The typical building never stops shaking. Air conditioners, heaters and even computer fans vibrate the walls, floors and ceilings. University of California, Berkeley, researchers are working on tiny wireless devices that scavenge this continual buzz as a source of power. The devices attach to surfaces throughout a building to monitor conditions such as airflow and temperature, and contain transceivers that send data to a central computer that can adjust the climate.Better than batteries because it doesn’t run down, and more practical than wall wiring, the device’s power scavenger uses a piezoelectric material and a weight attached to a springy cantilever (photo) to convert mechanical pressure into electricity. Berkeley mechanical engineering graduate student Shad Roundy has built quarter-sized scavengers that generate 70 to 80 microwatts-enough to run a sensor and transceiver-and aims to demonstrate more-powerful devices by year-end.