Temperature, relative humidity, pressure and other sensor values are measured on the sensor board “Blens-Tag”. The data is sent via Bluetooth low energy to the smartphone. Using the iPhone/Android app, the data can be viewed. The data is exchanged via the Bluetooth Advertisement mode. The tags are powered by harvesting photovoltaic energy using a small solar cell. This app and the tags are developed by the Institute of Embedded Systems (InES), part of ZHAW School of Engineering.