ISO 8990:1994

Lays down the principles for the design of the apparatus and minimum requirement that shall be met for determination of the laboratory steady-state thermal transmission properties of building components and similar components for industrial use. Does not specify a particular design. Describes also the apparatus, measurement technique and necessary data reporting. Primarily intended for laboratory measurements of large, inhomogeneous specimens. Does not provide for measurements where there is mass transfer through the specimen during the test.