For buildings including temperature and humidity control, this study compares the energy prediction accuracy of a ZABES-model (Zone Air Building Energy Simulation) to an IBES-model (Integral Building Energy Simulation), which additionally includes models of the air handling unit (AHU) and controllers. Museum Hermitage Amsterdam served as a case study. For one year, measurements were performed in the main exhibition hall and its AHU. The ZABES-model was developed using heat air and moisture model for building and systems evaluation (implemented in MATLAB). The IBES-model was developed in Simulink and consists of the ZABES-model and models of AHU-components and controllers. Both models have been validated in detail. The IBES-model’s energy prediction errors are well within 10%. However, the ZABES-model underestimated the total annual energy consumption by 84%. Moreover, including occupants’ heat and moisture gains leads to realistic results using the IBES-model, but leads to unrealistic results using the ZABES-model. In conclusion, IBES-models are essential for reliable energy predictions of buildings including humidity control.