Assessing the energy consumption of hospitals through simulation and measurements

Like many other commercial buildings, hospitals offer a considerable potential for energy savings. This is due to oversized systems, non-ideal operating conditions and other aspects. However, the complexity and diversity of consumers and systems as well as a lack of data make it difficult to evaluate the energy performance and estimate saving potentials. One option for the assessment of energy conservation measures is the realization of a building energy simulation. This can help to get a better understanding of the distribution of energy consumption throughout the building as well as the effectiveness of different energy saving measures that can be ""tested"" in the simulation. In a project of Fraunhofer UMSICHT a dynamic building energy simulation tool is created. The tool is designed in Modelica, a modeling language that is well suited to model complex buildings due to its object-oriented nature and flexibility. The model is built in a modular way: typical energy-relevant elements of a hospital are identified and pre-defined. Outputs of the model are for instance electricity or heating energy demand of the building. The tool is then deployed and tested by simulating two different hospitals. In order to collect input and validation data, comprehensive measurements are carried out. Since information about energy consumption of medical equipment as well as information about usage schedules of equipment is rare, numerous short-time measurements at equipment and department level are realized. Together with measurements at plant level they serve as input data for the model and provide information about the composition of the energy consumption. Measurements of electricity and thermal energy consumption are used for validation and calibration. Simulated results of subcomponents and the entire model are compared with real building consumption data to ensure that the calculated results represent the building in an accurate way.