For a cluster of cellular communication sites, the power consumption and data load of each site is measured over multiple time periods to determine an energy factor indicating the degree by which the power consumption of each site increases with increasing data load. The energy factors are then analyzed to determine coverage area sizes for the communications sites that will serve a given area while taking advantage of more efficient site to reduce overall power consumption of the cluster of sites. Transmission power levels are then adjusted at the sites to achieve these coverage area sizes.