[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [EnergyPlus_Support] Example files 5ZoneNightVent2 & 5ZoneNightVent3

Eric,

5ZoneNightVent2 & 5ZoneNightVent3 show 2 different ways of simulating
the same thing: precooling by night ventilation. 5ZoneNightVent2 uses
Ventilation objects, which operate at the zone level. In this case they
can be pictured as little intake fans on each zone. The Ventilation object
also allows one to do a crude form of natural ventilation, using other 
inputs.
But in this case it is used for mechanical ventilation.

5ZoneNightVent3 illustrates night ventilation using the System Availability
Manager:Night Ventilation object along with Fan:Night Vent Performance. This
scenario can be visualized as night ventilation using the central air 
system fan
with the zone terminal unit dampers wide open & the fan running at 1/3 
of max speed.

The 2 cases are slightly different. For one thing, the inputs are 
different: 18C min temperature versus 15.
5ZoneNightVent3 has a "VentTempSched:" whereas 5ZoneNightVent2 has 
nothing similar. Most inportant
5ZoneNIghtVent2 makes all its on/off decisions at the individual zone 
level whereas 5ZoneNightVent3 makes
a decision at the system level - all zones are ventilated or none. Also 
in 5ZoneNightVent3 return air goes
through the plenum before it is exhausted, while in 5ZoneNightVent2 the 
plenum is inactive at night. So there are
plenty of differences that can lead to different results even though the 
fan power and heat are treated the same.

My feeling is that 5ZoneNightVent3  is more realistic - it is closer to 
what would be done in the real world.
5ZoneNightVent2 might do better at showing the night venting potential..

eric_zhou1223 wrote:

>Hi all£¬
>
>I am studying the example files 5ZoneNightVent2 & 5ZoneNightVent3. 
>They look like almost same except the definition way of night vent.
>Are they only different simulation methods of night vent?
> Users may attain their goals using any of these two opptions?  
>Though paramters of two files are same, it reads "In this case, we 
>see no benefit with night ventilation compared to the base case 
>(5ZoneNightVent1.idf)" in the Basic file description of  
>5ZoneNightVent3, while in 5ZoneNightVent2 it reads it can save a 
>modest benefit with night ventilation. Is it right or am I missing 
>something?
>
>In another word, What is essentially the difference between 
>5ZoneNightVent2 & 5ZoneNightVent3? 
>
>By the way, which fan will be used to excute the night purge in 
>5ZoneNightVent2, still the central supply fan? How can the "intake 
>air" leak off at last from the spaces after it finish precooling the 
>rooms? I think there should be a return-air orgniaztion but in fact 
>I don't find it out. Or it leaks out from the plenum /cracks?
>  
>
The fan(s) would be zone intake fans, not the central system fan, which 
is off in this case. There
is no return or central exhaust. The air magically vanishes, presumable 
by exfiltration.

>Sorry for the long might-be unclear quesitons but I am realy looking 
>forward to hear your explanation soon. THank you.
>
>Eric 
>
>
>
>
>
>
>
>
>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.idf and press the "search" button.
> 
>Yahoo! Groups Links
>
>
>
> 
>
>
>  
>


------------------------ Yahoo! Groups Sponsor --------------------~--> 
Home is just a click away.  Make Yahoo! your home page now.
http://us.click.yahoo.com/DHchtC/3FxNAA/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.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf and press the "search" button.
 
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/