Multilayer, biaxially oriented polyester films which include as a constituent of the base layer B, a crystallizable polyester with increased diethylehe glycol content and/or increased polyethylene glycol content, and/or increased isophthalic acid content, preferably polyethylene terephthalate. The outer layers of the inventive films advantageously include at least one IR-reflective pigment and one UV stabilizer. The inventive films advantageously feature adjustable mattness, diffuse scattering power for visible light, high light transmittance, IR reflectance, and good thermoformability, and are suitable for thermally protective coatings or thermally protective packaging.