[Radiance-general] Current practice for LEED sky modelling?

[Guglielmetti, Robert]

Yeah, the LEED "clear sky" absolutely means a clear sky with a sun (unless
they've changed it recently in LEED). ALL of my clear sky simulations with
Lightscape, AGi32, and Radiance over the years have included the sun.
After all, aren't we trying to predict daylight performance??

Hey Chris, when'd you move to New York? Congrats, and enjoy the humidity.
=8-)
 

Rob Guglielmetti  IESNA, LEED AP
Commercial Buildings Research Group
National Renewable Energy Laboratory
15013 Denver West Parkway MS:RSF202
Golden, CO 80401
303.275.4319
robert.guglielmetti at nrel.gov





On 6/19/12 7:16 AM, "Chris Coulter" <Chris.Coulter at burohappold.com> wrote:

>Lars,
>
>I have done several LEED compliance calculations in the past using clear
>sky with sun (+s as the gensky parameter). This allows for daylight
>redirecting devices to push light further into a space, and more
>recently the requirement for glare control above 500fc.
>
>My take is that the phrase "clear sky" does not mean "clear sky without
>sun" as might be mistaken in general radiance terms. I've always assumed
>the sun is included.
>
>None of our submitted calculations have been questioned to date, so
>assume that this is acceptable.
>Hope this helps!
>
>Cheers.
>
>Chris Coulter
>Senior Lighting Designer
>Buro Happold Consulting Engineers
>100 Broadway, 23rd Floor
>New York, NY 10005
>Tel: 212.334.2025
>Direct: 212.616.0254
>Email: chris.coulter at burohappold.com
>Website: www.burohappold.com
>
>-----Original Message-----
>From: Lars O. Grobe [mailto:grobe at gmx.net]
>Sent: Tuesday, June 19, 2012 4:21 AM
>To: Radiance general discussion
>Subject: Re: [Radiance-general] Current practice for LEED sky modelling?
>
>Hi John,
>
>I am aware of that really nice overview. The critique of using an
>impossible sky model is hard to question. Excluding the sun also means
>that any technique  to make use of direct sunlight by e.g. redirecting
>it deeper from the perimeter into the building is not accounted for at
>all. So that is why I was wondering how folks doing their real-life jobs
>for LEED are handling the problem with the current standards in mind.
>
>Another question is whether direct sunlight, after it got redirected, is
>still direct sunlight in LEED terms.... or whether redirected means
>indirect here and I could again include it... leaving me with a more
>meaningful sky model (clear sky with sun, and only portions directly
>entering the used spaces being locked out assuming users would block
>them by sunshades) accounting for redirecting facades.
>
>I am not sure wether this is too much LEED-specific for the mailing
>list, but I was really curious how Radiance folks is working around the
>not-so-physically-based specifications of current LEED when setting up
>simulations.
>
>Cheers, Lars.
>
>> There's a critique of daylight modelling for LEED and other codes
>here:
>>
>> http://www.iesd.dmu.ac.uk/~jm/doku.php?id=academic:daylight-compliance
>>
>> It includes a discussion on sky models.
>>
>> Best
>> John Mardaljevic
>>
>> Reader in Daylight Modelling
>> Institute of Energy and Sustainable Development De Montfort
>> University, The Gateway, Leicester, LE1 9BH, UK
>> Tel: +44 (0) 116 257 7972
>>
>> jm at dmu.ac.uk
>> http://www.iesd.dmu.ac.uk/~jm
>> http://dmu.academia.edu/JohnMardaljevic
>
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