Techniques and mechanisms for determining constraints to be imposed on resource utilization by customers of an electric utility. In an embodiment, flexibility metrics are determined each for a different respective customer, the flexibility metrics each indicating a respective difference between a metric of resource utilization, and a respective constraint which is imposed on that resource utilization. The customers are ranked, relative to one another, based on the flexibility metrics, where the ranking is used as a basis for selecting one or more customers to accommodate a change to a power delivery service of the electric utility. In another embodiment, one or more updated utilization constraints are imposed each by a respective customer of one or more selected customers.