Researchers at Oak Ridge National Laboratory have carried out extensive testing and modeling of Agriboard straw-core structural insulated panels. This testing was referred to in the article “Agriboard’s Inflated R-Value Claims” in the January 1998 issue of EBN, though the results had not yet been released at that time. While the steady-state R-value testing indeed showed R-values significantly lower than Agriboard had claimed (R-16.5 vs. R-28), Agriboard—to their credit—also funded sophisticated dynamic testing and modeling of their panels to arrive at mass-enhanced R-values under various climates. These results are very interesting. Following the steady-state R-value testing, researchers used a guarded hot box to measure conductivity of Agriboard panels under dynamic conditions. One side of an 8’ x 8’ wall assembly was kept at a constant 100°F, while the other side was held at 60°F for a period of time, then gradually dropped to 30°F. The results from this testing were used to calibrate a computer model that was then used to simulate energy performance of a simple one-story house built of Agriboard panels for comparison to ten different frame wall configurations ranging from R-2.3 to R-37. By simulating the performance of these houses in six different climates, investigators were able to determine the mass-enhanced R-value of the Agriboard panels under these conditions—in other words, how well insulated a conventional (low-mass) frame wall would have to be in those climates to achieve the same energy performance as the Agriboard house—see table.
