<p>A method, system and device for synchronizing a time period over which energy measurements are accumulated for an energy monitoring system including a plurality of energy monitoring devices is described. The method comprises transmitting a first radio frequency packet from a time reference device via at least a first and a second of the plurality of energy monitoring devices to a third of the plurality of energy monitoring devices. The method further comprises adjusting a time register within the third energy monitoring device based on the reception of the packet. The method further comprises accumulating a measure of energy consumption by the third energy monitoring device of a load coupled with the third energy monitoring device. The method further comprises transmitting the measure of energy consumption from the third energy monitoring device via at least a fourth and a fifth of the plurality of energy monitoring devices to a data aggregation device. The method further comprises identifying by the data aggregation device an aggregate measure of energy consumption consumed by the load over the time period.</p>