Method for determining a consumption of electrical energy in an electrical installation comprising a group of several branches for individually distributing electricity between several loads (5a, 5b, 5c, 5d), as well as a main upstream line connecting the group of branches to an electric power supply, the method comprising the action of performing over time and recording measurements (U, I A, I B, ψ A, ψ B) taken on the main upstream line and that make it possible to establish the overall power and the energy consumed by the group of branches, the method including steps in which: a) a change is detected with regard to the electrical consumption in the installation, and b) an item of information in relation to an electric current (I 2, I 3, I 4) in one particular branch from among said branches is detected using a transducer (7, 8, 9) fitted on this particular branch, and then c) using the item of information detected using the transducer (7, 8, 9) fitted on the particular branch, an indication is established according to which said change has occurred on this particular branch, and then d) using both data from among the measurements (U, I A, ψ A) taken on the main upstream line before the change and data from among the measurements (U, I B, ψ B) taken on the main upstream line after the change, as well as said indication, a particular individual consumption of energy in said particular branch is determined, said method being characterized in that said step d) includes substeps in which: - d1) by combining said indication and a table establishing at least one correspondence between at least one category of the particular branch, said category being defined on the basis of the type of the loads in the particular branch and the way in which said particular branch is equipped, and at least one way from a set of several ways (30, 31, 32) of determining an individual consumption of energy in a branch, a way suitable for the category of the particular branch is selected from the set of ways for determining an individual consumption, - d2) using the selected way (30, 31, 32), the particular individual consumption of energy in the particular branch is determined, said individual distribution branches being connected in parallel, the electric power supply being AC, in at least one specific branch of the group of branches corresponding to a category in which the changes in power consumption occur in increments and in which a specific individual current (I 3) is flowing, one specific way from the set comprising the action of performing over time and recording measurements of an overall supply voltage of the group of several branches, measurements of the magnitude and phase offset values (I A, I B, ψ A, ψ B) of an overall supply current of the group of several branches, as well as measurements of the magnitude (I 3A, I 3B) of the specific individual current (I 3) flowing in the specific branch of the group of branches, the specific way including a step in which: e) using a measurement of the overall voltage that is substantially constant during the change, measurements of the magnitude and phase offset values (I A, I B, ψ A, ψ B) of the overall current before and after the change, as well as measurements of the magnitudes (I 3A, I 3B) of the specific individual current (I 3) before and after the change, an individual power is determined in order to calculate energy consumed in the specific branch. a) a change is detected with regard to the electrical consumption in the installation, and b) an item of information in relation to an electric current (I 2, I 3, I 4) in one particular branch from among said branches is detected using a transducer (7, 8, 9) fitted on this particular branch, and then c) using the item of information detected using the transducer (7, 8, 9) fitted on the particular branch, an indication is established according to which said change has occurred on this particular branch, and then d) using both data from among the measurements (U, I A, ψ A) taken on the main upstream line before the change and data from among the measurements (U, I B, ψ B) taken on the main upstream line after the change, as well as said indication, a particular individual consumption of energy in said particular branch is determined, - d1) by combining said indication and a table establishing at least one correspondence between at least one category of the particular branch, said category being defined on the basis of the type of the loads in the particular branch and the way in which said particular branch is equipped, and at least one way from a set of several ways (30, 31, 32) of determining an individual consumption of energy in a branch, a way suitable for the category of the particular branch is selected from the set of ways for determining an individual consumption, - d2) using the selected way (30, 31, 32), the particular individual consumption of energy in the particular branch is determined, e) using a measurement of the overall voltage that is substantially constant during the change, measurements of the magnitude and phase offset values (I A, I B, ψ A, ψ B) of the overall current before and after the change, as well as measurements of the magnitudes (I 3A, I 3B) of the specific individual current (I 3) before and after the change, an individual power is determined in order to calculate energy consumed in the specific branch.