# 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?

Example.

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
V 217.359.1514 | F 217.359.9354 | C
www.henneman.com | nfonner@henneman.com

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