R-value (insulation) contain no trapped CFCs or HFCs (e.g., half-pound low density foams). On certain brands, twenty-year tests have shown no shrinkage or reduction in insulating value. This has led to controversy as how to rate the insulation of these products. Many manufacturers will rate the R-value at the time of manufacture; critics argue that a more fair assessment would be its settled value. The foam industry adopted the LTTR (Long-Term Thermal Resistance) method, which rates the R-value based on a 15-year weighted average. However, the LTTR effectively provides only an eight-year aged R-value, short in the scale of a building that
Straw-bale construction in that area using only the assembly consisting of bales, lath and plaster. The technique was used successfully for strawbale housing in rural China. Straw bale domes along the Syrio-African rift at Kibbutz Lotan have an interior geodesic frame of steel pipes. Another method to reap the benefits of straw is to incorporate straw-bale walls into a pre-existing structure. Compressed straw bales have a wide range of documented R-value. R-value is a measurement of a materials insulating quality, higher the number the more insulating. The reported R-value ranges from 17-55 (in American units) or 3-9.6 (in SI) depending on the