[Equest-users] dwelling unit / residential LPDs

[James Hansen]

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.

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

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

 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Joe
Snider
Sent: Wednesday, December 08, 2010 12:32 PM
To: 'Bishop, Bill'; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] dwelling unit / residential LPDs

 

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

 

---

Joe Snider, AIA, LEED AP

 

SEQUIL Systems, Inc.

high performance sustainable structures

 

1 SE 4th Ave, Suite 205

Delray Beach, FL 33483

t: 561.921.0900

f: 561.208.6090

 

www.SEQUIL.com

 

From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com] 
Sent: Wednesday, December 08, 2010 9:26 AM
To: Joe Snider; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] dwelling unit / residential LPDs

 

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,

Bill

 

William Bishop, PE, BEMP, LEED(r) 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
<http://www.pathfinder-ea.com/> 

P   Sustainability - the forest AND the trees. P 

________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick
Caton
Sent: Tuesday, December 07, 2010 7:16 PM
To: Joe Snider; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] dwelling unit / residential LPDs

 

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

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Joe
Snider
Sent: Tuesday, December 07, 2010 5:24 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] dwelling unit / residential LPDs

 

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

 

---

Joe Snider, AIA, LEED AP

 

SEQUIL Systems, Inc.

high performance sustainable structures

 

1 SE 4th Ave, Suite 205

Delray Beach, FL 33483

t: 561.921.0900

f: 561.208.6090

 

www.SEQUIL.com

 

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