There are mainly three types of heat insulation panels: Polyurethane (PU), extruded polystyrene (XPS), and expanded polypropylene (EPP) – and each has different performance attributes. They are all foam core panels.
PU foam panel
PU foam is a new closed-cell structure synthetic material with thermal insulation and waterproof functions. Its thermal conductivity is only 0.022-0.033W/(m*Κ), which is equivalent to half of the extruded board and has the lowest thermal conductivity among all thermal insulation materials.
XPS foam panel
XPS is a recyclable material mostly used in walls and lower grade applications. XPS foam panels provide about R-5 per inch of thickness and fall between ISO and EPS in cost. However, XPS absorbs more moisture than other insulation panels over time.
EPP foam panel
EPP foam is a closed-cell bead foam that provides a unique range of properties, including outstanding energy absorption, multiple impact resistance, thermal insulation, buoyancy, and water & chemical resistance.
About Thermal Bridging
A thermal bridge occurs when penetration of the insulating layer takes place along your walls, allowing heat and cold to pass through undisturbed. With fiberglass and wood framing, each wood stud represents a thermal short circuit where moisture-filled, heat-transferring air can pass through the barrier. The stud area accounts for 15% to 25% of the wall surface and significantly reduces the R-value of the fiberglass.