[Bldg-sim] Appendix G Fan Power
Rosenberg, Michael I
michael.rosenberg at pnl.gov
Thu Jul 2 07:04:45 PDT 2009
The equation is meant for each HVAC system. The example in the User's
manual is probably not a very good one. If it was an 80,000 sf single
story building it would only have one baseline Packaged VAV system and
the example would be correct. If it were a multi-story building, there
would be one baseline Packaged VAV system for each floor and the example
would be incorrect.
The User's manual is correct that the power of the parallel fan-powered
terminal units in systems 6 and 8 is not included in the calculation.
The power of those fans is specifically called out in G3.1.3.14 at 0.35
W/cfm.
Mike
__________________________
Michael Rosenberg
Senior Commercial Buildings Energy Analyst
ENERGY & ENVIRONMENT DIRECTORATE
Pacific Northwest National Laboratory
2032 Todd Street
Eugene, OR 97405
(541) 844-1960
michael.rosenberg at pnl.gov
www.pnl.gov
From: Jeremy Poling [mailto:jpoling at epsteinglobal.com]
Sent: Thursday, July 02, 2009 6:41 AM
To: Ellen Franconi; Vikram Sami; Bldg-Sim; Rosenberg, Michael I
Subject: RE: [Bldg-sim] Appendix G Fan Power
This issue will start to become a problem for anyone running energy
models for LEED projects - reviewers on the new review teams are asking
to see the total fan power for the baseline broken into individual
components and reported as such in the template for Energy and
Atmosphere Credit 1. The 90.1-2004 User's Manual is also silent on the
issue; however it raises another issue. In the example (Example G-J on
page G-28) the calculations use total building supply CFM for an
80,000SF medical office building. Since the baseline is System 5 in
that example and there would be multiple zones for the baseline, it
appears that the equation should be used for the whole building only and
not individual systems. Is this how you are applying the formulas? The
user's manual notes that fan powered VAV boxes are NOT included in the
total fan power number as calculated from G3.1.2.9.
Jeremy R. Poling, LEED AP
Senior Sustainability Analyst
Strategic Services
Site Solutions | Operations | Sustainability
EPSTEIN
Architecture
Interiors
Engineering
Construction
Epstein is a firm believer in sustainability. We ask that you please
consider the environment before printing this e-mail.
________________________________
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Ellen
Franconi
Sent: Thursday, July 02, 2009 7:37 AM
To: Vikram Sami; Bldg-Sim; Michael I Rosenberg
Subject: Re: [Bldg-sim] Appendix G Fan Power
At my firm, we proportion the baseline total fan power determined as an
aggregated W/CFM based on the hp assigned to the fan motors (supply,
return, exhaust) in the design documents. Of course this assumes that
your baseline and your proposed design have a one-to-one fan
correspondence.
Ellen
Ellen Franconi, Ph.D., LEED AP
Senior Energy Analyst
Architectural Energy Corporation
2540 Frontier Avenue
Boulder, CO 80301
tel. 303-444-4149
fax 303-444-4303
efranconi at archenergy.com
http://www.archenergy.com/
>>> "Rosenberg, Michael I" <michael.rosenberg at pnl.gov> 7/1/2009 4:48 PM
>>>
You have calculated the kW/cfm correctly according to the 2004 version
of Appendix G. The allowance actually goes up a little in 2007, for your
case. As for the second part of your question, no you do not apply the
same kW/cfm to the exhaust fan. The calculated allowed fan power the
total allowed power for all fans that are part of the system, including
the exhaust fan. The cfm component is based on the supply fan cfm only.
Unfortunately, Appendix G gives no direction on how to divide the
allowed fan power up among the various fans in the system.
Mike
__________________________
Michael Rosenberg
Senior Commercial Buildings Energy Analyst
ENERGY & ENVIRONMENT DIRECTORATE
Pacific Northwest National Laboratory
2032 Todd Street
Eugene, OR 97405
(541) 844-1960
michael.rosenberg at pnl.gov
www.pnl.gov
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Vikram Sami
Sent: Wednesday, July 01, 2009 3:03 PM
To: Bldg-Sim
Subject: [Bldg-sim] Appendix G Fan Power
G3.1.2.9 Gives you a formula for calculating system fan electrical power
for supply, return, exhaust and relief. Lets sat I have a zone with a
PSZ-HP that has a supply volume of 1500 cfm. Using this formula along
with table G3.1.2.9 I get a fan horse power of 1.29 and kW of 1.17. This
equates to 0.00078 kW/cfm - which seems really high.
The second part to my question is assuming I have 500cfm of exhaust in
this zone, do I apply the same kW/cfm to the exhaust fans as well as the
return fans? It seems that the lower the fan volume the more inefficient
the Appendix G values get from these tables.
Any guidance would be much appreciated.
Vikram Sami, LEED AP
Direct Phone 404-253-1466 | Direct Fax 404-253-1366
LORD, AECK & SARGENT ARCHITECTURE
1201 Peachtree Street NE, Suite 300, Atlanta, GA 30361
Responsive Design * Technological Expertise * Exceptional Service
Please visit our new website | www.lordaecksargent.com
<file:///\\www.lordaecksargent.com\>
P Think GREEN before you print.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20090702/92461c0d/attachment-0001.htm>
More information about the Bldg-sim
mailing list