This European Standard specifies a method, based on EN ISO 8990 and EN ISO 12567-1, to measure the thermal transmittance of frame and sash components of windows and doors, including mullions and transoms. The thermal bridging effect of window or door components (handles, hinges, closing devices, etc.) is included. The test procedure is designed to take into account the whole developed area of the frame or sash surface, but excludes the influence of the thermal bridge introduced through the spacer in sealed glazing units. Edge effects occurring outside of the perimeter of the specimen are excluded. Furthermore, energy transfer due to solar radiation is not taken into account, and air leakage is excluded. The measurements are performed under defined conditions to facilitate the comparison of measured values. Information on the design of the calibration transfer standard is given in EN ISO 12567-1.