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
Air Quality Egg different versions; depending on what customers choose, the egg can measure Particulates (PM10, PM2.5 and PM1.0), CO2, NO2, SO2, ozone, carbon monoxide and/or Volatile Organic Compounds. The Particulate version detects particles as small as 0.3µm (microns), using two Plantower PMS5003 sensors. The PM2.5 measurements of the Air Quality Egg version 2 had an R² correlation factor of 0.79 to 0.85 with a professional reference sensor, in a field test run by the Sout Coast Air Quality Management District (an R² approaching the value of 1 reflects a near perfect correlation, whereas a value of 0 indicates a complete lack of