[Radiance-general] Help - Radiance / LEED

Thu Apr 21 14:37:48 PDT 2011

Hi Ignacio,

What website did you visit? Because I can point you to a bunch of other websites with far nicer Radiance renderings than mine!  =)  I agree though, Radiance is nice because it gives you useful data, not just "pretty pictures".

OK, your second paragraph below is quite the unit salad. Let's sort this out as best I can, not having Ecotect to look at. You say "Ecotect give the options to calculate Radiance (luminace) cd/m2 or Irradiance (illuminance) lx/m2".  You're mixing and matching quantities here. For LEED daylighting calcs, you ultimately need illuminance. This is lumens/m^2, NOT lux/m^2.  1 Lux = 1lm/m^2. So, just make sure you are asking for illuminance.  Not irradiance, not luminance, but illuminance -- which should be in lux, or lumens/m^2. Next, you mention this node value conversion. I assume a node value is a calculation grid point. Your conversion value is correct to convert from metric units to imperial units. So, assuming you are indeed calculating illuminance, in lux (lumens/m^2), then multiplying those values by 0.0929030436 will convert the values to footcandles (lumens/m^2).

Hope this helps, I'm not really sure about any of the GUI specific questions you have because I don't use or have Ecotect.

Rob Guglielmetti  IESNA, LEED AP
Commercial Buildings Research Group
National Renewable Energy Laboratory
1617 Cole Blvd MS:RSF202
Golden, CO 80401
T. 303.275.4319
F. 303.630.2055
E. robert.guglielmetti at nrel.gov<mailto:robert.guglielmetti at nrel.gov>

From: Ignacio Fajardo <primiark at gmail.com<mailto:primiark at gmail.com>>
Reply-To: Radiance general discussion <radiance-general at radiance-online.org<mailto:radiance-general at radiance-online.org>>
Date: Thu, 21 Apr 2011 12:51:19 -0600
To: Radiance general discussion <radiance-general at radiance-online.org<mailto:radiance-general at radiance-online.org>>
Subject: Re: [Radiance-general] Help - Radiance / LEED

Hi!

Rob I visit your website and I like a lot your radiance renders!! just perfect, I render with other programs and maxell is closer to radiance, but radiance gives you data... more usefull.

About my LEED doubts I answer myself, because Ecotect give the options to calculate Radiance (luminace) cd/m2 or Irradiance (illuminance) lx/m2, so, I´m sure that we are ok with that because you choose cd/m2 option.
Now, to convert cd/m2 to cd/ft2 for LEED  I need to convert each node values - V*0.092903 (V is the node value, and 0.09... is the value to transform 1cd/m2 to cd/ft) in Ecotect you can do that in grid management.
I hope this informations can be usefull ... anyway, comments  are welcome to be sure what I´m doing.

Cheers

2011/4/20 Guglielmetti, Robert <Robert.Guglielmetti at nrel.gov<mailto:Robert.Guglielmetti at nrel.gov>>
Hi Ignacio,

As Lars pointed out, your questions at this point are more about how to get Ecotect to tell Radiance what you want to do. Hopefully some Ecotect users on the list can chime in about this…

Rob

From: Ignacio Fajardo <primiark at gmail.com<mailto:primiark at gmail.com><mailto:primiark at gmail.com<mailto:primiark at gmail.com>>>
Reply-To: Radiance general discussion <radiance-general at radiance-online.org<mailto:radiance-general at radiance-online.org><mailto:radiance-general at radiance-online.org<mailto:radiance-general at radiance-online.org>>>
Date: Wed, 20 Apr 2011 06:53:52 -0600
To: Radiance general discussion <radiance-general at radiance-online.org<mailto:radiance-general at radiance-online.org><mailto:radiance-general at radiance-online.org<mailto:radiance-general at radiance-online.org>>>
Cc: John Mardaljevic <jm at dmu.ac.uk<mailto:jm at dmu.ac.uk><mailto:jm at dmu.ac.uk<mailto:jm at dmu.ac.uk>>>
Subject: Re: [Radiance-general] Help - Radiance / LEED

Hi Rob
I feel a litle lost here .... have two doubt :
- The first is how to specify Radiance calculate irradiance
I was searching  where to specify -I (the capitol i) to rtrace in Radiance to calculate irradiance instead radiance and I found in Autodesk Ecotect Calculation wizard - Radiance Analysis (step 10-11) the -I blank, but i dont know what to do because is already wrote and have a blank beside. Others command have diferents values. I´m in the right place to specify?

- My second doubt is in what place i need to  "mutiply the rgb irrandiance values by V lambda"  I need to be in Analysis Grid Management - Edit Grid Data in Ecotect ?
Rob I´m  really  thankful for your help.
Best regards
2011/4/15 Ignacio Fajardo <primiark at gmail.com<mailto:primiark at gmail.com><mailto:primiark at gmail.com<mailto:primiark at gmail.com>>>
Thanks for your help! I´m gonna be honest, I need to study your answers.
Once I get there, I will certainly write you again!

Best Regards

2011/4/15 John Mardaljevic <jm at dmu.ac.uk<mailto:jm at dmu.ac.uk><mailto:jm at dmu.ac.uk<mailto:jm at dmu.ac.uk>>>
Hi Zack,

Indeed, the CIE skies can be defined by diffuse horizontal illuminance or zenith luminance. Both options of course available in gensky.  I'm not too familiar with the procedures used to estimate sky type and magnitude since I invariably use climate data as the basis for defining skies.  For what it's worth, I've long believed that there was a 'disconnect' between what the sky model researchers were doing and what end-users might actually want, i.e. a means of selecting sky type from basic quantities in the standardised climate files.

Even if one could claim that a particular clear sky output was plausible, it still seems wacky to predict for a clear sky without sun. I've updated my commentary on this with a graphic to show just how much might be missing if you don't include the sun:

http://www.iesd.dmu.ac.uk/~jm/doku.php?id=academic:daylight-compliance#daylight_leed

BTW - the latest public review draft of LEED 2012 goes away from this standard clear sky and requires the user to find the average hourly values between the clearest and cloudiest days within 15days of Sept 21 and Mar 21st. Someone must have been listening to your concerns!

Perhaps, half-listening.  Averages for daylighting quantities can be a confounding notion, and often lead to contortions best left to people who enjoy doing this:

http://en.wikipedia.org/wiki/Twister_(game)

Do you have actual wording from the LEED draft?

Best

John

-----------------------------------------------
Dr. John Mardaljevic
Reader in Daylight Modelling
Institute of Energy and Sustainable Development
De Montfort University
The Gateway
Leicester
LE1 9BH, UK
+44 (0) 116 257 7972
+44 (0) 116 257 7981 (fax)

jm at dmu.ac.uk<mailto:jm at dmu.ac.uk><mailto:jm at dmu.ac.uk<mailto:jm at dmu.ac.uk>>
http://www.iesd.dmu.ac.uk/~jm

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       Jorge Ignacio Fajardo F-A
                  Arquitecto MDCS

iBSA - Ingeniería Blanda S.A
USGBC Member
Jean Mermoz 12, of. D
Of.: (562) 934.7083
Cel. (567) 8782497

Las Condes, Santiago. Chile

--
       Jorge Ignacio Fajardo F-A
                  Arquitecto MDCS

iBSA - Ingeniería Blanda S.A
USGBC Member
Jean Mermoz 12, of. D
Of.: (562) 934.7083
Cel. (567) 8782497

Las Condes, Santiago. Chile

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Radiance-general mailing list
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--
        Jorge Ignacio Fajardo F-A
                   Arquitecto MDCS

iBSA - Ingeniería Blanda S.A
USGBC Member
Jean Mermoz 12, of. D
Of.: (562) 934.7083
Cel. (567) 8782497

Las Condes, Santiago. Chile