dwelling unit / residential LPDs

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I have reviewed the archives and found a few threads on this topic but
couldn't find either good resolution, or a clear enough string to reply to,
so I thought I would re-post:

ASHRAE 90.1 App G doesn't let you include dwelling units in typical LPD
calcs. They say you need to plug in the same number for both proposed and
baseline.

But you can apparently pursue exceptional calcs to justify any cost savings
in LEED. But you need to show some kind of analysis as to how you chose a
baseline, such as a study or something presumably that shows typical w /sf
for residential.

We have worked very hard to reduce energy use in lighting in a few high-rise
residential projects and would like to be able to receive credit for that on
our energy model.

Has anyone been through this with USGBC and / or know of a good resource for
a baseline w / sf for residential?

In advance, thank you very much. Great forum.

Sincerely,

Joe Snider, AIA, LEED AP

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Hey Joe,

If you're looking to start somewhere... I know the NEC (NFPA 70) lays
out a clear method of estimating dwelling unit lighting loads within
Article 220. It starts off seeming high (3W/SF), but there are heavy
demand factors that vary with the total calc'd load following within the
same article: i.e. first 3,000 @ 100%... 3,000 to 120,000 @ 35% etc...

While I've yet to fall back on the NEC as an energy modeling resource,
I'm unaware of any better direct source for residential lighting
loads... I imagine if you dig hard enough, one of the ASHRAE handbooks
probably has something along these lines as well that might give you a
different sum.

I think ASHRAE Fundamentals does have a clear thing or two to say
regarding what percentage of the lighting load should end up in a space
vs. a plenum when you are talking about different lamp sources
(incandescent vs. CFL...) - something to be aware of if you want to
pursue this avenue.

NICK CATON, E.I.T.

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Joe,

The dwelling units exception in Appendix G applies to "spaces in which
lighting systems are connected via receptacles and are not shown or
provided for on building plans." You say you've worked hard to reduce
lighting energy use, so presumably, you've designed the lighting for the
spaces and it appears on the plans. Therefore, you are justified in
using your actual lighting design for the proposed building model, and
the LPD value for the baseline, which should be 1.1 W/ft2 for living
quarters per Table 9.6.1.

Regards,

William Bishop, PE, BEMP, LEED(r) AP

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Hi Bill,

Thanks for the response. That is actually exactly what we did - and USGBC
rejected it citing a LEED NC 2.2 CIR, even though this is a LEED 2009
project and they are saying old CIRs are not applicable to new projects
anymore.

Their only direction is to plug in 1.1 w / Sf for both sides of the
equation. However, the CIR they reference opens the door for exceptional
calculations, with good justification. What could be more justified than
using the 1.1 w / SF that ASHRAE has for similar spaces?

It is a bit confusing because there seems to be an implication that
somewhere in ASHRAE it dictates using the same numbers for proposed and
baseline for hard-wired lighting in dwelling units. We can't find any
direction to that effect anywhere, which it seems would leave it open to
interpretation.

At this time we are operating under the assumption that we can use the same
CIR they referenced, and therefore use exceptional calcs. Unless anyone
else has any thoughts..

Take care,

Joe Snider, AIA, LEED AP

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If the electrical design drawings show hard-wired fixtures for
residential units, then you can absolutely use the wattage density that
these afford. If a reviewer is commenting in a way that contradicts
this, it may be because the documentation wasn't clear about it. The
only time I've used the default 1.1 W / sq ft for the proposed design of
residential units is when the lighting systems for the bathrooms,
closets, kitchens, etc were hard-wired, but they left the main living
room to be lit by a tenant fixture. In that case, calculate the wattage
density for the whole space based on the actual densities of the
bathrooms, closets, kitchens, etc and 1.1 for the living area. When in
doubt, over-document what you have to make sure the reviewer can clearly
see that most (if not all) of the fixtures are hardwired.

James Hansen, PE, LEED AP

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Joe,

I would agree with your approach. If GBCI is the one referencing the CIR,
then I also would expect they would allow you to reference that same CIR for
your project...otherwise they shouldn't have mentioned it to you.

Also, it is correct that only hard-wired lighting should be represented.
THere is just too much human variable that will plug lamps into every outlet
in the walls, thus increasing the non-installed lighting power. This is
thier argument.

Although it might not offer you formal reference for your situation, you
might also look at ASHRAE STandard 90.2, which is the energy standard for
low-rise and residentail buildings. Maybe you will find something
enlightening in there... You might also have a good argument if you can
reference how Title-24 and California accept residential LPD in thier models
and modeling guidelines.
Good luck and be cautious, through my experience I've found that the GBCI
reviewers are typically not more experieneced than we the simulators.
Remember all they do is review simulation output, they don't always have the
experience in building the models under the contstraints that we are under
as design simulators. It is our purpose as simulators to represent
real-life as best as possible. It is GBCI's purpose to deny our simulation
approaches if it doesn't follow *thier* rules for simulation. (this is only
my opinion from experience.)

Pasha

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That 1.1 W/SF from section 9 doesn't apply to apartment or condo
dwelling units. Residential unit LPD is unregulated. We calculate
savings for residential lighting as an exceptional calculation using a
baseline LPD sited from research (which is kind of all over the place),
and calculate savings for installed lighting systems that provide for
full illuminance in specific spaces in the residential units. The
lighting is scheduled on for 750 hours/ year (from an old LEED CIR).
These calcs have been approved in the past for LEED EAc1 under NC 2.2
and 3.0.

*Aleka Pappas*

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Is there a CIR or something that says that residential LPD is
unregulated?

Table G3.1 is pretty specific about residential unit lighting for the
proposed model (see below):

As long as the lighting is shown on building plans and permanently
wired, you are allowed to use the actual lighting power. I have done
10+ residential projects where we've listed 1.1 W / sq ft for the living
/ bedroom areas for the baseline building, and used the actual density
for the proposed model, and been approved. There certainly isn't
anything wrong with doing it the ECM route, but where, specifically,
does it say you can't take credit for any residential unit lighting
efficiencies?

James Hansen, PE, LEED AP

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There is an exception to the scope of section 9.1.1, for "lighting
within dwelling units". However, in addition to the 1.1 W/ft2 allowance
for hotel/motel guest rooms and dormitory living quarters in the
space-by-space method, there is the 0.7 W/ft2 allowance for
"multifamily" using the building area method (Table 9.5.1). This seems
to be another area where the Standard is vague. Many of my projects have
been dormitories, which do not contain "dwelling units" as defined in
section 3, since the residence spaces don't contain kitchens. So I have
not had to apply this exception yet.

Bill

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The only gray area to me is when the design would only partially provide the
lighting ? i.e. it isn?t a fair comparison for the proposed design at 0.5
W/ft2 if there is some expectation of receptacle-based fixtures to also be
included as supplemental lighting sources.

If the intention is for the proposed design to provide *all* of the
lighting, then I believe it to be fair game. Especially hotel rooms, where
the interior designer will have included receptacle-based fixtures if they
are intended, it should be relatively clear what is included in the initial
fit out.

With apartments or condos I think you are less likely to have the design
intended to cover 100% of the occupied lighting, but if that?s the case for
your projects the standard seems to allow it.

Apartments are further complicated since the kitchen, bathroom, and corridor
lighting is often completely provided, where the bedroom and living areas
may not partially provided. However, the 1.1 W/ft2 (or 0.7 W/ft2 for
multifamily) seems to be for a whole apartment including a weighting of all
the different spaces in a typical apartment. Maybe the 0.7 W/ft2 is
intended to allow for supplemental sources in a living room although this
hasn?t been my take on it.

David

*
*

David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, HBDP

*Grumman/Butkus Associates*

*
*

*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *James Hansen
*Sent:* Wednesday, December 08, 2010 2:43 PM
*To:* Aleka Pappas; equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] dwelling unit / residential LPDs

Is there a CIR or something that says that residential LPD is unregulated?

Table G3.1 is pretty specific about residential unit lighting for the
proposed model (see below):

As long as the lighting is shown on building plans and permanently wired,
you are allowed to use the actual lighting power. I have done 10+
residential projects where we?ve listed 1.1 W / sq ft for the living /
bedroom areas for the baseline building, and used the actual density for the
proposed model, and been approved. There certainly isn?t anything wrong
with doing it the ECM route, but where, specifically, does it say you can?t
take credit for any residential unit lighting efficiencies?

**James Hansen, PE, LEED AP*

*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Aleka Pappas
*Sent:* Wednesday, December 08, 2010 3:25 PM
*To:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] dwelling unit / residential LPDs

That 1.1 W/SF from section 9 doesn't apply to apartment or condo dwelling
units. Residential unit LPD is unregulated. We calculate savings for
residential lighting as an exceptional calculation using a baseline LPD
sited from research (which is kind of all over the place), and calculate
savings for installed lighting systems that provide for full illuminance in
specific spaces in the residential units. The lighting is scheduled on for
750 hours/ year (from an old LEED CIR). These calcs have been approved in
the past for LEED EAc1 under NC 2.2 and 3.0.

*Aleka Pappas*

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A great deal of research related work on this subject can be found beginning
on page 24 of this recent NREL publication:.

http://apps1.eere.energy.gov/buildings/publications/pdfs/building_america/ho
use_simulation_revised.pdf

Covers what I interpret are defendable 'baseline' assumptions for both
multifamily and single family (room by room!) scenarios.

Enjoy!

Chris Balbach, PE, CEM, CMVP, BEMP

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Since lighting inside dwelling units is not in scope of ASHRAE 90.1 (section
9.1.1 exception b), the multifamily allowance in Table 9.5.1 applies to all
areas in multifamily buildings except apartment units (corridors,
stairwells, lobbies, mechanical rooms, etc.).

IECC 2009, which is adopted as state code in many locations, modified
in-unit lighting exception to include apartments (see quote below).

SECTION 505

ELECTRICAL POWER AND LIGHTING SYSTEMS

(Mandatory)

505.1 General (Mandatory). This section covers lighting system

controls, the connection of ballasts, the maximum lighting

power for interior applications and minimum acceptable lighting

equipment for exterior applications.

Exception: Lighting within dwelling units where 50 percent

or more of the permanently installed interior light fixtures

are fitted with high-efficacy lamps.

Because of the change, the multifamily allowance of 0.7 W/SF in IECC Table
505.5.2, which is otherwise aligned with ASHRAE 90.1 Table 9.5.1, now
includes lighting in apartment units in addition to common spaces.

There was a LEED CIR from 3/23/2007 that allowed 2 W/SqFt LPD baseline for
in-unit lighting which we used successfully in several LEED 2.1 submittals,
but I think it would be silly for USGBC to continue allowing 2 W/SF baseline
for LEED 3.0 because is so much worse than many local codes.

I'd use one of the following options for documenting in-unit lighting credit
for LEED 3.0:

a) Use 0.7 W/SF in-unit lighting in the baseline model. In the proposed
model, keep this allowance unchanged for areas with no hard-wired lighting
(living rooms, bedrooms, etc.), and use the actual LPD for areas where
lighting is specified (kitchens, bathrooms, etc.). Reference IECC in LEED
submittal as the source for the baseline.

b) Use 1.1 W/SF baseline based on LPD for Hotel/Motel/Dormitory from
Table 9.6.1. In proposed design, keep 1.1 W/SF for areas with no specified
lighting, and use the actual LPD for areas where lighting is specified.

c) Use LPD for spaces of appropriate type from Table 9.6.1 (restrooms,
corridors, etc.) in the baseline model, and the actual specified lighting
in the proposed design.

Either way you go, you should watch for situations when specified lighting
is intended only for part of the room. For example, if there is a hard-wired
fixture in the dining area of dinging/living room, you should not assume
that this will be the only fixture in the space when calculating proposed
LPD.

Maria

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Wow. Fantastic dialogue everyone, and greatly appreciated.

It sounds like the strategy we used has been approved on multiple projects
in the past, but in our case has been denied.

To recap, we did Space-by-Space Method, using 1.1 w/sf for baseline in
living / bedrooms and our specific hardwired fixtures for our proposed.

In the denial, reviewer referenced "a CIR" which we can only assume was the
2/23/2007 CIR referenced by some here, and reviewer told us we needed to
model all dwelling unit lighting as 1.1 w/sf for both proposed and baseline
(without distinguishing between plug-ins and hardwireds).

While we feel that our method was pretty reasonable, we'll likely appeal
under that CIR which opens the door for exceptional calculations.

Anyway, something to keep in mind for others in the future. As we all know,
LEED reviews are not created equal..

Thanks again for all of the help. I hope I can reciprocate with as much
value in the future.

Sincerely,

Joe Snider, AIA, LEED AP

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Chris:
?
Thank you for this insight.I have been working Multi Family Housing and such
"defensible" number are rare.
?
John R. Aulbach, PE, CEM

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The NREL report only covers single family or multifamily three stories or
less (see p.12), so a case would have to be made to USGBC that the data is
applicable to larger buildings that are in the scope of 90.1. Low-rise
residential buildings are governed by different codes, for example the new
0.7 W/SF IECC 2009 requirement only applies to 3+ story multifamily.
Residential section of IECC 2009 says 404.1 Lighting equipment. A minimum of
50 percent of the lamps in permanently installed lighting fixtures shall be
high-efficacy lamps.; there is no associated LPD requirement.

Maria

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Dear All,

Could anyone please provide me with Cairo/Egypt weather (.BIN)
file, I searched over the internet but I found nothing.

Best regards,

Ahmed Osama

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