[BLDG-SIM] Process Loads and LEED

[Bill Talbert]

All, 
 
We agree that the MINIMUM default process energy cost is 25%, but that if it is larger than 25%, the entire value shall be considered as part of the Proposed Building Performance (energy cost), and likewise for the Baseline Building Performance (energy cost).  This conclusion is based on clarification that we received for a LEED project that we're working on.  We cannot say why the CIR is not on the USGBC website, but we're following up on that issue.  We also agree that the process energy cost can be less than 25% of the total building energy cost if documentation supports such a claim.  The LEED v2.2 Ref. Guide (p. 174) states that a savings can be shown in process energy cost between the Proposed Building Performance and Baseline Building Performance via Exceptional Calculation Methods.
 
In addition we concur with Varkie on the fact that the inclusion of ALL process energy does "penalize" a building with respect to improving building design and energy efficiency - the apparent intent of EAc1.  According to the LEED v2.2 Reference Guide, "the intent of LEED-NC is to assist in the creation of high performance, healthful, durable, affordable and environmentally sound commercial and institutional buildings." While it is debatable that LEED did not intend to include building types with significant process loads, it does seem unnecessarily exclusive of these building types, because the stated intent is to improve the design and construction of buildings, not processes. In addition, LEED is now considering making a minimum number of energy credits mandatory in a future version, which will virtually exclude certain building types from being certified. It seems that it would be better and more in line with LEED's own stated goals if more buildings were encouraged to become certified even if the process energy used is high in comparison to the building energy used.
 
With that in mind, it does seem appropriate and reasonable that process energy should be accounted for in some manner, especially where the loads affect HVAC equipment capacities and energy costs associated with space conditioning. However, in order to not exclude high process load buildings from certification, it seems more appropriate to only include the costs specific to process energy up to 25% (used because 25% is already identified) of the total energy costs. The additional process energy costs could be reported separately but excluded from the Percentage Improvement calculation unless additional savings were pursued through an Exceptional Calculation.  
 
Yes, it's good that LEED may be used to drive clients to consider more efficient processes, but it appears that a potential consequence of the current approach is to dissuade certain project types from pursuing LEED certification because a high performance building design does not necessarily offset the impacts of a large process load baseline. The focus should be on non-process building efficiency. 
 
Paul Erickson, LEED AP
Bill Talbert, PE, LEED AP
Affiliated Engineers, Inc.

>>> "Marcus Sheffer" <sheffer at sevengroup.com> 3/6/2007 4:11 PM >>>

Hi Folks,
 
By identical it means that the energy consumption should be identical not the percentage of the total.
 
The USGBC certainly did not intend to exclude high process load building types from savings.  It is true that high process load buildings would not be able to attain the higher percentages without addressing the process loads.  It is also true that all energy consumption contributes to environmental issues surrounding energy use, not just the building related consumption.  We therefore felt it was critical to include all energy use.  
 
As we are all aware there are many energy saving options for most process loads.  The problem is the establishment of a baseline for many of these items.  The EA TAG recognizes this as a significant issue and we are discussing ways to address the situation.
 
In the mean time I would suggest that project teams strive to make all building energy systems as energy efficient as possible and follow the exceptional calculation method to show savings for process loads in the LEED certification review process.
 

Marcus Sheffer
Energy Opportunities, Inc/a 7group Company
1200 E Camping Area Road, Wellsville, PA  17365
717-292-2636, sheffer at sevengroup.com
www.sevengroup.com ( http://www.sevengroup.com/ )
 


From:BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Brian Thornton
Sent: Tuesday, March 06, 2007 2:59 PM
To: BLDG-SIM at gard.com 
Subject: [BLDG-SIM] Process Loads and LEED

 
The interpretation of what “default” means is the key.  Since the second provision says that baseline and proposed process loads shall be identical, if the design process loads are 60%, than the baseline should be 60%, unless you ignore the second provision.  
 
If the interpretation of the “default” is that baseline is always 25%* even if the design process is greater than 25%, than the two cited paragraphs are in contradiction in many cases. (*except for the special case of documented process usage less than 25%)
 
I’m not a lawyer, but it seems these need to reconciled so both paragraphs make sense, or are changed. 
 
My guess/hope is that the USGBC did not intend to exclude all high process load buildings from showing savings under EAc1. 
 
Brian
 

ThorntonEnergy Consulting
p. 503-231-6600 f. 503-231-3555
thorntonenergy at comcast.net

 


From:BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of gail
Sent: Tuesday, March 06, 2007 10:47 AM
To: BLDG-SIM at gard.com 
Subject: [BLDG-SIM] Process Loads and LEED

 
The exact wording of the LEED v2.2 requirements may be helpful in moving this discussion forward.  Per LEED EAc1 requirements:

"The default process energy cost (must) be 25% of the total energy cost for the Baseline building.  For buildings where the process energy cost is less than 25% of the baseline building energy cost, the LEED submittal must include supporting documentation substantiating that process energy inputs are appropriate. "
...
"For EA Credit 1, process loads shall be identical for both the Baseline building performance rating and for the Proposed building performance rating.  However, project teams may follow the Exceptional Calculation Method (ASHRAE 90.1-2004 G2.5) to document measures that reduce process loads.  Documentation of process load energy savings shall include a list of the assumptions made for both the base and proposed design, and theoretical or empirical information supporting these assumptions. "

Buildings with 60% process energy cost probably will likely be negatively impacted by these modeling requirements (it is probable that these buildings will have a tougher time showing substantial Percentage Energy Improvement than buildings having only 25% process loads).  However, if the project can demonstrate that energy improvements have been made to the process energy systems versus standard practice, then the energy savings achieved through these process system efficiency measures can be used to document improved Percentage Improvement using the Exceptional Calculation Methodology.  As Leonard mentioned, the process energy will also impact cooling loads substantially, and improvements to the cooling equipment and controls would also help the overall building performance. 

Gail Stranske
CTG Energetics, Inc.

On 3/6/07, Leonard Sciarra <leonard_sciarra at gensler.com > wrote:

Maybe I am naive, and I have not read the NC 2.2 reference guide yet, but process loads would affect an internally load dominated building, ie, my cooling loads would be different hence my equipment selection between a low density office vs a "financial trading floor" type situation. LEED and gaming the system aside, from a real design point they are important, and could affect envelope component selection.

 

Leonard Sciarra,  AIA, LEED ap
312.577.6580 (Dir)
G E N S L E R | Architecture & Design Worldwide
30 West Monroe Street
Chicago IL, 60603  
312.456.0123
leonard_sciarra at gensler.com      

 

 

From:BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Varkie Thomas
Sent: Tuesday, March 06, 2007 11:23 AM
To: BLDG-SIM at gard.com 
Cc: BLDG-SIM at gard.com 
Subject: [BLDG-SIM] Process Loads and LEED
Vaibhav: Your reference makes the situation worse.    
The LEED energy savings rating system using the bottom line percent savings over baseline appears to penalize buildings with high process loads when you also consider LEED-NC Version 2.2 EA Credit 1 page 174 "The default process energy cost is 25% of the total energy cost for the baseline building".  
What has the process energy cost (or the process energy use) got to do with building design related to energy efficiency (architecture-envelope, lighting, HVAC, DHW) except power supply for the process?  The process energy within an office building can vary from 0.5 w/sf  (minimal use of computers and office equipment) to more than 6.0 w/sf for a financial/trading (Wall Street) type of building.  If the baseline process energy is limited to 25% percent of total and the proposed process energy use is more than 60% of the total then does this mean that the building design is energy inefficient and does not qualify for LEED certification?
Process energy could be part of the analysis if there is a baseline standard for various types of computer and office equipment (varies considerably and hard to define and prescribe for the numerous types processes that occur in just office buildings) and the equivalent proposed equipment is more efficient.  This comes under "Exceptional Calculation Method" category along with several other energy efficient building design options such as double-wall buildings for which you get 1 point (I think).
According to LEED-NC Version 2.2 EA Credit 1 page 174 "process energy is considered to include, but is not limited to, office & general miscellaneous equipment, computers, elevators & escalators, kitchen cooking & refrigeration, laundry washing & drying, lighting exempt from lighting power allowance (e.g. lighting integral to medical equipment) and other (e.g. waterfall pumps).  Do all submissions for LEED certification include all this.  At the construction documents submission stage, what is the level of modeling detail that is required regarding floor spaces and zones and all the systems, plant and equipment shown on the drawings and specifications.  Can you use eQUEST, select the type of building, and let the "Wizard" do the zoning and assume most of the baseline data?   I don't think we are all playing the same game, on the same level playing field and using the same rules to show percent energy savings for LEED certification.
I also have some reservations about how various energy saving systems are modeled with different computer programs.  The programs should be studied and compared with the same case studies of different types of buildings with different systems and plants and showing how each program should be used to demonstrate energy savings from different energy conservation measures such as UFAD.  
Building operation data can now be viewed on the web, collected for meaurement & verification (M&V) and can be used to check computer modeling results.  In the case of a M&V project at IIT, the web based control systems show mainly temperatures.  Sub-meters and data loggers should be included in the control specifications so that the performance of the major systems, plant & equipment can be monitored separately and compared with computer results.  At the moment we are comparing the building utility meter reading with the bottom line building energy use calculated by the computer program. 
Process loads do not affect energy code and Std-90 compliance since "percentages" are not involved.  
V.C. Thomas

----- Original Message ----- 
From: Vaibhav Potnis <vaipotnis at hotmail.com> 
Date: Tuesday, March 6, 2007 8:14 am 
Subject: [BLDG-SIM] Process Loads and LEED 
To: BLDG-SIM at gard.com 
However I wanted to point out that for a LEED energy analysis, process energy has to be maintained at 25% of total energy cost of the Baseline Building Performance ( LEED- 2.2 Ref Guide page 182). I prefer taking exceptional calculatins for process energy to simplify the calculations as well as the review.
Hope this helps.

Vaibhav Potnis 
www.greenbuildingservices.com ( http://www.greenbuildingservices.com/ )

From: "Brandon Nichols" <BrandonN at Hargis.biz>
Reply-To: BrandonN at Hargis.biz
To: <BLDG-SIM at gard.com ( mailto:BLDG-SIM at gard.com )>
Subject: [BLDG-SIM] Process Loads and LEED
Date: Mon, 5 Mar 2007 11:05:04 -0800



Varkie,

 

Something we have been noticing in schools lately is a high receptacle load, which we believe is attributable to increased usage of computers, approaching and in some areas exceeding 5 W per square foot -- the kinds of loads I used to figure for "technology intensive" office areas just a few years ago.

 

In researching an energy question for a school today, I came across this web page and case study which I thought was relevant to your question:

 

http://www.energystar.gov/index.cfm?c=power_mgt.pr_power_management

 

http://www.energystar.gov/ia/products/power_mgt/North_Thurston_Case_Study.pdf

 

Essentially they summarize how, by consistently implementing power management on computer monitors and CPUs using a simple utility program, a cost savings of an estimated $15-$30 per computer per year can be realized (on personal workstations I would add, not systems required to be continuously online).  Multiplied across thousands of computers, the bottom line annual savings can be substantial.

 

How to account for this in energy modeling software I have a general idea:

 

1) Assign the baseline receptacle load to "occupied hours"; e.g. 5 W/SF 'always on'

2) Assign a diversified receptacle load schedule to the alternate analyses

 

But quantifying the diversified load schedule is the hard part -- it will no doubt vary significantly depending on the occupancy.  Though not fully developed, this may provide a starting point for one method to reduce process electrical loads in a LEED analysis.

 

 

Regards

 
Brandon Nichols, PE
Mechanical
HARGIS ENGINEERS
600 Stewart St
Suite 1000
Seattle, WA 98101
d | 206.436.0400 c | 206.228.8707
o | 206.448.3376 f | 206.448.4450
www.hargis.biz ( http://www.hargis.biz/ )

From:BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Varkie Thomas
Sent: Monday, March 05, 2007 7:14 AM
To: BLDG-SIM at gard.com 
Subject: [BLDG-SIM] Process Loads and LEED
LEED-NC Version 2.2 page 173 "Optimize Energy Performance" states "Demonstrate a percentage improvement in the proposed building performance -- " and  "For the purpose of this analysis, process energy is considered to include, but is not limited to, office and general miscellaneous equipment, computers, elevators & escalators, kitchen cooking & refrigeration, laundry washing & drying --- "
On page 174 "For EA Credit 1, process loads shall be identical for both the baseline building performance and the proposed building performance"
Assuming the same space process load is used in the baseline and proposed, then a building with a receptacle load density of say 1.0 w/sf will produce a much greater percent savings compared to the same building with a receptacle load density of say 6 w/sf.
Page 173 "must comply with the mandatory provisions (Sections --- ) in Standard 90.1-2004 (without amendments)"  There is no mention of Standards 62 for ventilation & occupancy density or Standard 55 for indoor comfort conditions.  Does this mean that the baseline can be based on the proposed ventilation, occupancy density and indoor comfort conditions?  According to Standard 62-2004 the occupancy density for general office space is 200 sf/P (from 142 sf/P in 62-2001 and I think 100 sf/P earlier).  This produces a low percent system outdoor air and energy conservation measures such as "occupancy based ventilation" and "outdoor air to relief air heat recovery" have little effect.  Std 62-2004 (also Std 90.1-2004 for lighting) provides design criteria for a limited number of space types such as a prison cell (improved from 50 sf/P & 20 cfm/P in 62-2001 to 40 sf/P & 10 cfm/P in 62-2004) .  This makes it difficult to determine baselin e conditions using Std 62.
I am looking at a financial institution building with high occupancy and receptacle load densities.
 ----- Original Message ----- 
From: David S Eldridge <DSE at grummanbutkus.com> 
Date: Monday, March 5, 2007 10:36 am 
Subject: [BLDG-SIM] Process Loads and LEED 
To: BLDG-SIM at gard.com 
Varkie, I can see merits for the 2.1 method and the 2.2 method.  On the one hand, the process loads are to some degree out of our control.  But on the other hand, if you have a building with such massive load density why would the rating system want to exclude all of that energy from sustainable practices?

 

I like the idea of consistency when considering all of the energy for energy optimization, on-site renewables and green power - there are projects out there that might earn fewer EAC1 points under v2.2 than under 2.1.  The percentage savings were changed between the versions so it's hard to say if it is more or less likely to earn a certain amount of EAC1 points - I would be interested to see a summary if the data is available about EAC1 points under v2.1 compared to v2.2.  Probably about the same?

 

For a high load density building like yours - definitely going to be harder.  The only suggestion as far as EAC1 points that I could offer would that if your design has receptacle load at 6 W/ft2 there is probably a significant diversity in that load, maybe it won't turn out as badly as you fear.

 

In regard to ventilation, you are going to use the outside air requirements from the proposed design and apply that outside air quantity to both models.  There isn't a "baseline ventilation rate" - use equal CFM of OA for both models.  Also, OA may be determined from local building codes rather than ASHRAE - that would also apply equally to both models.

 

The one exception would be that Demand Control Ventilation could potentially be used in the proposed model to reduce OA if DCV isn't required prescriptively, and if your minimum OA from code is less than what is required by ASHRAE 62.

Hope this helps!

 

David

 
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