This standard 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. It does not, however, specify a particular design since requirements vary, particularly in terms of size, and also to a lesser extent in terms of operating conditions.
DS/EN ISO 8990:1997 history
1997DS/EN ISO 8990:1997 Thermal insulation - Determination of steady-state thermal transmission properties - Calibrated and guarded hot box