## 3 Methodology: Requirements Analysis, Selection of Buildings, and Technologies
### Goals, Requirements and Implementation Measures  
Within the scope of LLEC, we intend to develop, test, and evaluate new automation variants, allowing for reduced energy consumption, an increased use of renewable energy sources, and the integration of energy storage in the building sector.  
In the scope of this paper, we specifically focus on hardware-related instrumentation processes that we apply at the campus of FZ Julich to enable monitoring and control at the room level. Moreover we give a short overview of the possibilities of integrating interaction points with automation elements on the building level for scientific purposes. To draw reliable conclusions and to allow for more elaborate comparisons, several buildings shall be equipped, operated, and monitored.  
With regard to controlling and monitoring at the room level, it becomes necessary to fully equip rooms with sensors and actuators to measure their (thermal) state and to influence it, respectively. This especially holds true for older buildings, where currently there are generally no sensors or control networks in place. In the small number of rooms where sensors or actuators exist, room-level automation and control was only applied in a basic sense--local, isolated, and mostly unsophisticated controllers that handled aspects of room automation such as lighting or heating--which did not allow for utilization in an overarching MPC approach.  
Likewise, at the building level, automation is present at least to some extent. For example, the metering of energy flows into the building (e.g., electricity or district heating) plays a major role for facility managers operating the buildings on campus, and a control of the heat supply temperature is implemented for every building. Although the present BACS installation in most buildings would, in theory, allow for control concepts superior to simple rule-based control, no (cloud-based) access points for data collection were available prior to the start of this project, so it was not possible to apply advanced cloud control concepts using the available infrastructure.  
A holistic approach to building monitoring and control consequently requires at least temporary access to these infrastructures. Therefore, it is necessary to select appropriate devices and technologies depending on the buildings' individual prerequisites.  
In Figure 1, the connection points at the different levels of existing buildings are shown in the context of a sample district energy system. The connection to the ICT infrastructure for scientific purposes is indicated for different elements inside the total district energy system. Connections between the ICT infrastructure and metering at the building level, as well as automation at the building level and at the room level, are highlighted, as they are in focus in this work.  
In the cases where scientific operation modes (e.g., an innovative control strategy) are to operate existing infrastructure, a safe \"standard\" operation mode still needs to be available. Moreover, a sophisticated \"kill switch\" needs to be implemented as a \"safety hatch\" for linking to existing automation structures (as seen, e.g., in [24]), including automation hardware and software. Such a kill switch is meant to enable the basic operator of the infrastructure to deny or allow scientific interaction with the buildings' technical automation equipment. If necessary, automated checks might also be enabled, which can deny write access to existing building automation in cases of malfunction or unexpected behavior.