Energy Monitoring
Contact
The monitoring system allows the users to see beneath the surface of the building, offering a better understanding of how the building and its technical equipment work and how it can be improved. Different types of data can be collected by a complex network of sensors, for example weather data like outside air temperature and global radiation, indoor comfort data like CO2- concentration and air humidity, energy data like flow and return temperatures of the concrete core activation circuits. This information can be used to identify problems in the operation of the technical equipment. Furthermore, they can be used to validate the thermal simulation models for the building. Using these models, new control strategies can be tested before applying them in the actual building.
Monitoring-System
A four layer monitoring system has been integrated. First, the gross supply of gas, electricity and renewable energy to the building is measured. Second, energy fluxes and thermal conditions around energy conversion units; like heat pumps, combined heat and power plants, sorption-supported air-conditioning etc. are observed. Third, energy fluxes are taken separately by energy distribution principles, e.g. concrete core activation, façade ventilation units, active chilled beams etc. Fourth, an extensive monitoring in ten reference rooms in different zones, e.g. different geographical orientation, different use, different energy conversion principle, is installed.
Integration
Three different sources deliver data that can be used for monitoring purposes. 86 facade ventilation units deliver eleven values each. The above mentioned user-installed monitoring system provides about 200 data points altogether. The building management system delivers more than 800 data objectives via OPC server integrated in the SCADA system. Moreover, system status information like switch-Booleans as well as control parameters and set values are taken. The data is centrally stored in a SQL data base. It can be accessed for system maintenance, malfunction analysis, simulation validation, building optimization or further thinkable energy and comfort related statistics.
Results
The Energy Concept of the new E.ON ERC Main Building is based on a geothermal energy and heat displacement in connection with a heat pump process. The correct operation of the geothermal field presents a complex problem, because the overall energy balance has to be zero. The monitoring data gives information about exactly how much energy was extracted from the field, and how much was injected back in. Monitoring of the heat pump allows for correct calculations of the COP and highlights potentials of improving it. Figure 4 shows the measurements for flow and return temperature, as well as heat flow from the geothermal field. The temperature difference between flow and return over the field is about 0.5 K. This leads to a heat flow between 20-25 kW during office hours, and then decreases around 11 kW in the night setback period.
Monitoring of Geothermal Probes
The energy flows inside the geothermal probe field are measured by different methods. The energy flow from every probe into the building is measured by metering the mass flow and the temperatures of the supplying and returning brine. Additionally, the thermal condition of each probe is measured with distributed temperature sensing (DTS) cables. With these DTS cables, the temperature distribution inside the probe can be measured along the total probe of length with a spatial resolution of 0.2 m. The third measurement method is the electrical resistivity tomogram of two geothermal probes. With this method, the temperature distribution of the whole probe field can be evaluated.