This report discusses one part of a project consisting of three parts. The goal of the project is to design a battery less sensor powered by RF energy fields present in an office environment. The sensor is able to measure temperature and is able to communicate wirelessly using a low power communication protocol. In this project the use case of a building is explored. In this thesis the possibilities of low power sensing, processing and communicating are investigated. Different options for sensing, processing and communication chips are discussed. Measurements in terms of communication range and power consumption are performed on the system. A TMP-102 temperature sensor, an ATtiny84A microcontroller and an SX1272 LoRa module are chosen. Roughly 4 mJ is needed to perform a measurement and transmit it. Further research is needed to reduce the energy consumption even further.