Specifies the procedure to be followed to obtain, from the measured values of thermal conductivity determined in accordance with DIN 52612 Part 1, hereinafter designed lambda g, a value lambda z that serves as a basis for establishing a calculated value of the thermal conductivity (value to be used when verifying by calculation) for building applications, or as a basis for determining whether the material tested complies with the calculated value stipulated by the building inspectorate.