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
Construction industry of Japan non-housing structures (see table 19, Appendix). After employment peaking at 9.9% in 2003, the construction industry in Japan has entered a long, steady decline with workers share dropping to 7.0% by 2017. This decline is attributed to gradually slumping demand for the new houses. Japanese construction worker productivity have surpassed US productivity in 2006, but as in 2017, productivity of 0.24 houses/worker*year is still below peak value of 0.32 houses/worker*year in 1992. This downward trend (although less pronounced than in the US) is mostly attributed to the increasing median age of the construction workers. The productivity on concrete-making industry remains