[BLDG-SIM] Infiltration: Standard versus Proposed Design

[Marcus Sheffer]

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                        www.sevengroup.com


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