Smart Building Integration (SBI) relies on using wireless sensors. These sensors must be powered. Cabling is too expensive and cumbersome, batteries have unacceptable maintenance and environmental issues and energy harvesting is not always possible. SBI will become feasible by employing rechargeable batteries that are remotely being recharged by means of radio waves while being functionally active within the sensor. Within the legal power restrictions and obeying the health exposure limit recommendations, the employment of a dedicated RF source has demonstrated the charging of a 3V battery indoors up to a distance of 18m.