In modern buildings air conditioning has become a task for itself. Especially in huge structures cabling is very complex and expensive since a lot of sensors are required.

At the Institute of Embedded Systems an energy self-sufficient, wireless embedded system for ventilation ducts was developed. It measures temperature, wind speed, pressure, and humidity. The sensor data is transmitted by radio. All required electrical energy is harvested directly from the air flow. The developed harvester works almost independent of the flow velocity, the output power is almost constant. From a cut-in flow velocity of 1.25 m/s, there is enough electrical energy available to operate a servomotor in addition to the embedded system.

The developed prototype is tested in a wind tunnel. Experimental results show the potential for applications. The harvested energy is sufficient for measure, process and send data in regular intervals. Even at low air flow velocities enough energy is available to drive a motor. Thus, a ventilation flap can be adjusted to regulate air conditioning.

As the system is fully energy autarkic no wiring is required. This minimizes installation and maintenance effort considerably. Moreover, the system is designed for long life service and is resistant to contamination. Nevertheless, applications in various fluids would be possible.