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

RE: [EnergyPlus_Support] diffuse solar



Hi, HuJia  
 
I noticed that you are very interested in finding the various fields in the weather file.
 
My former student  Mr. Ooi KB, in a PhD program now, is very interested in findint out how to use:
 
Global horizontal, HIR, Cloud cover, ODT and RH, to get the Direct Normal and Diffused Horizontal fields in the EPW.
 
He can get those five sets of data from the Kuching Met. Station for his work in East Malaysia.  However, he does not know how to divide the Global into the Direct Normal and Diffused horizontal, which the EPlus use for simulation..

 Dr. Li  

P.S. for Linda.  Do you have any sub-routine in Fortran or any programming language,  to generate these two missing fields in EPW. (Direct normal and  Diffused Horizontal from Global horizontal, HIR, Cloud cover, ODT and RH) 
 
He passed on the sub-routine from ticket #2013 for me to solve his ground surface temperature calculation. [EnergyPlus #2013]: Basement outside surface temperatures.  I am studying it and see whether all the data are available, to run it as a C++ program. 
 
What he really nead is the correct solar radiation level through the windows, so that the simulated and the measured room temperature can match. 
 
He tried measring the DIrect Normal using a Pyranometer.  Because the spectrum of this device is wider, the measured value was about 30% higher. 

 Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: hujia06@xxxxxxxxx
Date: Mon, 1 Feb 2010 10:53:00 -0500
Subject: Re: [EnergyPlus_Support] diffuse solar

 
Thank you, Dr. Li
 
Yes, it follows time shift using formula (PDF 1994) for temperature varibales. But I also find some variables like Diffuse Solar does not follow the rule: hourly point values reported are not the same as the hourly value in weather file in timestep interval .report.
 
 
yes, I try to set up TimeStep = 4, in an hourly interval report, the value is the average. In a time step report, the output is unchang
On Mon, Feb 1, 2010 at 7:53 AM, YuanLu Li <yli006@hotmail.com> wrote:
 

I think, these minor time shift and averaging appears with other variables as well.
 
For example, the outside dry bulb temperature listing at the output is unchanged at the hourly points when using timestep as listing interval (same as the EPW hourly value).  When listed as in a  hourly interval report, the value is the average of the preceding hour, which is slightly different from the original list value in the EPW.and is the same as the half hour points of the time step listing.
 
I have a feeling that this is done by the post processor using the ESO in time steps, and not at the simulation time.


 Dr. Li   
 

To: EnergyPlus_Support@yahoogroups.com
From: hujia06@gmail.com
Date: Sun, 31 Jan 2010 20:06:15 -0500
Subject: [EnergyPlus_Support] diffuse solar

 
Hi, all
 
In EnergyPlus, when timestep = 4, the diffuse solar in weather file is different from the output at the same hour. For example, in weather file, at 9:00, the diffuse solar is 58, while in the output, 58 appears at 8:30. This rule seems different from interpolation mentioned in help ref.
 
In calculating Daylight Factor, EP ref. mentions it uses hourly DF and then  interpolate the two hour DF to calculate the DF at time step in  one hour. So when calculating Daylight Factor, the Energyplus adopts which hour values of Diffuse and direct Radiation in the Outputfile?  Does EP use 58 (at 8:30 in the output), or use value at 8:00 in output (average values at 7:30 and 8:30, which are corresponding to 8: 00 and 9:00 in the weather file respectively) ? .
 
Thanks in advance,
 
jia




All your Hotmail contacts on your phone. Try it now.






Not using Hotmail on your phone? Why not? Get it now.

__._,_.___


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 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.



Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe

__,_._,___