KNX is a worldwide open standard for home and building automation, which originated from a classical fieldbus protocol. While the needs for interacting with the upcoming Internet of Things (IoT) were already partially addressed by the recent KNX Web Services application note, KNX IP networking still supports IPv4 only. This paper proposes the usage of IPv6 networking as native KNX medium. The most obvious approach of mapping the existing KNXnet/IP mechanisms from IPv4 to IPv6 is neglected, and more elaborate solutions to existing issues in KNXnet/IP networking are discussed. The main objective is a better utilization of IPv6 features for a possible KNX IPv6 architecture, resulting in increased performance and compatibility to standard Information and Communication Technology (ICT) networking. Therefore, several core design issues are raised and discussed in the course of this work. A transparent mapping approach between KNX and IPv6 addresses is proposed to facilitate the huge IPv6 address space. Further, the introduction of multi-homed Internet connectivity and node mobility by the usage of the Locator/ID Separator Protocol (LISP) is examined. Security considerations are addressed by comparing the upcoming KNX IP Secure standard to IPSec network layer security. Finally, the feasibility of the proposed approaches is shown with the help of a proof-of-concept implementation deployed in a small scale IPv6 testbed network.