[BLDG-SIM] RE: Process Loads and LEED

[Varkie Thomas]

Thanks for all the responses.  It does not solve my problem where the proposed process load in this “office” building that I am looking at is more than 60% of the total annual energy use.  Here is a suggested solution.  The proposed process load should be entered in the baseline and proposed models since it affects the heating and cooling loads and the difference in efficiencies of the baseline and proposed systems serving the loads. However, when determining the percent energy savings for LEED certification, the common process load should be removed from both sides.
I apologize for bothering BLDG-SIM subscribers with more questions because of my ignorance.
A high process load offsets the heating load in the perimeter zones and you can get a building in a cold climate with no heating.  If the perimeter zone is reduced to 1 foot with no process loads, people or lighting, then the computer program will not account for the benefit of day-lighting on the lighting system unless the program can ignore this perimeter zone and apply day-lighting to the adjacent zone if it is separated by an “AIR-WALL” (DOE2.1E).  
The building that I am looking at has ceiling PIU boxes designed to serve a less than 1 foot perimeter zone and UFAD PIU boxes serving the interior zone.  Both sets of PIU boxes are served by the same system.  In this building, the glass height is 12 feet and the ceiling height, beyond the 1 foot perimeter zone, is 10 feet.  Since the zone depth entered into the program is 15 feet and has a 10 foot ceiling, eQUEST flags it down as an error but not DOE2.1E.  Perhaps VisualDOE will not call this an error.
How would you turn off the Airside Economizer in a DOE2 based program.  With TRACE700 you can say Yes or No.  Climate zone 3A does not require and airside economizer for the baseline for a large office building.  Setting the “Drybulb High Limit” and the “Economizer Low Limit” in eQUEST to their maximum values of 80F seems to do the trick.  I cannot find the Waterside Economizer in eQUEST although the keywords and commands for modeling this, exists in both DOE2.1E and DOE2.2.
How is the Zone-Fan-Ratio (ZFR) determined for Fan Powered Terminal Boxes?  In eQUEST the default for Series FPB is 1.0 and for Parallel it is 0.5.  How was this determined.  The definition in the DOE2.2 manual is:  ZFR * Primary CFM = FPB Supply CFM.  
In the case of the project I am looking at (a UFAD system with Parallel FPBs) the Primary Air Temp is 48F (for dehumidification), the FPB Supply Air Temp = 65F and Recirculation Air Temp is 78F.  What is the ZFR?  Would an increase in ZFR reduce the energy use.  The Simulation Guidebook by Energy Design Resources suggests putting 25% of the people and 33% of lights and equipment in the ceiling plenum.  This produced very little in energy savings.  
Is this an acceptable solution:
Summer Cooling Indoor Temp:  From 0’ to 7’ at 75 F.  From 7’ to 10’ at 85 F   Average Temp = 78 F.  (0.7*75) + (0.3*85) = 78
Winter Heating Indoor Temp:  From 0’ to 7’ at 72 F.  From 7’ to 10’ at 62 F   Average Temp = 69 F.  (0.7*72) + (0.3*62) = 69
(As with the theoretical method of moving internal loads to the plenum, the fact that hot air collects at the top should be not an issue since we are looking at heating only the mass of air from 0’ to 7’ to 72 F).
How would you account for the energy savings using ECM motors.  One suggestion is to reduce the energy use of the fans in PIU boxes by 25%.  The default KW/CFM in eQUEST is 0.00033 (0.33 kw for a 1000 cfm box).  Reducing this by 25%  produced almost no energy savings using eQUEST.
According to the Code of  Federal Regulations (10CFR435/436) occupancy based lighting sensors can be modeled by reducing the lighting schedule/profile fraction by 30%.  Is this acceptable to LEED?  I am assuming that occupancy based ventilation can be modeled by creating a MIN-AIR-SCH (DOE2.1E) that is equal to the design OA fraction (from a trial run) multiplied by the occupancy schedule fraction.
The energy program developers should provide guidelines for modeling energy conservation measures using their programs.  Code and LEED authorities should test them and approve them.
 
----- Original Message ----- 
From: Mike Tillou <miket at etcgrp.com> 
Date: Tuesday, March 6, 2007 4:21 pm 
Subject: RE: [BLDG-SIM] Process Loads and LEED 
To: thomasv at iit.edu, BLDG-SIM at gard.com 


I went back and looked at the public review version of LEED 2.2 dated December 2004 on the cover and October 19 in the footer.  Here is how the original credit was proposed:
"Must be compared against a baseline building that both complies with Appendix G to Standard 90.1-2004 (without amendments) and that has a process energy consumption that is a minimum of 25% of the total energy consumption for the baseline building."
In the final version of the the LEED 2.2 dated October 2005 that same verbiage had been changed to 
"Must be compared against a baseline building that complies with Appendix G to Standard 90.1-2004 (without amendments). The default process energy cost is 25% of the total energy"
 I think the intent is that the default process energy cost used in the calculation of LEED credits for V2.2 is a max of 25%.  If your building has 60% process energy you would only have to count that portion of process energy that equals 25% of the total energy.  This would level the playing field for all buildings regardless of how much process energy is used.  If a building uses less than 25% then you have to justify the legitimacy of that claim.  
I think someone should submit a CIR asking whether this is the correct interpretation of the Credit.
Respectfully,
Mike
Michael Tillou, PE 
ETC Group - Energy Engineering for a Sustainable Future 
Ph:413-458-9870 


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