Metering is necessary to determine how much load reduction is achieved. Fifteen minute metering was cited as adequate. However, aggregated load curtailment programs have been put together in three to six months. Periodic testing is needed to ensure that curtailment will be available if needed. For example, Planergy tests its programs annually.
Some processes are sensitive to ambient temperature or other seasonal factors.
Things that you might be able to do in the summer you might not be able to do in the winter or vice versa. Lost production cannot be recaptured under full capacity conditions. Lead time matters. For the most part, we are not talking about using load reduction for operational reserves for system stability purposes. These situations require a very rapid response.