## 3 Methodology: Requirements Analysis, Selection of Buildings, and Technologies
### Deriving Technologies and Instrumentation Variants
#### 3.3.3 Selected Variants
In this case, the EnOcean valve actuator will be integrated into the KNX backbone via EnOcean/KNX gateways, so as to allow users to control the heating via the HMI in the basic operation mode also. Figure 4 shows a conceptual equipment variant for such a solution. Table 5 shows some of the KNX devices also used within the LLEC project. By also connecting the IPC to the KNX bus, the KNX devices can also be used to widen the data available for scientific purposes as well as to give additional actuators to be possibly included. To make actuators based on KNX available for scientific purposes at any point, a \"kill-switch\" element is to be introduced inside the KNX program. This switch element then allows one to decide whether a control command sent by the IPC or by a standard element in the KNX program becomes active. In addition to broadening the number of available sensors and actuators, another advantage of KNX installation is the availability of more elaborated HMIs directly on the field level. An example where such a technique is already installed successfully is the JSL. Whenever possible, wired KNX sensors and actuators were installed, primarily based on guidelines and regulations set by the infrastructure manager. This includes the following devices:  
* **presence sensors** in offices, labs and meeting rooms;
* **person counters** in labs and meeting rooms;
* **air multisensors** in offices, labs and meeting rooms;
* **electric meters** in offices, labs and meeting rooms;
* **human-machine interfaces** (HMI) in every room;
* **lighting** actuators;
* external **blinds actuators**, if present;
* floor heating **valve actuators** on the ground floor. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Device Type 1** & **Manufacture** & **Model Name** & **Purpose** \\ \hline IoT Gateway & Beckhoff & CX5130 2 & * low-level automation and control * collect data from (multiple) bus(es) * access point to cloud \\ \hline EnOcean Transceiver & Beckhoff & KL6583 & * receive EnOcean telegrams * send EnOcean telegrams \\ \hline Air Multisensor & Pressac & 60.CO2 SLR TMP HUM.868 & * measure air CO2 * measure air relative humidity \\ \hline Window Handle & Thermokon & SRG02 & * measure window state (open/closed/tilted) \\ \hline Contact Sensor & Eltako & FTKB & * measure window/door state (open/closed) \\ \hline Valve Actuator & Micropelt & MVA005 & * control radiator valve position * implement local backup controller \\ \hline \hline \end{tabular}  
* device type based on Figure 3; 2 including necessary I/O and bus terminals.  
\end{table} 
Table 4: Overview of selected physical EnOcean-based devices, including manufacturer, model, and purpose. Additionally, wireless sensors were used where necessary. Due to the market availability of a variety of devices that are based on the EnOcean protocol [71], devices using the EnOcean technology were used. The set of EnOcean sensors and actuators installed in the JSL comprises the following items:  
* **contact sensors** for door and window state measurement;
* **radiator valve actuators** in offices, labs, meeting rooms, and other common areas;
* a limited set of **air multisensors** in offices, labs, and meeting rooms to compare KNX/EnOcean sensor characteristics. In the JSL, all wireless EnOcean devices were integrated in the KNX system via dedicated, bidirectional EnOcean/KNX gateways. The gateway installation positions were chosen based on radio range tests, minimizing the overall number of gateways used. The wired KNX backbone is connected to one IoT gateway, which can send and receive telegrams on the bus. While a conventional building automation layer is established via the KNX program, the gateway also allows for advanced building control, e.g., via cloud-based algorithms. To assure safe and comfortable building operation, even in cloud-based operation mode, a \"kill switch\" is implemented in the IoT gateway.