An optimal power flow framework is proposed as a tool to evaluate demand-side management (DSM) activities. The formulation provides an analytical framework to estimate the effects of potential efficiency improvements due to DSM on energy price. It may account for network constraints as well as several generator dynamic restrictions, such as generation ramp-rate limits and fuel constraints. Price-responsive loads are modelled through benefit functions, in which interactions between dispatch intervals are considered. It is possible to take into account other constraints on consumer processes that also behave as dynamic restrictions. The problem is formulated as a dispatch of generation and demand over a time horizon of several dispatch intervals, but is solved as a single optimisation problem. The IEEE 14-bus test system is used to illustrate typical results that can be obtained through the proposed methodology.