[Bldg-sim] Exterior Lighting Power Calculation for BuildingFacades

Maria Karpman maria.karpman at karpmanconsulting.net
Fri Feb 5 09:30:12 PST 2010


The intent of the standard seems to not allow lower non-tradable lighting
power in the proposed model compared to the baseline, because this would in
effect make it subject to trade off. Below is an abstract from 90.1 user
manual with the relevant text highlighted in red.  

 

Exterior Building Lighting

Power (§ 9.4.5)

The Standard specifies power limits for

many exterior lighting applications

including parking lots, walkways and

plazas, building entrances and exits,

canopies and overhangs and outdoor sales

areas. For these applications, an exterior

lighting power allowance is calculated for

the entire project and a lighting budget is

established.

Additional power allowances are

provided for other lighting applications

such as building facades, automatic teller

machines, guard stations, drive through

windows and parking near retail

establishments, but these are use-it-or lose-

it allowances and no tradeoffs are

permitted. There is a 5% adder that may

be applied to the exterior lighting power

allowance.

 

 

Maria 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Bishop, Bill
Sent: Friday, February 05, 2010 12:20 PM
To: weixiu kong; Arvinder Dang; Robby Oylear; Carol Gardner;
bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Exterior Lighting Power Calculation for
BuildingFacades

 

I am not a LEED reviewer but I agree with Arvinder’s approach below. Model
the actual exterior lighting design for the proposed model and use the
maximum allowable exterior lighting for the baseline for each surface that
is modeled for the proposed design. From the ASHRAE Standard 90.1-2004 and
2007 User’s Manuals, p G-18:

 

“Other than cases where the lighting is exempted, credit may be taken for
improvements in exterior lighting efficacy or wattage. If the proposed
building does not have an exterior lighting application (for instance a
parking lot that is not lighted), the baseline building shall not have the
exterior lighting application either. If the lighting application exists,
however, then the proposed building can take credit for a more efficient
system.”

 

To answer Robby’s question, I agree with Carol Gardner that for an
“illuminated wall” you should use the entire length of the wall to calculate
the lighting power allowance for compliance with 9.4.5, even if you only
have a single fixture in the center.

 

Regards,

Bill

 

William Bishop, EIT, LEED® AP | Pathfinder Engineers & Architects LLP

Mechanical Engineer

 

134 South Fitzhugh Street
Rochester, NY 14608
T: (585) 325-6004 Ext. 114
F: (585) 325-6005

wbishop at pathfinder-ea.com

www.pathfinder-ea.com

P Please strive to live sustainably.         

  _____  

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of weixiu kong
Sent: Friday, February 05, 2010 11:31 AM
To: Arvinder Dang; Robby Oylear; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Exterior Lighting Power Calculation for
BuildingFacades

 

Arvinder,

 

I got the interpretation from one of the LEED reviewers. And I think it 
agrees with how you show compliance for non-tradable surfaces.

 

Weixiu

 

  _____  

From: Arvinder Dang <Arvinder.Dang at som.com>
To: Robby Oylear <robbyo at rushingco.com>; "bldg-sim at lists.onebuilding.org"
<bldg-sim at lists.onebuilding.org>
Sent: Fri, February 5, 2010 4:38:16 AM
Subject: Re: [Bldg-sim] Exterior Lighting Power Calculation for Building
Facades

Weixiu

Are you sure about your interpretation of the non-tradable surfaces. If I
understand correctly what you are saying is that even though my proposed
design uses less lighting power compared to the baseline for the
non-tradable surfaces I cannot get an benefit from those savings.

 

 My understanding was that total of tradable and nontradable should be less
than the overall allowance +5% additional unrestricted allowance. 

Each category of tradable does not have to comply prescriptively and can be
higher than base allowance in some cases and have increased savings in
another. For example my overall lighting energy use can be higher for say
parking area compared to the base allowance as long as I compensate that
additional power by increased savings in another category say plaza area.

On the contrary one has to meet the prescriptive requirements for each
category of non tradable surfaces and cannot exceed the allowance. Increased
building façade lighting cannot be compensated by reduced gatehouse
inspection station lighting.

 

Can someone please confirm this. 

In my model I have significant savings in non-tradable lighting and I have
been modeling Ashrae allowance for non tradable area based on area being lit
in base case and actually proposed design wattage and lighting power in the
proposed case which is much lower. 

 

Thanks

 

ARVINDER DANG, LEED® AP

SUSTAINABILITY SPECIALIST   

 

SKIDMORE, OWINGS & MERRILL LLP 

224 SOUTH MICHIGAN

CHICAGO, IL 60604 

T: 312.360.4633  F: 312.360.4910 

ARVINDER.DANG at SOM.COM

 

 

SOM

 

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From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Robby Oylear
Sent: Friday, February 05, 2010 5:54 AM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Exterior Lighting Power Calculation for Building
Facades

 

Weixiu,

 

The problem I am having is that I do not understand how to correctly
calculate the baseline power allowance.  Part of the mandatory provisions of
section 9.4.5 states that you cannot exceed the baseline exterior lighting
power allowance with your proposed building.  By incorrectly calculating the
baseline exterior lighting and showing this in my model the LEED reviewer
has flagged my EAp2 credit for denial due to not complying with the
mandatory provisions.

 

In short, I need to reply back with a corrected baseline lighting power
allowance, which I am having trouble with due to the unclear definition of
“illuminated wall”.

 

Robby Oylear, LEED® AP

Mechanical Engineer

direct: 206.788.4571

cell: 206.354.2721

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

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of weixiu kong
Sent: Thursday, February 04, 2010 10:00 AM
To: Robby Oylear; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Exterior Lighting Power Calculation for Building
Facades

 

Robby,

 

My understanding is: since this is a non-tradable surface, base line and
proposed design should be the same even though it is well below allowances.

 

Thanks,

 

Weixiu

 

  _____  

From: Robby Oylear <robbyo at rushingco.com>
To: bldg-sim at lists.onebuilding.org
Sent: Thu, February 4, 2010 10:21:28 AM
Subject: [Bldg-sim] Exterior Lighting Power Calculation for Building Facades

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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