Dissemination of the redefined kelvin

Short Name: DireK-T, Project Number: 22IEM02
Image showing An old style industrial thermometer
An old style industrial thermometer

Implementing primary thermometry in European industry

Temperature is one of the most measured parameters in industry. Primary thermometry measures temperature thermodynamically relative to a primary constant, whereas secondary thermometry measures temperature relative to defined points on a scale, for example the freezing point of water.

In 2019, the Kelvin was redefined relative to the Boltzmann’s constant, making it possible to measure exact thermodynamic temperature. The previous EMPIR project Real-K  worked with primary thermometry techniques to measure temperatures higher than 1235 K and lower than 5 K.

However, further dissemination of thermodynamic temperature is needed to ensure that the measurements are reliable and to determine the degree of equivalence between primary and secondary thermometry approaches.


This project will develop guidelines for thermodynamic temperature dissemination over a range of 4 K to 300 K to ensure consistency between European National Metrology Institutes. As part of this goal, the traceability of thermodynamic temperature from 25 K to 300 K, as well as the dissemination of thermodynamic temperature from 4 K to 25 K with defined scale level uncertainties will be demonstrated. Additionally, the metrological basis for disseminating and realising thermodynamic temperature for the temperature range of 300 K to 700 K will be designed.

These outcomes will be shared with the wider scientific community by publishing at least 15 research papers and presenting at 20 relevant conferences. Moreover, a summer school targeted at academics and metrologists will be held.


Overall, these changes will help implement the wide-spread use of thermodynamic temperature measurements in European industries.


Other Participants
Industrial Technology Research Institute (Taiwan, Province of China)
National Institute of Metrology - NIM (China)
Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences (China)