# Size of ground the plane

Hi all, I am assessning DF levels in a 4th floor of a building in an unobstructed area, so I am not considering any surrounding building just a ground plane that I modeled as a circle.Almost by chance I discovered increasing the size of my ground plane has a significant effect on my DF. Using a ground plane of 500m radius I had an average of 3.34%, if I increase it to 1000meters I get over 12%. As long as I understand, this should not have such a big effect, should it? Could I be doing something wrong? Can I do something to make sure I get reasonable values?I am running the simulation though DIVA for Rhino in Grasshopper. My radiance parameters are: -ab 7 -ad 2048 -as 1024 -ar 256 -aa 0.1. My ground plane reflectance is 0.25. Thanks in advance, Alejandro

Hi

Are you sure you have also modelled the "infinite" ground plane as a glowing source ? This has to be modelled even if you also put a large disk for the ground plane.

Raphaël

···

________________________________
De : Alejandro Pacheco Diéguez [[email protected]]
Envoyé : jeudi 16 octobre 2014 10:36
À : [email protected]
Objet : [Radiance-general] Size of ground the plane

Hi all,
I am assessning DF levels in a 4th floor of a building in an unobstructed area, so I am not considering any surrounding building just a ground plane that I modeled as a circle.
Almost by chance I discovered increasing the size of my ground plane has a significant effect on my DF. Using a ground plane of 500m radius I had an average of 3.34%, if I increase it to 1000meters I get over 12%. As long as I understand, this should not have such a big effect, should it? Could I be doing something wrong? Can I do something to make sure I get reasonable values?
I am running the simulation though DIVA for Rhino in Grasshopper. My radiance parameters are: -ab 7 -ad 2048 -as 1024 -ar 256 -aa 0.1. My ground plane reflectance is 0.25.
Alejandro

Hello
Raphaël,
by means of glowing source, I assume the reflectance is less than the normal floorForLighting Material. Should 20% as a setting for the ínfinite ground plane be fit?

Niya

-------- Оригинално писмо --------

От: Compagnon Raphaël [email protected]

Относно: Re: [Radiance-general] Size of ground the plane

Изпратено на: Четвъртък, 2014, Октомври 16 12:23:07 EEST

Hi

Are you sure you have also modelled the "infinite" ground plane as a glowing source ? This has to be modelled even if you also put a large disk for the ground plane.

Raphaël

···

________________________________

De : Alejandro Pacheco Diéguez [[email protected]]

Envoyé : jeudi 16 octobre 2014 10:36

Objet : [Radiance-general] Size of ground the plane

Hi all,

I am assessning DF levels in a 4th floor of a building in an unobstructed area, so I am not considering any surrounding building just a ground plane that I modeled as a circle.

Almost by chance I discovered increasing the size of my ground plane has a significant effect on my DF. Using a ground plane of 500m radius I had an average of 3.34%, if I increase it to 1000meters I get over 12%. As long as I understand, this should not have such a big effect, should it? Could I be doing something wrong? Can I do something to make sure I get reasonable values?

I am running the simulation though DIVA for Rhino in Grasshopper. My radiance parameters are: -ab 7 -ad 2048 -as 1024 -ar 256 -aa 0.1. My ground plane reflectance is 0.25.

Alejandro

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Hi,
Another possibility is that the larger ground plane is increasing the interpolation distance and you are getting more values from outside spilled in the calculation. You could try increasing ar or reducing aa to see if it converges. (provided that you have the infinite source, as Raphael says)
Santiago

···

-----Original Message-----
From: Compagnon Raphaël [mailto:[email protected]]
Sent: 16 October 2014 10:23
Subject: Re: [Radiance-general] Size of ground the plane

Hi

Are you sure you have also modelled the "infinite" ground plane as a glowing source ? This has to be modelled even if you also put a large disk for the ground plane.

Raphaël
________________________________
De : Alejandro Pacheco Diéguez [[email protected]] Envoyé : jeudi 16 octobre 2014 10:36 À : [email protected]
Objet : [Radiance-general] Size of ground the plane

Hi all,
I am assessning DF levels in a 4th floor of a building in an unobstructed area, so I am not considering any surrounding building just a ground plane that I modeled as a circle.
Almost by chance I discovered increasing the size of my ground plane has a significant effect on my DF. Using a ground plane of 500m radius I had an average of 3.34%, if I increase it to 1000meters I get over 12%. As long as I understand, this should not have such a big effect, should it? Could I be doing something wrong? Can I do something to make sure I get reasonable values?
I am running the simulation though DIVA for Rhino in Grasshopper. My radiance parameters are: -ab 7 -ad 2048 -as 1024 -ar 256 -aa 0.1. My ground plane reflectance is 0.25.
Alejandro

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Greetings,

DIVA automatically includes the 'infinite ground' source in its calculations. I also suspect that increasing your ar setting will help stabilize your results.

Best,
Alstan

···

On Thu, 16 Oct 2014 19:01:32 +0800, Santiago Torres <[email protected]> wrote:

Hi,
Another possibility is that the larger ground plane is increasing the interpolation distance and you are getting more values from outside spilled in the calculation. You could try increasing ar or reducing aa to see if it converges. (provided that you have the infinite source, as Raphael says)
Santiago

-----Original Message-----
From: Compagnon Raphaël [mailto:[email protected]]
Sent: 16 October 2014 10:23
Subject: Re: [Radiance-general] Size of ground the plane

Hi

Are you sure you have also modelled the "infinite" ground plane as a glowing source ? This has to be modelled even if you also put a large disk for the ground plane.

Raphaël
________________________________
De : Alejandro Pacheco Diéguez [[email protected]] Envoyé : jeudi 16 octobre 2014 10:36 À : [email protected]
Objet : [Radiance-general] Size of ground the plane

Hi all,
I am assessning DF levels in a 4th floor of a building in an unobstructed area, so I am not considering any surrounding building just a ground plane that I modeled as a circle.
Almost by chance I discovered increasing the size of my ground plane has a significant effect on my DF. Using a ground plane of 500m radius I had an average of 3.34%, if I increase it to 1000meters I get over 12%. As long as I understand, this should not have such a big effect, should it? Could I be doing something wrong? Can I do something to make sure I get reasonable values?
I am running the simulation though DIVA for Rhino in Grasshopper. My radiance parameters are: -ab 7 -ad 2048 -as 1024 -ar 256 -aa 0.1. My ground plane reflectance is 0.25.
Alejandro

_______________________________________________
[email protected]
____________________________________________________________
Electronic mail messages entering and leaving Arup business
systems are scanned for acceptability of content and viruses

_______________________________________________
[email protected]

All the tools I'm aware of include this distant ground source automatically. Santiago is right, the issue here is your huge local ground plane and consequently relatively low -ar value. For a single story building, the rule of thumb is your ground plane plan projection should be about 5x the window head height. With that, even your current -ar of 256 should be adequate to avoid these interpolation errors.

-rob

···

On Oct 16, 2014, at 5:32 AM, J. Alstan Jakubiec <[email protected]> wrote:

Greetings,

DIVA automatically includes the 'infinite ground' source in its calculations. I also suspect that increasing your ar setting will help stabilize your results.

Best,
Alstan

On Thu, 16 Oct 2014 19:01:32 +0800, Santiago Torres <[email protected]> wrote:

Hi,
Another possibility is that the larger ground plane is increasing the interpolation distance and you are getting more values from outside spilled in the calculation. You could try increasing ar or reducing aa to see if it converges. (provided that you have the infinite source, as Raphael says)
Santiago

-----Original Message-----
From: Compagnon Raphaël [mailto:[email protected]]
Sent: 16 October 2014 10:23
Subject: Re: [Radiance-general] Size of ground the plane

Hi

Are you sure you have also modelled the "infinite" ground plane as a glowing source ? This has to be modelled even if you also put a large disk for the ground plane.

Raphaël
________________________________
De : Alejandro Pacheco Diéguez [[email protected]] Envoyé : jeudi 16 octobre 2014 10:36 À : [email protected]
Objet : [Radiance-general] Size of ground the plane

Hi all,
I am assessning DF levels in a 4th floor of a building in an unobstructed area, so I am not considering any surrounding building just a ground plane that I modeled as a circle.
Almost by chance I discovered increasing the size of my ground plane has a significant effect on my DF. Using a ground plane of 500m radius I had an average of 3.34%, if I increase it to 1000meters I get over 12%. As long as I understand, this should not have such a big effect, should it? Could I be doing something wrong? Can I do something to make sure I get reasonable values?
I am running the simulation though DIVA for Rhino in Grasshopper. My radiance parameters are: -ab 7 -ad 2048 -as 1024 -ar 256 -aa 0.1. My ground plane reflectance is 0.25.
Alejandro

_______________________________________________
[email protected]