## 3 Methodology: Requirements Analysis, Selection of Buildings, and Technologies
### Deriving Technologies and Instrumentation Variants
#### 3.3.3 Selected Variants
On the one hand, metering data, including heating, cooling, electricity consumption, and tap water use, are acquired by the on-campus infrastructure management. These data are accessed for research purposes through a TCP/IP-based interface between the existing campus infrastructure and our ICT infrastructure. The implementation of a first version of this coupling is described in [76]. Technical details for the interface are not within the scope of this paper, but will be presented in a separate paper in preparation. On the other hand, first steps towards the integration of additional M-Bus [77] meters for research purposes have been taken. These meters can be integrated with the previously described IoT gateways in the selected buildings. Combination of Protocols Used in the Climate-Neutral Administrative Building (CAB)  
In the CAB, which is currently under construction, it is planned to integrate all listed protocols of BACnet, KNX, EnOcean, and M-Bus. BACnet will be used for the operation of the actuators of TABS, heating and cooling ceilings, VAV systems, AHU, heat pumps, and buffer storage. KNX is used for the room-individual actuators of the underfloor convector,  
Figure 5: Layout of low-temperature district heating network  
shading blinds, and illumination (also coupled to DALI [78]). Sensing in KNX is realized for room temperature, occupancy, and illuminance. Users can specify their room-specific comfort preferences for shading, illumination, and room temperature control via state-of-the-art HMIs. EnOcean is employed for further room sensor equipment through window and door sensors (for evaluation of the ventilation concept) and multisensors (temperature, CO\({}_{2}\), humidity). For metering heating, cooling, and electrical energy flows, M-Bus meters are included. In the CAB, distributed and hierarchical MPC concepts will be implemented; these are currently developed and evaluated based on simulative test beds [79]. Controller and simulation models are created based on the open-source Modelica simulation library AixLib [80]. The base for the application of innovative control concepts can be implemented as an additional control layer added to the standard building automation control. In order to be capable of applying both innovative and standard control strategies, \"kill-switch\" elements are introduced. These are accessible logic elements implemented in the building automation to switch between different control modes. It is favorable to implement the \"kill switch\" at a higher spatial resolution to be able to evaluate control strategies on a smaller scale that is exposed to a small number of disturbances and interactions, simplifying fault detection and system analysis. For example, for a multi-floor building, the \"kill switches\" can be configured to be spatially resolved according to individual floors, or further separated into thermal zones. A higher spatial resolution of the \"kill switch\" simplifies the comparison of an innovative control strategy to a reference control, which can be applied at the same time to another area of the building that is exposed to the same weather disturbances and operation conditions. Apart from this, the \"kill switch\" could be also resolved according to groups of actuators (e.g., heating, ventilation, shading) to focus on a subgroup of components, which facilitates a comparative analysis. For central components such as an AHU or a heat pump, it is recommendable to implement individual \"kill switches\". For the evaluation of innovative control strategies, it is further interesting to enable control at different control levels. A ventilation system, for example, can be controlled by specifying a set-point for the CO\({}_{2}\) concentration (_reference variable_) of the ventilated area, or by prescribing a volume flow rate (_manipulated variable_).