In electric energy distribution, emergency power supply is of primary importance. If a decrease in the available electrical power is shown, not all the devices can continue to be fed. Emergency power systems, in general, are designed to supply a limited part of the existing devices. Moreover, backup systems cannot \"follow\" the technological evolution of the plant. Conventional control systems adopt as unique action the switching off of standard loads. The aim of this paper is to provide a strategy for the load management through the selection of loads in the local smart grid as a function of the total available power. A method of control through the application of the 0-1 Knapsack Problem is proposed. The solution relies on three different algorithms and implementations: a greedy and heuristic, the Tabu Search and the dynamic programming. In order to evaluate the performances of the method, a case study is discussed.