[Bldg-sim] Low Ambient Strategy questioned in LEED Review
Nick Caton
ncaton at smithboucher.com
Thu Nov 17 11:44:29 PST 2011
Karen,
I agree completely, for what it's worth!
In my response (pasted below for continuity), I wasn't thinking
specifically about how this gets applied in baseline vs. proposed, but
focusing on other issues within the comment. I think making a
distinction between "plug loads that are an integral part of the
lighting system" and otherwise makes sense (desk lamps could fall in
either category). Better to not call these process loads at all, to
avoid confusion.
My master's thesis/research was focused on exploring/evaluating
task-ambient lighting strategies and their effects on occupants
comfort/productivity, so it's an issue I'm intimate with as a lighting
designer =).
Thanks!
~Nick
NICK CATON, P.E.
SENIOR ENGINEER
Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Karen
Walkerman
Sent: Thursday, November 17, 2011 11:38 AM
To: Carol Gardner
Cc: bldg-sim at lists.onebuilding.org; Tom Butler
Subject: Re: [Bldg-sim] Low Ambient Strategy questioned in LEED Review
Nick,
I mostly agree with your approach, however I disagree on one point -
even though desk lamps may be plugged-in and not permanently installed,
if they are part of the overall lighting plan, then I think that they
should be included in the proposed model and not in the baseline. If
you have low footcandles in a space, but for whaterver reason, task
lighting is not required (this architectural studio uses giant
multi-touch computers for drawing), then task lights should be modeled
equally in both models.
--
Karen
From: Nick Caton
Sent: Thursday, November 17, 2011 10:40 AM
To: 'Carol Gardner'; Tom Butler
Cc: bldg-sim at lists.onebuilding.org
Subject: RE: [Bldg-sim] Low Ambient Strategy questioned in LEED Review
Tom et al:
To your reviewer's first paragraph... this is something of a tangent for
your quandary, but it sometimes infuriates me how many in our industry
try to apply/enforce/design around the recommended illuminance level
tables without reading the (short!) chapter discussing what they mean
and how they're intended to be used and not used. They are emphatically
NOT "minimums." I have been cornered on this a few times by select
individuals outside of a LEED review - suffice to say reviewers who
don't learn what they're enforcing run the risk of demonstrating their
incompetence.
It appears: (1) your reviewer does not understand task-ambient lighting
and could use some education in that dept and (2) you have not
communicated exactly what that 20fc figure means. Your reviewer has the
impression task surfaces will only have 20fc after all sources (which
would be bad lighting for an architecture studio). Correct that
impression, and further explain how the targeted illuminance values are
going to be achieved.
"Installed interior lighting power" is a 90.1 glossary term. For
90.1-2004/2007, it only includes "permanently installed" fixtures*.
Reviewer is having a quibble over vocabulary... If I'm not mistaken,
desk lamps are plug loads, and plug loads are process loads. Simple.
Perhaps different terminology is part of any revisions you may need to
make. I think the term "process lighting" is something your reviewer
may be making up, but he/she is referring to lighting integral to
refrigerator casework and such in that long list of exceptions... you
should not need to "exempt" desk lamps because they're not permanently
installed and so inherently are not part of "installed interior lighting
power" to begin with.
9.6.3(b) is for VDT's (computer screens) - sorta confusing reference...
Does anyone know if there is precedent for this? The function of this
passage as I understand it is to permit additional lighting beyond the
interior lighting power allowance under the space-by-space method... not
to limit task lighting within the allowance. Again, I think the term
"task-ambient" is throwing your reviewer off.
I have not attempted documenting this myself, but am not aware of
anything in 90.1 or the IESNA Handbook that disallows the use of
non-permanently installed lighting (however variable it may be in a
college setting) to achieve the targeted illuminance values. This may
warrant some investigation however to be sure.
~Nick
* I haven't reviewed 90.1-2010 thoroughly, but it appears revised in
this regard.
NICK CATON, P.E.
SENIOR ENGINEER
Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com
On Thu, Nov 17, 2011 at 4:36 AM, Carol Gardner <gems at spiritone.com>
wrote:
tb,
After, you have read through this couple of times, or looked at it in
an Excel table, you will figure out the changes you have to make and
make them. Always remember, do the proposed case first and then back out
the baseline, which must meet the applicable code.
I think in a case like this building you would have had a different
result if you had attached, or put into the form, what you were trying
to do and how you did it. Your explanation is quite good and it gives
the reviewers something to look at besides numbers. Then you get to
exercise both sides of your brain.
Cheers,
Carol
On 11/16/2011 10:26 PM, Tom Butler wrote:
Sorry for the long attachment here, but this LEED v2.2 EAc1
comment has me really confused so I want to post it in its entirety.
1. The EAc1 Narrative describes the interior lighting design
target for all studio spaces is 20 fc and that task lights have been
modeled identically in the Baseline and Proposed case. However,
according to the IESNA Lighting Handbook, ninth edition, the minimum
horizontal design illuminance for art studios is 50 fc and for reading
areas with handwritten tasks is 30 fc. The ASHRAE allowances represent
the power allowance required to meet the minimum IESNA illuminance
requirements for various space types. It is inappropriate to claim
savings for designs that do not meet the minimum lighting level
requirements and model the additional lighting power in the Baseline for
lighting in the Proposed that is required to perform the anticipated
tasks.
Also, Table 1.4 reports that 4.02 kW of process lighting has
been modeled in both cases, and it is assumed that this represents the
task lighting. Process lighting is limited to the exempt interior
lighting applications described in Section 9.2.2.3. Task lighting is
regulated and thus not considered a process load. Section 9.6.3(b) does
provide an additional allowance for task lighting when the Space by
Space Method is used, but this may not be used for lighting required to
raise the ambient lighting to meet the required lighting levels. If this
additional allowance is used in the Proposed design, the Baseline must
be modeled with the same power as the Proposed up to the 0.35 W/square
foot allowance. Please remove all task lighting power from the Baseline
model that is required to meet the IESNA recommended illuminance levels.
If any of the additional allowance from Section 9.2.2.3 is applied to
the Baseline case, provide calculations verifying that this additional
lighting is not required in the Proposed case to meet the required
illuminance levels and confirming that this only represents the portion
of the additional allowance that is used in the Proposed case.
My first question; isn't low ambient-task specific a commonly
accepted energy use reduction strategy? Why would I model a lighting
design in the proposed solution which isn't installed and how would one
determine, without an extensive lighting design effort, the appropriate
lighting power to achieve 50fc, or 30fc? (not quite sure which one they
want)
Second, the spaces in question are architecture college studios.
If the task lighting is a plug in desk lamp, provided by the student,
then am I correct in assuming it's not regulated by 9.2.2.3? I've
assumed 60W per lamp as plug load, but there no way that the lamp type
or light distribution can be controlled as defined in 9.6.3.b, nor is it
a given that a lamp will be used.
I'm at a loss as to how to respond to this.
Thanks for any input.
tb
Tom Butler
Residential Green Building Services Project Manager
Tel: 404-604-3635
Fax: 404-872-5009
Email: tbutler at southface.org <mailto:amcfarland at southface.org>
Web: www.southface.org <http://www.southface.org/>
241 Pine Street NE, Atlanta, GA 30308
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