Correct use of the Kelvin temperature scale
At the General Conference on Weights and Measures in 1967–68 (13th Conférence Générale des Poids et Mesures, 1967/68 Resolution 3), it was decided that each unit of the Kelvin scale would be a kelvin, with a lower case k (Bureau International des Poids et Mesures 2006, 153). The abbreviation for a kelvin is an upper case K. Thus, the name of the temperature scale is the Kelvin (upper case K) temperature scale, but the name of the unit is the kelvin (lower case k), abbreviated to K (upper case). There should be a space between the number and the symbol; for example, “280 K” is correct, but “280K” is incorrect.
Day, T., 2009: Textbook errors in the application of the Kelvin temperature scale. J. Geography, 108, 269–270.