A method of metering the energy applied to a downstream process employing a cryogenic fluid, comprising the following steps: a) separating the liquid and gas phases of the cryogenic fluid before the cryogenic fluid reaches the downstream user process. b) Measuring the mass flow rate of the gas phase. c) Calculating the energy flow rate associated with this gas flow rate by taking into consideration the variation in enthalpy of the gas between its vaporization temperature and the gas temperature recorded at the outlet of said downstream process in real time. d) Measuring the mass flow rate of the liquid phase, e) Calculating the energy flow rate associated with this liquid flow rate taking into consideration the temperature of the liquid and the vaporization energy of the liquid cryogen at this temperature, and taking into consideration in the case of the gas resulting from the vaporization of this liquid, the variation in enthalpy of this gas between its vaporization temperature and the temperature of the gas at the outlet of said downstream process in real time. f) (Re)combining the two, liquid and gas, phases of the fluid in order to allow it as this combination to be fed to said downstream user process.