 
> > the daylighting reference points would effectively be in world
> > coordinates.  Or, the surfaces could be in world coordinates with 
> non-
> > zero zone origins, as in this example.  In this case, daylighting
> > reference points would be in relative coordinates.  In this
> > particular example, daylighting is not used, so there is no real
> > reason for non-zero zone origins, but it does not affect the 
> results. 
> >  (Not all of our examples represent the best practice.)
> > 
> > 
> > > Thank you!
> > > 
> > > Sincerely,
> > > Li Zhang
> > > Department of Mechanical Engineering
> > > Iowa State University
> > > Ames, IA 50010
> > > 



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