A scale of temperature proposed by Lord Kelvin (William Thomson), which does not include negative values. The unit of the scale is the kelvin (K), 1 K = 1  °C, 0 K = −273.16  °C. The base of the scale, absolute zero, is the lowest possible temperature for all substances at which no molecule possesses any heat energy. The triple point of water is given as 273.16 K.