## 2 Materials and Methods Background
### KNX Can Be Combined with IoT  
The KNX technology is the result of collecting the knowledge and experience gained during the 15 years of its predecessors, which were EIB (European Installation Bus), EHS (European Home System), and BatiBUS.  
ISO/IEC is a KNX system approved by the international standard ISO/IEC 14543-3 in 2006. CENELEC is a KNX system approved by the European standard EN 50090 in 2003. CEN is a KNX system approved by the European standard EN 13321-1 (referring to EN 50090) and EN1332-2 (KNXnet/IP) in 2006. SAC is a KNX system approved by Chinese standard GB/Z 20965 in 2007. ANSI/ASHRAE is a KNX system approved by the American standard ANSI/ASHRAE 135 in 2005. Consequently, KNX has become a globally recognized building and household control standard.  
The KNX system is currently being connected to a higher-level IoT system. The KNX Association has taken the first step towards standardization on the Internet side by publishing the KNX IoT web services and interface specifications, which allow gateways to be aligned with existing oBIX, OPC/UA web protocols and BACnet web services. It is important that:  
* The devices understand each other;
* People can understand what the device or service offers.  
Understanding the meaning of data (=semantics) is essential to be able to combine functionality and create new functions. The current KNX system does this by creating a project in ETS, thus relying on standardized KNX data types combining a number of products/functions. The ability to share this semantic information beyond the boundaries of the KNX ecosystem is important for IoT. Semantics allow devices and services to interact at different levels. For example, a wall switch may directly control a particular light fitting, while a mobile phone app may bring the building to \"out of home\" mode, thereby indirectly controlling the same light fitting. Semantic allows the removal of technical details and, thus, the creation of special values. An example is the command \"turn off the heating when the window is open\". Another example is \"dim the lights in the living room\", wherein the distributed system components may decide whether this should result in moving the blinds or dimming the lights. These services work to simplify interaction with building automation systems so that the end-user can control their building space without having to understand the complexities of the building automation system. It means that the defined zones of the given flat can be scheduled automatically and switched on and off according to the user's schedule set directly from the desktop of the computer, tablet, or phone.  
In addition to automation systems that use our global Internet, many services have begun to emerge that use the Cloud to support energy savings and transmit important energy, carbon, and financial information to facility staff, green teams, consumers, and financial managers. With these functions and many other options, the energy and comfort conditions can be effectively monitored and controlled to optimize them. In addition, having the almost unlimited storage capacity of the cloud, this data can be securely and redundantly stored and used throughout the building lifecycle to efficiently monitor and analyze building energy performance, maintenance performance, and cost-saving measures, all at a fraction of the cost associated with embedded systems.