When utilities observe or anticipate high wholesale market prices or power system emergency conditions, they may call critical events during a specified time period (e.g., 3 pm—6 pm on a hot summer weekday), the price for electricity during these time periods is raised. Two types of rate design exist: one where the time and duration of the price increase are predetermined when events are called and another where the time and duration of the price increase may vary based on the demand of the electric grid.