Thermal conductivity in dritherm fibreglass insulation… which is better??
The lower the thermal conductivity, the better the insulation. Same for U value – lower U value, better insulation. The U value says how much power is lost per square meter of surface for each degree of temperature difference. Thermal conductivity is a property of a material and is independent of the thickness of the material. All fiberglass has the same thermal conductivity (roughly). The U value is a property of a wall, window or other surface (such as your sheets of fibreglass). For a single material, it depends on the thermal conductivity and thickness of the material. It can also be calculated for composite constructions from the thermal conductivities and thicknesses of the various materials used. For windows, it can also take account of radiative heat losses (which obviously don’t apply to fibreglass).
