Re: [EnergyPlus_Support] Unable to autosize VAV dx coil

["Edward Lyon" <eglyon@xxxxxxx>]

Regarding the warm-up issues, I think that when you use autosize with
warm-up, you are asking for a size that will meet your warm-up time
schedule (heat this space up in the next time step).  A real system may
have some extra capacity built in for warm-up, but warm-up (or
cool-down) often uses just the max available capacity and does not
include outside ventilation air during the warm-up period.  I would
recommend starting your model without a scheduled warm-up (using the
design day) to initially size your system, and then evaluate the length
of time needed for warm-up by fixing the system max capacity for a
second run.  If you find that the warm-up takes too long, you may want
to increase the system size (usually the code allows 10% or so anyway)
to met warm-up needs.

I'm not sure that E+ implements a dynamic schedule for warm-up.  A real
building management system tries to learn the actual building dynamics
and change the start of warm-up so that the building meets set point by
the time occupancy starts.  Mike can probably answer this question
better, but I don't think any kind of variable warm-up start is
currently available.  If it were, you would probably have to run a year
simulation first so that the control learned the building dynamics given
the weather data and then run a second year to get energy usage.  Your
current option may be to evaluate design day building response to your
warm-up and then try generating a variable schedule or average schedule
for the warm-up period that satisfies the building most of the time but
may not be optimal.

Ned Lyon

Senior Project Manager
Simpson Gumpertz & Heger Inc.

41 Seyon Street
Building #1, Suite 500
Waltham, MA  02453

Phone:  781-907-9000
Fax:  781-907-9009



------------------------ Yahoo! Groups Sponsor --------------------~--> 
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!
http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/dkFolB/TM
--------------------------------------------------------------------~-> 

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.
 
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/