Capacity forecasting

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for generating a load adjustment simulation and a capacity forecast. In one aspect, a method comprises: generating, using a simulation system, a load adjustment simulation that characterizes predicted energy consumption by a population of energy consuming devices based on performance of a current load adjustment event; generating, using the simulation system, a baseline load simulation that characterizes predicted energy consumption by the population of energy consuming devices based on non-performance of the current load adjustment event; determining, using the baseline load simulation, a load adjustment simulation error that is an estimate of an error between: (i) the load adjustment simulation, and (ii) actual energy consumption by the population of energy consuming devices based on performance of the current load adjustment event; and updating the load adjustment simulation using the load adjustment simulation error.