July 2010: I can't remember if I gave all the details about our exterior construction (Structural Insulated Panels - SIPS) and since someone asked recently, here is the info:
Apparently, studies have shown that determined R-Values have little correlation with how an insulating material actually performs in a non-SIP home. When taking into account factors such as cavity voids, wiring without compression, and paper facer stapled to studs, the actual R-Value decreases significantly.
SIPS homes avoid these familiar problems by distributing insulation uniformly among the entirety of the panels. Without these negative effects, actual R-Value of insulation within a SIPS panel can actually exceed its determined R-Value
Our exterior walls are 4 1/2" SIPS and the roof is 10 1/4". Here is a table from our SIPS manufacturer, Fischer SIPS:
R-Value Comparison to fiberglass:
| Panel Thickness: | Actual R-Value | Performance Value |
| 4 ½” | R-17 | R-25 |
| 6 ½” | R-25 | R-38 |
| 8 ¼” | R-33 | R-50 |
| 10 ¼” | R-41 | R-62 |
| 12¼” | R-48 | R-72 |
Soon, we will post our actual electric bills showing the kw/h per square foot as well.
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