Energy-efficient resource allocation can significantly reduce power consumption of network and, consequently, operating expenses. In this letter, we study the energy efficiency of long-term evolution (LTE) networks with carrier aggregation, where user equipments are able to utilize multiple component carriers simultaneously. Furthermore, an LTE-compliant optimal resource block allocation algorithm to maximize throughput while minimizing energy consumption is proposed. Single-cell multi-user simulation results show that the proposed algorithm offers significant gains in terms of cell throughput and energy consumption over the state-of-the-art solutions. © 2016 IEEE.