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Re: [EnergyPlus_Support] Re: How to change the solar radiation calculation model in Energyplus





Hi, Jeremiah

      Thanks for your suggestion and answers. I will try to do it. Thanks.


Regards

Jallen


2013/11/5 Jeremiah Crossett <jcrossett@xxxxxxxxxxxxxxx>
 

The .EPW file can be edited by opening it with the weather converter utility and convert to CSV, then can be edited in excel and changed back to .EPW with the weather converter. 

I think that your pyranometer readings should be close to the value found for GHI at that hour. The hourly data is from various years over the averaging period so it may not be the same.  

There are two approaches you could take. 

  1. Use actual meteorological year data for the year of measure, or the closest year available. 
  2. Use your actual solar measurement data to replace the hourly averages for those hours. (I think that if you only enter GNI that the weather converter will calculate direct and diffuse for you- but you should check the documentation to be sure.)



Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
  





On Tue, Nov 5, 2013 at 10:30 AM, Jinqing Peng <jallenpeng@xxxxxxxxx> wrote:
 

Dear Jeremiah,

         What does you mean to change the weather data?

Regards

Jallen


2013/11/5 Jeremiah Crossett <jcrossett@xxxxxxxxxxxxxxx>
 

Correct. However you could change your weather data. 



Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
  





On Tue, Nov 5, 2013 at 9:57 AM, Jinqing Peng <jallenpeng@xxxxxxxxx> wrote:
 

Dear Jeremiah,

        You mean I can't change the solar radiation calculation model for a long period simulation, such as one month, is that right?

Regards

Jallen


2013/11/5 Jeremiah Crossett <jcrossett@xxxxxxxxxxxxxxx>
 



 I think that the solar model is a function of the weather file, from memory solar is measured in global horizontal witch is split into direct and diffuse using a modified version of the perez model. 

The design day info has model options that are not weather file based.  One of witch was developed by ZhangHuang. Huang has done a lot of work on weather data and some initial E+ conversion from doe2.1e. 


The solar calculations in Energy Plus solar distribution FullInteriorAndExteriorWithReflections is more useful for calculations of solar heat gain for specific interior surfaces, however it requires convex zones and does not work well with window multipliers. 

Solar can be effected by ground and snow reflectivity, as well as transmittance schedules of shading surfaces. 

The material properties setting for solar absorbency (inverse of reflectivity) also have effects.

Yes it would be interisting to have solar modeling options, but I m not sure what would be useful in addition to what is currently available. 







Jeremiah D. Crossett  | Senior Analyst  |  Phase Change Energy Solutions
120 E. Pritchard St.  | Asheboro, NC 27203  | Mobile 503-688-8951
  





On Tue, Nov 5, 2013 at 8:00 AM, Jill Dalglish <jill.dalglish@xxxxxxxxxxxxxxxxxxxxx> wrote:
 

I am interested in this question.  How are you measuring the solar radiation?









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