Control Strategy
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Cognitive Optimization
Optimizing building automation systems includes a large potential in terms of energy efficiency and thermal comfort. Once parameterized, building automation systems are often let well alone as handed over after construction’s completion due to the lack of skilled professionals, time or money. Two approaches, cognitive based and algorithm based, are carried out to optimize the building automation at the new E.ON ERC Main Building. The process of increasing the understanding of the energy concept’s characteristics, developing new control strategies, their evaluation via simulations, and, given superiority, applying to the building is termed cognitive optimization.
Control Optimization System
The building automation uses BACnet over IP as communication protocol at the management layer and BACnet MS/TP at the automation layer. An external SQL database is connected via the common OPC interface. Changes in specific set point or control parameter vectors within the SQL database are observed and communicated to the building automation. The SQL database serves as an interoperable flexible interface and integration point of additional data, like weather data and forecasts, demand side management signals etc. External optimization routines can gather data from and write results into the database. A promotional display and a web service publish energy and thermal comfort relevant data.
PEBBLE
The goal of PEBBLE is to maximize the net energy produced (NEP) by buildings through intelligently matching their energy consumption to energy generation. The challenge lies in the ability of the building’s control system to make (almost) real-time decisions under the constraints of unpredictable user-behavior, occupancy scheduling or weather conditions. For the E.ON ERC main building, PEBBLE will be implemented in the northern area of the concrete core activation, where it will control the temperature set points of the façade ventilation units and the overall power of the water circuit. An initial controller will be parameterized and tested using thermal simulation models of the building.
Control Strategies of Decentralized Façade Ventilation Units
The fans for supply and exhaust air are working by speed control. Thereby, the flow rate can be adjusted to the actual fresh air demand, as computed from the sensor data air humidity, CO₂ and VOC. The air-conditioning process is working with an adaptive heat recovery system. This system provides the possibility to either recover heating (or cooling) energy or to bypass the heat exchanger, if ambient air can be used for air-conditioning. Additional water based cooling and heating devices are available as a backup system. A Software-in-the-Loop concept has been developed in order to optimize the control strategy.
Exergy-optimized Operational Management
The operation of the building and its technical equipment will be analyzed using an exergy-based analytical technology which, in particular, involves sensible utilization chains for energy transformation. This method enables a thermodynamically valid evaluation of the entire energy supply chain – starting from supply structure and energy transformation chain extending down to the energy streams within a building. The guiding principle of developing and later on optimizing a control strategy using and exergy-based approach is the exergy consumption minimization of each system component. Finding an adequate reference point and determining corresponding formulas for the exergy consumption of different components will contribute to the state of the art development in the exergy field.