Parametric Problem - Envelope Study

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I am attempting to establish a few alternatives compared to an ASHRAE 90.1 Wall construction.  This much seems pretty straightforward with the only change between alternatives being a different construction applied to the exterior above grade walls. All alternatives are modeled as delayed and with layered materials. The wall from outside to inside is stucco(finish) R0.08 + Cont. Insulation R-VARIES + Ext sheathing R0.56 + Framing/Insulation R-VARIES* + Int. Sheating R0.56 (air films do not change, infiltration does not change, etc.)

*framing 16" Mtl OC taken into account

<<< I should mention the building is very much internal load dominant as an education building with a lot of laboratory space >>>

The problem as illustrated below is pretty clear in that while the conduction loads in LS-C vary slightly (all under 8%) between all runs, there seems to be a problem with ALT1.  THe calc U-Value for the Baseline is 0.64. U-Value for ALT1 is 0.61.  Thoughts?  Is the answer in the difference between the entered "R value" for Framing Insulation vs the specified material properties of the exterior insulation?


BASELINE - 90.1 -                              R6* + 7.5 ci                  na

ALT1 - only ext insulation                   R0.9   + 12 ci              -8% savings (% energy under EUI - kBtu/sf/yr) 

ALT2 - improved ext insulation           R6* + 12 ci                 +1% savings

ALT3 - improved cavity insulation       R7.1* + 7.5 ci             +1% savings

ALT4 - all insulation improved             R7.1* + 12 ci             +2% savings

I also could use some guidance as to why the parametric run reports are telling a much different story than the comparison reports.  ie. increased energy consumption for annual utilities under comparison reports vs whats listed above.

As a novice, I greatly appreciate any help.

Nicholas Fonner
Energy Modeling Group
Henneman Engineering, Inc. | energy. focused.
1605 South State Street, Champaign, IL 61820
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