RE: [EnergyPlus_Support] Process loads below 25%

Let me see if I can add some clarity to the reasoning behind the 25% process rule.

First of all and most important � every project should model what has been designed/built and nothing more.

The 25% value was selected since that is a pretty typical plug load percentage for an office building (LEED was originally created for an office building and there are still vestiges of this lineage). This value was never intended as a hard and fast minimum for all projects. The intention was to make sure that all energy uses in any building were accounted for in the model, unfortunately it has been widely misunderstood. This is an indication that we have a problem in the LEED credit language. LEED 2012 is likely to drop this �requirement�.

The 25% had nothing to do with raising the level of difficulty. We clearly understand that facilities with high process energy loads have a harder time earning points in LEED than those with low loads. This is a problem for many LEED projects and USGBC is slowly adding baselines for process loads so energy savings can be claimed against them.

One should NEVER add non-existing loads to get up to 25%. This is completely counter to the intention of this rule.

If you are under 25% James has it correct, simply document what you have. Most typically this would include a spreadsheet and perhaps a narrative if anything would need to be explained so the reviewer can understand the situation. In the vast majority of cases this information should exist as it is often needed in order to perform the HVAC load calculations correctly. So I don�t really understand the perceived difficulty. For many building types with only plug loads as process one can also use the W/sf values in the 90.1 Unser�s Manual.

It is the intention of USGBC to make sure that the energy model addresses all of the energy in and associated with the project. This was the intent of the 25% rule. This language is in the credit requirement but its connection to process energy is certainly not clear.

As a company that was one of the original 5 review firms, our reviewers will question a project whose process energy is exactly 25%. This gives the appearance that either non-existing loads have been added or even worse that process loads have not even been included in the models and a value equating to 25% was added to the modeling results. Again model what you have. If over 25% do nothing. If under 25% document why.

Always keep in mind that the purpose behind modeling is to guide design-decisions and to the greatest extent possible accurately project the actual energy consumption of the facility. Under the USGBC�s Building Performance Initiative and MPR #6 in LEED 2009, your modeling results will be compared to the actual building�s energy use (although this comparison will not be made public on an individual project basis) so every effort to improve quality and accuracy should be taken.

Marcus Sheffer, Chair USGBC EA TAG

Energy Opportunities, Inc/a 7group Company

1200 E Camping Area Road, Wellsville, PA 17365

717-292-2636, sheffer@xxxxxxxxxxxxxx

www.sevengroup.com

From: bldg-sim-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:bldg-sim-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Nick Caton
Sent: Friday, April 30, 2010 7:31 PM
To: Carol Gardner; bldg-sim@xxxxxxxxxxxxxxxxxxxxx; equest-users@xxxxxxxxxxxxxxxxxxxxx; bldg-rate@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [Bldg-sim] Fwd: [Bldg-rate] LEED+90.1 Process/Plug LoadsConundrum

Firstly, apologies for the cross-posting, but it appears this topic has grown include many lists so I can�t come up with an alternative!

Secondly, a huge thanks to Carol, James and a large number of others (who shall remain unnamed until they should decide to join the public discussion) who have given me direct input on their personal thoughts, outside of the mailing lists.

I have received a flood of suggestions regarding approaches when the intent is to follow the 25% rule, and additionally regarding how one might go about appeasing a USGBC LEED model reviewer when attempting to document a lower figure. My impression up until this point, based on colleagues� experience/advice, has been that attempting to substantiate anything less than 25% process loads would be a futile task and would be flatly rejected. As a result I never really considered this to be an option available to us LEED energy modelers. I now understand that for many, documenting something less than 25% has proven a feasible, if occasionally exhaustive, task.

When the intent is to follow the 25% baseline process load prescriptive requirement, I have been exposed (again outside of the lists) to a surprising number of unique viewpoints and seemingly legitimate approaches which have led to successfully reviewed LEED model submissions for others.

Among the approaches to build the process loads to 25% are:

- Adding a single direct internal/external load to the project electrical meter in addition to the designed space equipment loads � this approach avoids additional internal heat gains.

- Adding additional or redefining designed space equipment loads, adding internal heat sources. If and when these additional loads should result in too many unmet cooling hours in the proposed model, there are two basic approaches:

o Specify larger system cooling capacities and/or airflows

o Allow those systems cooling capacities/airflows to auto-size

- Keeping the designed space equipment loads without adding any further, but modifying their utilization schedules to increase space equipment usage during non-peak cooling hours � this of course adds heat to the models, but avoids unmet cooling hours due to clashes with proposed system cooling capacities.

I sincerely hope Carol and others will not misunderstand� Myself and others do not wish to �game the system,� but we seem to have a variety of viewpoints as to what the intent is for the 25% rule.

If it may help and add to the discussion, my personal opinion leading up to this inquiry has been that the default 25% rule exists simultaneously as a means of normalizing the �difficulty level� of attaining LEED EAc1 points for projects with various actual process loads. Perhaps at some point in time, somebody decided it would be unfair for someone designing a LEED Platinum toolshed with zero process loads to have an easier time of it than some poor sucker trying to get some EAc1 credits for an automotive manufacturing facility with immense process loads?

I will unfortunately be unable to participate in or respond to this topic of discussion for some time as I will be away from my inbox. I very much look forward to gaining a better understanding of how we as a group might come to agree on a �best practice� for this issue. If anyone should currently have access to a relevant CIR that would probably be very useful.

A humble thanks again to everyone,

~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

From: bldg-sim-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:bldg-sim-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Carol Gardner
Sent: Friday, April 30, 2010 5:12 PM
To: bldg-sim@xxxxxxxxxxxxxxxxxxxxx; eQUEST Users List
Subject: [Bldg-sim] Fwd: [Bldg-rate] LEED+90.1 Process/Plug Loads Conundrum

---------- Forwarded message ----------
From: Carol Gardner <cmg750@xxxxxxxxx>
Date: Fri, Apr 30, 2010 at 2:40 PM
Subject: Re: [Bldg-rate] LEED+90.1 Process/Plug Loads Conundrum
To: James Hess <JHess@xxxxxxxxxxx>, Nick Caton <ncaton@xxxxxxxxxxxxxxxx>, Karen Walkerman <kwalkerman@xxxxxxxxx>
Cc: "bldg-rate@xxxxxxxxxxxxxxxxxxxxx" <bldg-rate@xxxxxxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxx> 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 1^st 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@xxxxxxxxxxxxxxxxxxxxx [mailto:bldg-rate-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Nick Caton
Sent: Friday, April 30, 2010 12:55 PM

To: bldg-rate@xxxxxxxxxxxxxxxxxxxxx
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

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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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