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

[EnergyPlus_Support] RE: Shading of many overhangs and calculation time




Hi,



Thanks for your answers. I've been investigating this question a bit further and here are my current conclusions:



  1. My assumption that a Shading:Overhang object only shades the fenestration it's attached to was wrong. E+ will find all the receiving surfaces in the model for a given overhang. A look at the Surface Shadowing Summary report shows that clearly.

  2. However, a detached shading object such as Shading:Building:Detailed will be automatically mirrored by E+. Which means that for overhangs at least, that adds unnecessary shading calculations. This behaviour can be disabled with the following statement: OutputDiagnostics, DoNotMirrorDetachedShading; To be used wisely!



So there is a slight advantage (in terms of calculation time; I'm ignoring other considerations for the sake of this argument) in using Shading:Overhang above Shading:Building:Detailed for modelling a rectangular overhang.



I'm still working on this tower with lots of overhangs. Because each overhang has a lot of shadow receiving surfaces, I'm getting loads of the following warnings (or at least I think that's the reason):



   ** Warning ** Too many figures [>=100000] in a shadow overlap

   **   ~~~   ** Overlapping figure=Mir-SUB SURFACE  28-40-14 OVERHANG, Surface Class=[Shading]

   **   ~~~   **   This error occurred 2 times.

   **   ~~~   ** Figure being Overlapped=SURFACE  16-27-581, Surface Class=[Wall]

   **   ~~~   ** Figure being Overlapped=SURFACE  16-27-17049, Surface Class=[Wall]



Am I just supposed to ignore these in this case, as hinted here:

http://energyplus.helpserve.com/Knowledgebase/Article/View/70/17/too-many-figures-in-a-shadow-overlap



Cheers,

Patrick



---In energyplus_support@xxxxxxxxxxxxxxx, <o.hans@...> wrote:

@Jeremiah



Shading:Overhang is not necessarily symmetrical. The projection from the window corner can be input for each side individually.



> ---In EnergyPlus_Support@xxxxxxxxxxxxxxx, <jeannieboef@...> wrote:
> 
> ------->With shading overhang you have the benefit of a symmetrical model where you could add all your shading in a ratio based method so it would be a global setting- might want to do so on a orientation basis.. Also shading detailed may involve many surfaces, the primary issue with long runtime.  I am not so familar with shading building. Also you might consider use of controlled blinds. 
> 
> 
> Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
<http://www.phasechange.com>www.phasechange.com 
  <http://i.imgur.com/Sldxf.jpg>
> 
> 
> 
> 
>> On Thu, Nov 14, 2013 at 11:02 PM, Patrick Bivona <<mailto:patrick.bivona@...>patrick.bivona@...> wrote:
>>>  
Hello,
>>> I'm working on a high-rise tower block. I'd like to model balcony overhangs that provide shading to the glazing below.
>>> There are 3 objects I can think of using:
1. Shading:Building
2. Shading:Zone:Detailed
3. Shading:Overhang
>>> 
>>> Knowing that I have about 500 balcony overhangs, I'm wondering if there are significant differences in terms of calculation time between these 3 options.
>>> My thinking is that a Shading:Overhang object is only shading the glazing it's attached to. Whereas, for the 2 other options, E+ has to calculate the effect of each shading surface on all the other building surfaces in view.
>>> Does it make that much difference?
>>> Many thanks,
Patrick
>>> 
>>> 
>> 



__._,_.___

Primary EnergyPlus support is found at:
<http://energyplus.helpserve.com>http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

The primary EnergyPlus web site is found at:
<http://www.energyplus.gov>http://www.energyplus.gov

The group web site is:
<http://groups.yahoo.com/group/EnergyPlus_Support/>http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.


<http://geo.yahoo.com/serv?s=97476590/grpId=3387488/grpspId=1705007389/msgId=30773/stime=1385551068>

Your email settings: Individual Email|Traditional
<http://groups.yahoo.com/group/EnergyPlus_Support/join;_ylc=X3oDMTJmanNramlwBF9TAzk3NDc2NTkwBGdycElkAzMzODc0ODgEZ3Jwc3BJZAMxNzA1MDA3Mzg5BHNlYwNmdHIEc2xrA3N0bmdzBHN0aW1lAzEzODU1NTEwNjg->Change settings via the Web (Yahoo! ID required)
Change settings via email: <mailto:EnergyPlus_Support-digest@xxxxxxxxxxxxxxx?subject=Email Delivery: Digest>Switch delivery to Daily Digest | Switch to Fully Featured
<http://groups.yahoo.com/group/EnergyPlus_Support;_ylc=X3oDMTJkMXVuOW82BF9TAzk3NDc2NTkwBGdycElkAzMzODc0ODgEZ3Jwc3BJZAMxNzA1MDA3Mzg5BHNlYwNmdHIEc2xrA2hwZgRzdGltZQMxMzg1NTUxMDY4>Visit Your Group  | <http://info.yahoo.com/legal/us/yahoo/utos/terms/> Yahoo! Groups Terms of Use  | <mailto:EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx?subject=Unsubscribe> Unsubscribe

__,_._,___