[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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