[BLDG-SIM] Process Loads and LEED

Varkie Thomas thomasv at iit.edu
Tue Mar 6 09:23:02 PST 2007


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



From: "Brandon Nichols" <BrandonN at Hargis.biz>
Reply-To: BrandonN at Hargis.biz
To: <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




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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