Multi-Mode Model of an Air Handling Unit for Thermal Demand Calculations in Modelica

This paper describes a simulation model to calculate thermal energy demand of air handling units (AHU) centrally installed in buildings with focus on laboratories. The model’s design gradually supports energy demand calculations of multiple buildings, e.g. on district level. The AHU is modelled in the open source, object-oriented modelling language Modelica ® . The model uses particular operation modes while neglecting dynamic transitions as this reduces computational effort to allow simulations on district level. A comparison of simulation results to experimental results, gained with a test bed at the Institute for Energy Efficient Buildings and Indoor Climate, RWTH Aachen University gives insights into the model’s accuracy. The results justify using the model in district simulations, where reduced calculation efforts outweigh acceptable deviations. Moreover, this paper presents thermal demand simulations of a research site with 195 buildings and a comparison to monitoring data. The computed hourly heating power is satisfying compared to this measured data, e.g. in terms of the coefficient of determination with a value of R2 = 0.939.