The energy efficiency of a wireless client is an important issue for wireless network environments. A common strategy for energy saving in wireless network devices is to remain in sleep mode when data are not being transmitted or received. However, when multiple TCP flows are established from a wireless client, determination and control of sleep timings are difficult. In addition, frequent state transitions between active and sleep modes consume energy, resulting in a reduction in energy efficiency. In this paper, we propose an energy-efficient method formultiple TCP flows in wireless LAN (WLAN) environments. The proposed method is termed SCTP tunneling, and aggregates multiple TCP flows into a single SCTP association between a wireless client and access point to control packet transmission and reception timings. Furthermore, SCTP tunneling lengthens sleep time by transmitting and receiving multiple packets in a bursty fashion. In this study, we construct a mathematical model of the energy consumed by SCTP tunneling to assess its energy efficiency. Through numerical examples, we show that the proposed method can reduce energy consumption by up to 69%.