[BLDG-SIM] Infiltration: Standard versus Proposed Design

[Brian Thornton]

Is it the sense of the group that infiltration can be predicted well enough
in commercial buildings to take credit for energy savings in this area?  I
considered this issue a few years ago, and the literature seemed to indicate
that prediction was very poor, and that field work indicated that
infiltration would vary substantially, in the same building under similar
outside temperatures due to small differences such as a few windows or doors
opended differently, and that it was in most cases unclear what the
differences were due to.
 
Brian Thornton
Glumac, bthornton at glumac.com

-----Original Message-----
From: Marcus Sheffer [mailto:sheffer at paonline.com]
Sent: Wednesday, May 19, 2004 9:00 AM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Infiltration: Standard versus Proposed Design


Right now infiltration reduction is not an eligible item for energy cost
reduction for LEED.  Infiltration rates must be the same in the proposed and
budget buildings.

My understanding is that the Energy & Atmosphere Technical Advisory Group
(EA TAG) of the USGBC is considering this issue with an eye toward
developing a modeling protocol.

I am aware of at least two projects that have applied for savings in this
area which have been put on hold (the LEED points were denied pending
further input from the EA TAG).  


As At 10:33 AM 05/19/2004, you wrote:


Can infiltration be considered in comparing standard versus proposed design
models using the ECB method and for LEED credits under "Optimize Energy
Performance"?  Typically we use the same criteria in both models, but this
is a particular case of a proposed double-wall building.  "10CFR435 Table
402.2.1. - Air Leakage for Fenestration & Doors Maximum Allowable
Infiltration Rate" provides standard model information for federal
buildings.  For example, the infiltration rate is 0.15 cfm/ft2 for fixed
aluminum windows.  Can this be used for LEED standard design and can a lower
rate be used for double wall buildings?
 
The CFR table does not account for Heating & Cooling Degree Days as with
Table-B Building Envelope Requirements of STD90.  In my opinion, the peak
design infiltration rate should be varied from maximum in winter to minimum
in summer (typically zero for pressurized buildings) using a schedule.  The
maximum, of say 0.15 cfm/ft2, would apply to a cold climate such as Chicago
and it should be scaled down for warmer climates.  Since DOE2 does not allow
infiltration rates on the basis of cfm/ft2 of wall or window area or cfm per
lineal foot of window perimeter, we create a typical perimeter space and
convert the window based infiltration rate to cfm/ft2 of space area or space
air changes. We then look at the results in "REPORT- LS-C BUILDING PEAK LOAD
COMPONENTS" of the DOE2 output to see if the infiltration load looks
reasonable (relative to the other loads) for the location and type of
building and make adjustments by trial and error.  Judgment and experience
is considered more reliable than theoretical mathematical models.  The BEPS
and BEPU reports in DOE2 should separate out the infiltration loads from the
heating & cooling loads.  Any comments?
 
Thanks for the comments and suggestions to using different utilities in
standard versus proposed design.  They were very helpful in making some
decisions here.  Most of the responses seem to go directly to the person
asking the question.
 
Varkie Thomas
Skidmore, Owings & Merrill LLP
 
 
 






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Marcus B. Sheffer                          energy & environmental consulting
Energy Opportunities, Inc              717-292-2636
1200 E Camping Area Road            Fax: 717-292-0585     
Wellsville, PA USA 17365-9783        sheffer at sevengroup.com
a 7group company                         <http://www.sevengroup.com/>
www.sevengroup.com




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