[Equest-users] Demand Control Ventilation - LEED Model

[Bishop, Bill]

Scott,
 
The baseline model ventilation will be constant during occupied hours
and equal to peak occupancy x cfm/person when using "Fraction of Design
Flow" as the OA control method. The proposed model hourly ventilation
rate will vary and will be equal to peak occupancy x cfm/person x hourly
occupancy schedule fraction.
 
Bill
 
________________________________

From: Scott Janssen [mailto:sjanssen at eypae.com] 
Sent: Wednesday, August 11, 2010 10:03 AM
To: Bishop, Bill
Cc: equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Demand Control Ventilation - LEED Model
 
Bill,
 
Thanks for the response.  I'm a bit confused as to how that would reduce
ventilation in the proposed case though if everything is the same
between the two models (same fractions in occ schedules, same space peak
occ, same zone level OA cfm/person).  Am I missing something?
 
Thanks, 
 
Scott Janssen EMIT, LEED(r) AP 
Energy Analyst
 
EYP Energy 
NanoFab East, Suite 1400 / 257 Fuller Road / Albany, NY 12203
T (518) 438 - 1497 / C (518) 421 - 1267 / eypae.com
<http://www.eypae.com> 
 
/ 2009 Best Firm to Work For
 
From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com] 
Sent: Wednesday, August 11, 2010 9:15 AM
To: Scott Janssen
Cc: equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Demand Control Ventilation - LEED Model
 
Scott,
 
Check the equest-users archives since this has been discussed many
times. You are on the right track.
 
You have to use the same occupancy schedule(s) for your proposed and
baseline models. Enter the peak occupancy for your space and then
create/adjust your occupancy schedule so that it fluctuates somewhere
between 0 and 100% during occupied hours, according to how the space is
actually used. If you set your zone-level OA with the same cfm/person
value in both the proposed and baseline, the proposed will decrease the
ventilation during occupied hours based on the fraction of occupancy in
the schedule. Make sure you are not "gaming the system" - your peak
occupancy and cfm/person values that you use should be consistent with
the actual mechanical design peak ventilation rate.
 
Regards,
Bill
 
William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers & Architects
LLP
Mechanical Engineer
 
134 South Fitzhugh Street
Rochester, NY 14608
T: (585) 325-6004 Ext. 114
F: (585) 325-6005
wbishop at pathfinder-ea.com
www.pathfinder-ea.com
P Sustainability - less is more.
________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Scott
Janssen
Sent: Wednesday, August 11, 2010 9:00 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Demand Control Ventilation - LEED Model
 
My question is in regards to setting up the design case model to reflect
demand control ventilation.  So far, I've set the min OA schedules for
the zones to 0 during unoccupied hours to limit OA and set the HVAC
system min OA method to DCV return, and this has shown some savings.
The occupied hours for some of the spaces are roughly 12 hrs/day, but
the spaces will be occupied roughly 1/3 of the time during those hours.
As this project is going for LEED, is it acceptable to adjust the
occupancy schedules in any way to account for the effectiveness of the
DCV system when these spaces are "unoccupied" during occupied hours, or
does anyone have any suggestions for other changes I can make to the
design case model?  This is really an ideal scenario for DCV as the
occupied schedule for the building is long (at least 12 hrs per day),
but the actual occupancy of the building will be sporadic and I'm
concerned that the model isn't reflecting the full-effectiveness of the
DCV system.
 
Thanks in advance, 
 
Scott Janssen EMIT, LEED(r) AP 
Energy Analyst
 
EYP Energy 
NanoFab East, Suite 1400 / 257 Fuller Road / Albany, NY 12203
T (518) 438 - 1497 / C (518) 421 - 1267 / eypae.com
<http://www.eypae.com> 
 
/ 2009 Best Firm to Work For
 
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