[Bldg-sim] How have you approached... (UNCLASSIFIED)
Shaun Martin
smartin at shaunmartinconsulting.com
Wed Jul 20 09:20:25 PDT 2011
Hi Nick,
To keep it simple, I would just derate the schedules, your 10/15% reduction
but on an hourly basis (ie one or more hours are moved to 0%/setback) and
apply the RESET-PRIORITY and MIN-RESET-FLOW keywords. I think averaging it
out beforehand and explaining as part of your modelling methodology in your
report would take less time and be easier to explain. I would start with a
small test model, to make sure you have the right percentages.
Shaun
Shaun Martin LEED AP
Principal
Shaun Martin Consulting
Suite 200 - 420 West Hastings Street
Vancouver BC V6B 1L1
604-789-1095
<blocked::mailto:smartin at shaunmartinconsulting.com>
smartin at shaunmartinconsulting.com
member CAGBC, ASHRAE
_____
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Wednesday, July 20, 2011 8:45 AM
To: James Hansen; Eurek, John S NWO; David Eldridge;
bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] How have you approached... (UNCLASSIFIED)
Thanks so much for the suggestions!
I myself have tread the "extensive, realistic fractional/thermostat
scheduling" path before under similar circumstances. Upon facing a VERY
large project, where the amount of explicit scheduling required for that
approach is compounded by the sheer quantity and variety of occupied spaces
benefiting from this relay setup, I am challenged with brainstorming any
acceptable (by LEED reviewer) means of approximating the same
behavior/savings by simplifying the problem.
Here are some alternative ideas we've come up with so far - I would very
much appreciate others' thoughts on these, or any further related LEED/USGBC
experiences to share as well:
1. 90.1 already prescribes how we quantify the savings of occupancy
sensors for installed lighting (10 or 15% flat deduction on the LPD).
Rather than define & justify the quantity and timing of unoccupied hours
between varying space types (murky waters at best), one could instead reduce
the loads incident on the affected systems by the same percentage. This
might be accomplished by applying this 10/15% deduction to the affected
spaces' fractional load schedules (occupancy, equipment & lighting). One
would need to tread carefully to avoid "double-dipping" on any spaces
already claiming a LPD deduction for occupancy sensors. Baseline model's
schedules would remain unaffected and would be documented alongside the
modified ones to illustrate the difference.
2. (Simpler to model, but requiring slightly more documentation):
Let's say a hospital has an annual average of 85% occupancy for all its
patient rooms. Treating every other room normally, select a representative
sampling (considering envelope loads) of 15% of the patient rooms. Model
those selected rooms as "empty" (set people, lights and equipment loads = 0)
but still conditioned to maintain the thermostat setpoint (against loads
incident from the envelope & neighboring spaces). Apply the 0% minimum
turndown behavior to those "empty" rooms only. Baseline model would receive
identical treatments, excepting the 0% turndown behavior. Documentation
would include illustrating which zones were sampled against the others, and
justification for the net annual "occupancy rate" used for each space type.
I have mixed feelings - obviously any simplification of the problem has the
potential to under/overstate the savings that might be found with a more
exhaustive scheduling approach, but may result in as good or even a better
estimation provided with solid documentation and execution. Does anyone
think the above approaches could work well, or have any suggestions to
refine the strategies?
Thanks again!
~Nick
cid:489575314 at 22072009-0ABB
NICK CATON, P.E.
SENIOR ENGINEER
Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com
-----Original Message-----
From: James Hansen [mailto:JHANSEN at ghtltd.com]
Sent: Wednesday, July 20, 2011 8:40 AM
To: Eurek, John S NWO; Nick Caton; bldg-sim at lists.onebuilding.org
Subject: RE: [Bldg-sim] How have you approached... (UNCLASSIFIED)
I agree with John, I've done this on a model before and its painful.
Assuming there are 10 hours in a work day, I set up 10 different occupancy
and lighting schedules, each schedule being essentially identical except for
a different hour of zero occupancy / lighting. I then applied these 10
schedules to the different office zones on a floor so that specific areas
were vacant from 8am-9am, some vacant from 9am-10am, etc. And then for my
system, I assumed relatively consistent 10% non-occupied conditions and
reduced the OA at the system level accordingly. If your non-occupied
conditions are more drastic (30%), obviously you can set up your schedules
differently.
However, if your primary air is also cooling (and not some sort of DOAS
chilled water VAV box), then you are going to also have to specify 10
separate thermostat schedules (really 20 with heating and cooling) so that
the rooms do not have unmet load hours. I'm assuming you go into setback
mode when the offices are unoccupied.
However, this was under v2.0, so that was a long time ago and reviewers were
not as critical in their reviews.
GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
1010 N. Glebe Road, Suite 200
Arlington, VA 22201-4749
703-243-1200 (office)
703-338-5754 (cell)
703-276-1376 (fax)
www.ghtltd.com
-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Eurek, John S
NWO
Sent: Wednesday, July 20, 2011 9:31 AM
To: Nick Caton; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] How have you approached... (UNCLASSIFIED)
Classification: UNCLASSIFIED
Caveats: NONE
Nick,
I would do it with schedules. This would be the long method.
I have the same controls and have not got around to model it. I would also
make many schedules. A different schedule for occupancy, lights, equipment,
ect. Also if this applies to a lot of rooms, you'd likely make multiple
schedules, one assuming that the room is empty from 9~10 another room empty
from 2~3. (The inverse for meeting rooms, if you have multiple meeting
rooms, not all meetings will happen at the same time.)
"Is Freedom a small price to pay to stop Global Warming?"
John Eurek PE, LEED AP
Mechanical Engineer,
-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Tuesday, July 19, 2011 3:59 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] How have you approached...
I have a precedent question for everyone... this is not a "how to"
procedural
question for any particular software, but to simply feel out what has worked
for others in the past:
Here's a quick description of the situation at-hand: a VAV terminal unit
with a "normal" minimum damper position (say, 30%) is tied by relay to the
space occupancy sensor, which also controls the lights. Upon sensing space
vacancy, the minimum airflow damper position is reset to 0% (airflow is
permitted to stop, provided thermostat temperature set point is satisfied).
Upon sensing occupancy, the preset minimum damper position is restored.
For LEED/USGBC-reviewed energy models, can anyone relate success in modeling
this or a similar energy-saving behavior in the proposed model, distinct
from
the baseline? If so, what approach did you use to model this behavior
and/or
quantify the energy savings?
I was discussing the possibilities with some colleagues and have a few ideas
for approaches that might all be justifiable, ranging from simple (and
quick)
to complex (and time-consuming).
There are likely multiple "right" answers here, but I am hoping to identify
some precedent to understand what we can anticipate the LEED reviewership
will accept.
Thanks in advance!
~Nick
cid:489575314 at 22072009-0ABB
NICK CATON, P.E.
SENIOR ENGINEER
Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com
Classification: UNCLASSIFIED
Caveats: NONE
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