It is estimated that the Information and Communication Technology (ICT) industry is responsible for approximately 2 to 4 percent of the total carbon produced by human activities, which is equivalent to about 25 percent of total vehicle emissions and almost equal to the total carbon emissions of aircraft in the world. In the meantime, sixth generation (6G) communications play a major role in current and future ICT by providing high data rates for users and industries and have high energy consumption. On the other hand, due to high losses in 6G operating frequencies, the communication range is short and for maximum network coverage, many base stations (BS) are required, which both have high energy consumption and cause environmental pollution. To reduce energy consumption in wireless systems, especially 6G, reflective smart surfaces (RIS) have recently been proposed, which enable communication in blind spots with minimal energy consumption. This feature makes them a suitable option for improving energy efficiency in wireless networks. In this paper, the energy efficiency of 6G telecommunication systems at two mid-band frequencies of 7.8 and 15 GHz is investigated and calculated using RIS. The effect of path loss on signals is considered with real data resulting from the 3rd Generation Partnership Project (3GPP) standard, and the effect of the number of RIS elements, transmission rate, operating frequency, and other parameters in different scenarios is investigated. It is shown that the use of RIS can provide higher energy efficiency, which also increases with increasing frequency.