LEED modeling

radiance-general
1

Hi All,

Has anyone out there done any daylight modeling for LEED projects? We're considering it, but wondering about how the LEED process affects things. Perhaps the glazing factor option is the way to go, instead of full-on modeling? And what about this sky condition, clear skies at noon on the equinox...including direct sun? Really? Not daylight factors under the CIE 10k? Sure, neither are perfect, but...

Thanks,
Cramer

···

--
*Cramer Silkworth
212 219 2255 | [email protected] <mailto:[email protected]>
Transsolar Inc. | 134 Spring Street Suite 601 | New York, NY 10012

Transsolar Climate Engineering
Technical consulting for energy efficiency and environmental quality in buildings.
New York - Stuttgart - Munich*

2

Hi Cramer,

I've done a fair amount of daylight modeling for LEED
certification/documentation -- more than I'd like to have done, honestly!
At my last job, we would use the glazing factor method if the spaces were
simple enough, and rely on Radiance models for the more complicated
designs. There are spaces that are simply not supported by the glazing
factor method, and then you need to rely on better tools like Radiance or
AGi32 to do the required simulations.

The sky condition is, admittedly, a gross simplification. Better than
daylight factors for predominantly clear climates, though. But you're
right, neither are really adequate for quantifying the daylighting on an
annual basis. Hopefully the emerging tools in Radiance v4.x, and planned
improvements to AGi32, will provide more thorough climate based daylight
modeling capability to more users, and that this practice will find its
way into the emerging daylight quantity and quality metrics, and building
rating systems.

- Rob G.

···

On Tue, May 25, 2010 12:35 pm, Cramer Silkworth wrote:

Hi All,

Has anyone out there done any daylight modeling for LEED projects? We're
considering it, but wondering about how the LEED process affects things.
Perhaps the glazing factor option is the way to go, instead of full-on
modeling? And what about this sky condition, clear skies at noon on the
equinox...including direct sun? Really? Not daylight factors under the
CIE 10k? Sure, neither are perfect, but...

Thanks,
Cramer
--
*Cramer Silkworth
212 219 2255 | [email protected] <mailto:[email protected]>
Transsolar Inc. | 134 Spring Street Suite 601 | New York, NY 10012

Transsolar Climate Engineering
Technical consulting for energy efficiency and environmental quality in
buildings.
New York - Stuttgart - Munich*
_______________________________________________
Radiance-general mailing list
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http://www.radiance-online.org/mailman/listinfo/radiance-general

===================
Rob Guglielmetti

3

Hi Cramer,

It all depends on the complexity of the spaces. The corporate HQ project I
mentioned some time ago looks like it will meet NC 2.2 Platinum
requirements. We've got Tim Metcalf at Kalwall doing the LEED NC2.2
Daylight modeling as we speak (they keep their glazing properties
proprietary for the skylights). It is a ca. 1972 2 story Federalist box
which is redesigned with a lot of curtainwall, two central atria with
Kalwall roof skylights to supplement the perimeter offices with punched
windows. Glazing Factor doesn't work in our case because there are a
variety of openings that interact with the interior spaces (and it is
conservative, no bounce). Option 3 (measurement) looks like it might work
based on some preliminary test I did at the site, but who it is time
consuming and problematic near the great Lakes around the equinoxes. I'll
let you know what the modeling tells us.

How's it going?

Regards,

Gary

···

On Tue, May 25, 2010 at 2:35 PM, Cramer Silkworth <[email protected]>wrote:

Hi All,

Has anyone out there done any daylight modeling for LEED projects? We're
considering it, but wondering about how the LEED process affects things.
Perhaps the glazing factor option is the way to go, instead of full-on
modeling? And what about this sky condition, clear skies at noon on the
equinox...including direct sun? Really? Not daylight factors under the CIE
10k? Sure, neither are perfect, but...

Thanks,
Cramer
--
*Cramer Silkworth
212 219 2255 | [email protected]
Transsolar Inc. | 134 Spring Street Suite 601 | New York, NY 10012

Transsolar Climate Engineering
Technical consulting for energy efficiency and environmental quality in
buildings.
New York - Stuttgart - Munich*

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

4

Cramer,

I posted a critique of the clear sky option in LEED (and others) here:

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

As you will see, it's more than a little problematic.

-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)

[email protected]
http://www.iesd.dmu.ac.uk/~jm