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

[weixiu kong]

I agree with Carol. If your exterior lights are evenly placed along the wall, you may use the entire length to calculate allowances. This is to show compliance. In your energy model, your base line should be the same as the proposed design, because it is a non-tradable surface and you can't claim savings. Also you can't claim benefit for other categories that don't comply with the code.

Thanks,

Weixiu




________________________________
From: Robby Oylear <robbyo at rushingco.com>
To: Carol Gardner <cmg750 at gmail.com>
Cc: bldg-sim at lists.onebuilding.org
Sent: Thu, February 4, 2010 7:39:02 PM
Subject: Re: [Bldg-sim] Exterior Lighting Power Calculation for Building Facades


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.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.rushingco.com
 
 

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