This article aims to investigate the influence of climate conditions and occupancy levels on the energy savings potential of a novel hydronic circuit configuration in active beam systems. This configuration consists of a room-temperature water loop, which delivers water at a temperature of 22 °C to all the zones in a building. An inherent characteristic of the circuit is that excess heat can be transferred from warm to cold zones when simultaneous need of heating and cooling occurs in the building. This process leads to a reduction of the annual energy use when comparing the novel configuration with traditional ones. The amount of energy reduction depends on the diversity of thermal loads applied to different zones in the building, which are mainly due to climate conditions and occupancy. Therefore, to capture the influence of these two factors on the heat transfer potential of the water loop, a parametric analysis was performed. Three climate locations and five occupancy levels were considered in a model of the system developed in Dymola. Simulation results show that heat transfer between zones leads to annual energy savings of between 7% and 27%, depending on the scenario considered. In absolute terms, the energy savings were between 1.6 kWh/m² and 6.4 kWh/m².

This paper proposes an active beam model suitable for building energy simulations with the programming language Modelica. The model encapsulates empirical equations derived by a novel active beam terminal unit that operates with low-temperature heating and high-temperature cooling systems. Measurements from a full-scale experiment are used to compare the thermal behavior of the active beam with the one predicted by simulations. The simulation results show that the model corresponds closely with the actual operation. The model predicts the outlet water temperature of the active beam with a maximum mean absolute error of 0.18 °C. In term of maximum mean absolute percentage error, simulation results differ by 0.9%. The methodology presented is general enough to be applied for modeling other active beam units.