[Bldg-sim] Fan power when changing baseline system per LEED District Energy rules

[Dennis Knight]

Jason,
If the DOAS fan power is what is driving you over the top on your proposed
model, how are you dealing with outside air in the baseline?  If the added
energy consumption for the FCU's handling all of the OA without heat
recovery in the baseline is not offsetting the DOAS fan power then look at
how the FCU fans in the baseline are bing controlled.  I would assume since
it is a residence or dorm the FCU fans have to run 24/7 at constant volume
to handle the required ventilation and the district chilled water and
district hot water (if that is your heat source) have to expend a lot more
energy to treat the ventilation than the DOAS with heat recovery.  Just a
thought.
Dennis


On Thu, Dec 19, 2013 at 10:12 AM, Jim Dirkes <
jim at buildingperformanceteam.com> wrote:

> I agree with Bill.
>
>
>
> *James V Dirkes II, PE, BEMP, LEED AP*
> *www.buildingperformanceteam.com*<http://www.buildingperformanceteam.com/>
> *Energy Analysis, Commissioning & Training Services*
> 1631 Acacia Drive, Grand Rapids, MI 49504 USA
> 616 450 8653
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Bishop, Bill
> *Sent:* Thursday, December 19, 2013 9:35 AM
> *To:* Jason Kirchhoff; bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Fan power when changing baseline system per
> LEED District Energy rules
>
>
>
> Jason,
>
> Per the “Treatment of District or Campus Thermal Energy<http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&cad=rja&ved=0CCsQFjAA&url=http%3A%2F%2Fwww.usgbc.org%2FShowFile.aspx%3FDocumentID%3D7671&ei=1QKzUuWOBsrokAepk4CIBQ&usg=AFQjCNGNhl9-OMruUu0tuqvHX-iHiN9W3A&bvm=bv.58187178,d.eW0>…”
> document, p. 10, “Any system parameters not specifically referenced in
> Table 3 are modeled as specified in Appendix G.” I would say that applies
> to fan power, so your Baseline FCUs should use the System 1 fan power
> Pfan(w)=CFMS*0.3.
>
> Regards,
>
> Bill
>
>
>
> *William Bishop, PE, BEMP, BEAP, LEED AP **|** Pathfinder Engineers &
> Architects LLP*
>
> *Senior Energy Engineer*
>
> [image: webCertified_logo_colorRGB72DPI.jpg]
>
>
>
> 134 South Fitzhugh Street                 Rochester, NY 14608
>
> T: (585) 325-6004 Ext. 114            F: (585) 325-6005
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> bbishop at pathfinder-ea.com <wbishop at pathfinder-ea.com>
> www.pathfinder-ea.com
>
> P   Sustainability – the forest AND the trees. P
>
>
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [
> mailto:bldg-sim-bounces at lists.onebuilding.org<bldg-sim-bounces at lists.onebuilding.org>]
> *On Behalf Of *Jason Kirchhoff
> *Sent:* Wednesday, December 18, 2013 4:12 PM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Fan power when changing baseline system per LEED
> District Energy rules
>
>
>
>
>
> I'm modeling a multifamily building that uses a campus plant for cooling.
> I'm familiar with the USGBC document for modeling DES plants, and am
> currently looking at Option 1, which is an energy neutral purchased chilled
> water plant. Because the building is residential, the normal baseline
> system is System 1-PTAC. The USGBC document says to change this to a 4-pipe
> fan coil in order to make use of the purchased chilled water. Fair enough.
>
> My problem is how to calculate fan power for this new baseline system.
> FCUs are not a normal baseline system, so there's no direction in Appendix
> G. Has anyone come across this before? If so, what did you do to calculate
> the fan power?
>
> For what it's worth, I see three options:
>
> 1) Since I'm replacing System 1, use the formula for System 1,
> Pfan=CFMs*0.3. The resulting fan power is much lower than my proposed,
> which is a bummer, though it's primarily due to 5 DOAS fans that of course
> aren't in the baseline.
>
> 2) Allow TRACE to calculate the fan power using its built-in 90.1
> features. This number comes out much higher than the proposed fan power,
> which is what tipped me off to this issue. I'm currently trying to back out
> how Trace arrived at the fan power it did.
>
> 3) The proposed building uses fan coils. Since the new baseline also does,
> set the fan powers equal and only receive credit from reduced run hours due
> to improved envelope and such. This sounds like a nice way to guarantee
> reviewer comments.
>
> Any thoughts?
>
> Thanks,
>
>
> *Jason Kirchhoff*
> Technical Director
> Energize Analytics
> www.energizeanalytics.com
>
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-- 
M. Dennis Knight, P.E., FASHRAE
Founder & CEO
*W*hole *B*uilding *S*ystems, LLC
P.O. Box 1845
Mt. Pleasant, SC 29465
Phone: 843-437-3647
Email: dknight at wholebuildingsystems.com
Website: www.wholebuildingsystems.com
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