[Bldg-sim] [Equest-users] Fwd: [Bldg-rate] LEED+90.1 Process/Plug Loads Conundrum
Chris Jones
cj at enersave.ca
Sat May 1 07:24:27 PDT 2010
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 <<mailto:cmg750 at gmail.com>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
><<mailto:JHess at tmecorp.com>JHess at tmecorp.com>,
>Nick Caton
><<mailto:ncaton at smithboucher.com>ncaton at smithboucher.com>,
>Karen Walkerman <<mailto:kwalkerman at gmail.com>kwalkerman at gmail.com>
>Cc:
>"<mailto:bldg-rate at lists.onebuilding.org>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
><<mailto:JHess at tmecorp.com>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:
><mailto:bldg-rate-bounces at lists.onebuilding.org>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: <mailto:bldg-rate at lists.onebuilding.org>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 @
><http://www.smithboucher.com>www.smithboucher.com
>
>
>
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Chris Jones
14 Oneida Avenue
Toronto, ON M5J 2E3.
Tel. 416-203-7465
Fax. 416-946-1005
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