All,

I have a LEED v4 project that will be using Solatubes so I need to use Option 2 to test compliance with the Daylight credit.  

I am not seeing a calculation yet specifically for Option 2 but I noticed some GH definitions for determining the correct sky values.

Has anyone come up with, or is Diva working on, an Option 2 calculation & results display?

(The Option 2 Results button currently in Diva loads in data with a 0-100fc threshold - see attached results image.) 

Thank you in advance!

Sandy

Tags: 2, option

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Hi Sandy,

The GH components have no built-in feature for this, but it's pretty easy to do on your own.  Just set up two illuminance runs on 9/21 (9am, 3pm) with a clear sky, and count the fraction of grid sensors receiving the target lux (107-5382).  More than 75% gives you a point.

Jon

Hi Jon, 

I don't think your clear sky and target range fulfill LEEDv4 Option 2 requirements. 

Cheney  

This is true ... the target range is now 300-3000 lux, and you have to use local weather data (e.g. the PerezFromWeatherFile option).  You can choose any two days within 15 days of 3/21 and 9/21 (respectively) and use the average. Btw Perez skies on clear days tend to be brighter than the CIE clear sky, so this probably makes achieving the credit easier. :)

Hi Jon, 

Thank you for the clarification! Further questions: 

I)

The LEED guide writes:

4) From the TMY, select a day within 15 days of march 21 that has the clearest sky condition at 9am

5) Determine the direct horizontal irradiance (Wh/m2) values at 9am selected in September and at 9am for the day selected in march. Average the two values and use the result in the 9am simulation as the direct horizontal irradiance input. If the file does not explicitly state direct horizontal irradiance, calculate it as follows:

http://diva4rhino.com/forum/topics/leed-v4-credit-7-daylight-option... Mathias made script for calculating average direct horizontal irradiance . However, a resent update  http://diva4rhino.com/forum/topics/automatic-shading-not-working-wi... According to the Option 2 in LEED you should pick one day in spring and one day in autumn (the most favorable) and then average these two values for 9.00 and 15.00, which as I said is not exactly what the definition you used does.

We don't have a confirmed solution for calculating the average values. 

II.  I am quite interested in what you mentioned "PerezFromWeatherFile option". By using this option, are we able to avoid Question I calculations?  To me, if we do that calculation, we have to choose "PerezFromGlobalHorizontalradiance" option, don't we? 

III. Am I right to say, the current DIVA4Rhino interface cannot do LEEDv4 option2 calculation. Although you can run LEED 2009 calculation and view the results in LEEDv4 option2 format, many people (I test it myself as well) report wrong results. 

Looking forward to hearing from you. Many thanks. 

Cheney  

Jon Sargent said:

This is true ... the target range is now 300-3000 lux, and you have to use local weather data (e.g. the PerezFromWeatherFile option).  You can choose any two days within 15 days of 3/21 and 9/21 (respectively) and use the average. Btw Perez skies on clear days tend to be brighter than the CIE clear sky, so this probably makes achieving the credit easier. :)

Ah, I think you read the guide more closely than I did. :)  In that case you should use PerezFromDirectAndDiffuse (you'll want to expose the direct and diffuse inputs from the hidden params on the Sky component).  You can grab the irradiance data from the Archsim Weather component. I suppose this is a bit of a pain, but the beauty of scripting is you only have to do it once. :)

You can of course use the toolbar to run the illuminance calc, but you'd still have to figure the sky inputs yourself.

Thanks again Jon!

When you say "toolbar", I guess it means Dive4Rhino interface? The latest Diva does not offer us the option of customizing "Direct" and "Diffuse" by using "Custom Sky (Perez)". Instead, it only gives you the choice of "Global Horizontal Irradiance".  How do we input Direct and Diffuse individually? Or does it mean we can not run LEEDv4 Option2 calumniators by using toolbar? Only possible in grasshopper environment?  



Jon Sargent said:

Ah, I think you read the guide more closely than I did. :)  In that case you should use PerezFromDirectAndDiffuse (you'll want to expose the direct and diffuse inputs from the hidden params on the Sky component).  You can grab the irradiance data from the Archsim Weather component. I suppose this is a bit of a pain, but the beauty of scripting is you only have to do it once. :)

You can of course use the toolbar to run the illuminance calc, but you'd still have to figure the sky inputs yourself.

image attached for your reference

Cheney said:

Thanks again Jon!

When you say "toolbar", I guess it means Dive4Rhino interface? The latest Diva does not offer us the option of customizing "Direct" and "Diffuse" by using "Custom Sky (Perez)". Instead, it only gives you the choice of "Global Horizontal Irradiance".  How do we input Direct and Diffuse individually? Or does it mean we can not run LEEDv4 Option2 calumniators by using toolbar? Only possible in grasshopper environment?  



Jon Sargent said:

Ah, I think you read the guide more closely than I did. :)  In that case you should use PerezFromDirectAndDiffuse (you'll want to expose the direct and diffuse inputs from the hidden params on the Sky component).  You can grab the irradiance data from the Archsim Weather component. I suppose this is a bit of a pain, but the beauty of scripting is you only have to do it once. :)

You can of course use the toolbar to run the illuminance calc, but you'd still have to figure the sky inputs yourself.

Ah, I think they used to be separate. I shouldn't speak for the LEED reviewers, but I can't think of a good reason to disallow using GHI instead.  The irradiance data in the vast majority of TMY files is modeled, not measured -- and the direct component ends up being a function of GHI and solar zenith angle.  Anyway, I guess use Grasshopper if you want to play it safe.

Hi Jon, 

I strongly agree with you that GHI should be used rather than Direct and Diffused since none of them are measured in TMY. Looks like for now, only grasshopper results would be safe. Do you have any workflow of combining two illuminance calcs and interpret them on one image output? 

Last but not least, the potential bug in DIVA toolbar, I am wondering when it could be fixed:

1. the toolbar allows us to conveniently interpret two illuminance calcs in LEEDv4 option2 format (similar to LEED2009) 

2. However, the range in LEEDv4 option2 has been set as 0-100 fc (which is totally wrong and many users report this issue). I built a simple box model (running two illuminance calcs seperately) and test it as follows: 

3. The same two illuminance calcs and I use LEED2009 way to interpret the results. It seems working seamlessly. 

 

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