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

[Chris Coulter]

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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