[Bldg-sim] [Equest-users] Fwd: [Bldg-rate] LEED+90.1 Process/Plug Loads Conundrum

Mon May 3 09:14:22 PDT 2010

I use Table E2 from CBECS
(http://www.eia.doe.gov/emeu/cbecs/cbecs2003/detailed_tables_2003/2003set19/
2003pdf/alltables.pdf) to verify that the fraction of process/plug loads is
in right ballpark for various building types.

Maria Karpman

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Marcus Sheffer
Sent: Monday, May 03, 2010 11:37 AM
To: 'Chris Jones'; Carol Gardner; bldg-sim at lists.onebuilding.org; eQUEST
Users List
Subject: Re: [Bldg-sim] [Equest-users] Fwd: [Bldg-rate] LEED+90.1
Process/Plug Loads Conundrum

Unfortunately the reviewer was incorrect in their interpretation for that
review.  GBCI is working hard to ensure a higher level of consistency in
LEED reviews.  The change from the Certification Bodies method to bringing
reviews in-house at GBCI should go a long way to achieving better
consistency.

Also while it does appear that the 25% is being calculated based on energy
use, we have been assured by the author of the form that it is indeed being
calculated based on cost.

Marcus Sheffer, Chair USGBC EA TAG

Energy Opportunities, Inc/a 7group Company

1200 E Camping Area Road, Wellsville, PA  17365

717-292-2636,  <mailto:sheffer at sevengroup.com> sheffer at sevengroup.com

www.sevengroup.com

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Chris Jones
Sent: Saturday, May 01, 2010 10:24 AM
To: Carol Gardner; bldg-sim at lists.onebuilding.org; eQUEST Users List
Subject: Re: [Bldg-sim] [Equest-users] Fwd: [Bldg-rate] LEED+90.1
Process/Plug Loads Conundrum

On one project the reviewer demanded that I increase the plug load cost from
23.5% to 25%.  In my experience, the reviewer always looks for this one as
it is an easy one to point to so the reviewer looks like he/she is doing
their job.

At 06:12 PM 4/30/2010, Carol Gardner wrote:

---------- Forwarded message ----------
From: Carol Gardner <cmg750 at gmail.com>
Date: Fri, Apr 30, 2010 at 2:40 PM
Subject: Re: [Bldg-rate] LEED+90.1 Process/Plug Loads Conundrum
To: James Hess <JHess at tmecorp.com>, Nick Caton <ncaton at smithboucher.com >,
Karen Walkerman <kwalkerman at gmail.com>
Cc: " bldg-rate at lists.onebuilding.org
<mailto:bldg-rate at lists.onebuilding.org> " <
<mailto:bldg-rate at lists.onebuilding.org>  bldg-rate at lists.onebuilding.org>

Hi Nick,

I'm glad you raised this issue. 

First, I agree with James, and have heard from other people, that LEED
accepts documentation saying something as basic as "hey, I don't have 25%
plug loads".

Second, when you have to create a baseline to measure up from, you are
forced to say what that baseline is. For instance, in 1985-86, working on
the BPA-funded Energy Edge project, we had to figure out the baseline for a
group of buildings being designed to exceed the current energy codes by 30%.
We didn't have a baseline then. To deal with this we assembled a group of
people that we euphemistically called The Greybeards (so sorry to you all).
The tables now known as G3.1.1A & G3.1.1B in Standard 90 came out of what we
created in that moment of time. We were trying to limit what is called
"gaming the system"

So now it seems it has been deemed important to control the baseline a
little more: by specifying plug loads at 25%. The goal of trying to limit
gaming the system might be the source of the 25%. The danger which Nick has
clearly demonstrated in his email is that what is meant to control gaming
the system, may now actually be creating it.

Further thoughts/comments welcome,

Carol

On Fri, Apr 30, 2010 at 1:42 PM, James Hess <JHess at tmecorp.com> wrote:

This is a good question.  On prior projects we have worked on, I have found
that you can have less than 25% plug loads, so long as you have some
documentation to back it up.

For example, we are currently working on a prison project.  The plug loads
are very low for obvious reasons; they don't provide stereos, computers,
ipods, TV's, etc. to the inmates (typically, all they get is an alarm
clock/radio that uses ~ < 10 watts).  There is no way on this project that
we could get the plug loads to come in at 25% unless we artificially jacked
them up to levels that would never exist in reality.  We would have a
similar problem in that the Proposed Design equipment would not be able to
cool the spaces.  So, we just document the loads we do have and I believe we
are good.  The project has been through the 1st review and this has not come
up as an issue.  

I believe we have had other projects where we documented the loads we had
and passed the review with no problems.  We will typically develop a simple
spreadsheet and document the internal loads that each room has.  That is
easy enough to do these days I believe, for most applications.  For example,
a typical desktop computer uses about 65 watts on average, monitor = ~ 45
watts (depending on size), clock radio ~ 10 to 15 watts, etc. you get the
point.  (get a "Killawatt" power meter from Amazon and have some fun taking
some measurements to see approximately how much power stuff uses, guaranteed
to provide hours of fun).

Just provide some documentation on some good reasonable estimates for the
loads and I think you will be fine.

An alternate method is to use default values from Table G-B from the ASHRAE
90.1-2007 Users Manual.

For example, the Receptacle Power Density for the Office Building Type is
0.75 watts/SF per Table G-5.

If using that value results in the process loads being less than 25%, my
comment to the reviewers would be that the 0.75 watts/SF is the value
determined by ASHRAE to be appropriate for the building type.

I think the most important thing is to use something reasonable and
defendable, and make it the same between the Baseline and Proposed Design
energy models.  Our experience indicates that it does not have to be exactly
25%, can be less than 25% or greater than 25%, depending on the building.

One thing that is interesting is that on federal projects, per EPACT
requirements, you do not have to factor in the process/recep loads for the
purpose of determining whether the 30% savings requirement has been met.
That makes it easier to show 30% savings.  

Thanks!

Regards,

JAH

James A.  Hess, PE, CEM

Senior Energy Engineer

TME, Inc.

Little Rock, AR

Mobile: 501-351-4667

From: bldg-rate-bounces at lists.onebuilding.org [
<mailto:bldg-rate-bounces at lists.onebuilding.org>
mailto:bldg-rate-bounces at lists.onebuilding.org] On Behalf Of Nick Caton

Sent: Friday, April 30, 2010 12:55 PM

To: bldg-rate at lists.onebuilding.org

Subject: [Bldg-rate] LEED+90.1 Process/Plug Loads Conundrum

Something new occurred to me this week and I'd love to hear others'
thoughts!

LEED prescribes baseline/proposed energy models to follow ASHRAE 90.1 with a
caveat:  the "process energy costs" must total 25% of the baseline energy
costs.  By extension, 90.1 requires the same loads/schedules be applied to
the proposed model as they have to match.  As an aside, the LEED EAc1
templates appear to calculate/check this using process energy consumption
(not cost), but that's not what I'm getting at.

I just had a typical case where I had to inflate the baseline internal
miscellaneous equipment loads to get to 25%.  These additional loads were
substantial enough that when applied to the proposed model/design, I ran
into many unmet cooling hours for the equipment capacities entered.  

Then I realized:  We can define additional equipment electricity loads but
simultaneously apply a multiplier (in eQuest anyway - I expect this is
feasible other programs also) to reduce/negate the corresponding heat load
contributions.  This results in the energy consumption/costs showing up
correctly in the final results/reports, but does not artificially inflate
the internal loads that the baseline/proposed systems must handle.

Would this practice (which incidentally can be a time saver) of accounting
for extra process/miscellaneous loads without extra thermal contributions be
in line with the intent of ASHRAE/USGBC?  It would still normalize the
otherwise unstandardized process consumption/costs of the baseline/proposed
models between different building types.

On the other hand, if it really is the intent of USGBC to add arbitrary
additional internal heat loads to our models that our actual designs were
not designed and sized for, does it follow that we should allow the proposed
models to autosize cooling equipment/fan capacities and not specify them
(this would seem incongruous with 90.1 to me)?

~Nick

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

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