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

[Carol Gardner]

---------- 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" <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] *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
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *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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