UNE-EN ISO 22007-6:2015

The thermal conductivity of materials that are poor conductors of heat is usually determined by measuring the larger temperature gradients in the sample produced by a steady flow of heat in one-dimensional geometry. In order to reduce the errors of radiation and convection, it often requires large, precisely shaped samples and extreme care to be used successfully.
This international standard specifies a modulated temperature method realizing the measurement of thermal conductivity. An input of temperature deviation is less than 1 K, and a double lock-in method is applied to amplify the small temperature modulation.
The ISO22007-3 specifies one of the modulated temperature methods where the phase shift is measured in the thermally thick condition kd >>1 (k=(wð/2að)1/2, wð: angular frequency of temperature wave, að thermal diffusivity, d: thickness of the specimen). In this condition, the backing material does not affect on the phase shift results on the sensor, on which temperature wave decays exponentially.
On the other hand, if kd