[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 Arvinders 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 Users 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 Robbys 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 Im 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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