[Bldg-sim] Exterior Lighting Power Calculation for Building Facades

[Robby Oylear]

Yes, due to the fact that I didn’t want to claim unfair credit over the
baseline I only considered a very small portion of the wall to be “lit”.
This caused my baseline allowance to be lower than my proposed which set
off a red flag for the LEED reviewer due to Exterior Lighting Power
density being a mandatory provision of ASHRAE 90.1-2004.



Robby Oylear, LEED® AP

Mechanical Engineer

direct: 206.788.4571

cell: 206.354.2721

www. <http://www.rushingco.com/> rushingco.com



From: Carol Gardner [mailto:cmg750 at gmail.com]
Sent: Thursday, February 04, 2010 5:35 PM
To: Robby Oylear
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Exterior Lighting Power Calculation for Building
Facades



I would divide the 500 Watts by the entire 100 lineal feet of the wall the
fixture is on. I don't see what you would gain by just considering the lit
area of the wall but I can see where you might be penalized. Since it's
just an exterior load there aren't any interactive effects to worry about
either.

Carol

On Thu, Feb 4, 2010 at 8:21 AM, Robby Oylear <robbyo at rushingco.com> wrote:

Can anyone with experience showing compliance with ASHRAE 90.1-2004
section 9.4.5 enlighten me as how the baseline calculation should be done?




The confusion I’m having is with the definition of an illuminated wall or
surface length when applying the 5.0 W/linear foot allowance for building
façades.  How is the lineal footage of an illuminated wall determined?



For example, if a 100’ wide wall has one exterior lighting fixture on it
at the center, is the entire wall considered to be illuminated and thus
the baseline lighting power allowance is 500W?  Or is there some method of
determining the actual portion of the wall that is illuminated?



This came up on a LEED project where I had applied table 9.4.5 as
conservatively as possible and only considered a portion of the wall to be
illuminated at each fixture.



Any help would be greatly appreciated.



Robby Oylear, LEED® AP

Mechanical Engineer

direct: 206.788.4571

cell: 206.354.2721

www. <http://www.rushingco.com> rushingco.com






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