Wibree achieves the low power usage by sleeping whenever its not transmitting. The main usage scenarios of wibree are such that only very little data is transmitted and that too once in a while.

Think of a remote wibree remote control for your TV. The remote usage is very low compared to the idle time. Similarly a wibree sensor network will only be transferring data in small volumes and limited cycles.

The device will be sleeping whenever its not not being used. When a wibree device is required to transmit it will wake up and it will transmit on a number of advertising channels. The receiving device will then allocate a channel for the data transmission. Once the data is transferred and acknowledged the wibree device goes back to sleep again.

Wibree saves power by using low power radio, minimising the data transfer and sleeping when not transmitting. The challenge is to achieve 1 year battery life for a normal cell sized battery.