R-value (insulation) as ASHRAE 90.1 and the IECC prescribe U-values. However, R-value is widely used in practice to describe the thermal resistance of insulation products, layers, and most other parts of the building enclosure (walls, floors, roofs). Other areas of the world more commonly use U-value/U-factor for elements of the entire building enclosure including windows, doors, walls, roof, and ground slabs. The SI (metric) unit of R-value is whereas the I-P (inch-pound) unit is For R-values there is no difference between US customary units and imperial units, so the same I-P unit is used in both. Some sources use ″RSI″ when referring
Building insulation materials one side to another due to the reflective surface (or low emittance). There are a lot of definitions about “Thermal/Heat Insulation” and the common misinterpretation of “Thermal/Heat Insulation” = “Bulk/Mass/Batt Insulation” which is actually uses to resist Conduction Heat Transfer with certain "R-Value". As such Materials reflecting Radiant Heat with negligible “R-Value” should also be classified as “Thermal/ Heat Insulation”. Thus Reflective Insulation = Radiant Barrier Certain forms of insulation used in the past are now no longer used because of recognized health risks. Urea-formaldehyde insulation releases poisonous formaldehyde gas, causing indoor air quality problems. The chemical bond between the