 By measuring the actual energy loss in two identical homes – one built with SIPs (house on left, above) and one built with stud-and-batt walls (house on right) – Dr. Tony Shaw came to a number of revealing conclusions:
Conclusions:
- The 2x6 wall house had 68% more air leakage than the SIP house.
- The R-19 fiberglass insulation performed at an equivalent R-4 level
when the outdoor temperature was -10.5ºC (13.1ºF).
- The SIP wall house with R-17 EPS insulation maintained its true
R-value throughout the duration of the 1 year study.
- The R-17 EPS SIP wall house used 33% less energy than the R-19
fiberglass wall house.
 The reason why the fiberglass R-19 decreased to an R-4 is because air infiltration is occurring in the wall cavities through the OPEN CELLS. The fiberglass is in a non-sealed environment or non-steady state environment – unlike when it was tested and rated in the laboratory.
The reason why the SIP EPS insulation averaged an R-17 R-value throughout the duration of the study is because the EPS insulation was installed in a steady state environment, just as when it was tested. The CLOSED CELLS of the EPS insulation do not allow air infiltration to occur.
Pages
Part 1 - R-Values in Today's Building Codes
Part 2 - Designing R-Values: In the Lab
Part 3 - Air Infiltration
Part 4 - "Real Time" R-Values
Part 5 - Oak Ridge National Laboratory Study
Part 6 - Brock University Study
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