Abstract The need for energy labelling procedures applied to thermal systems requires new methods to assess their seasonal performance. Their typical dynamic operation and the interaction among components and control system restrict the possible use of stationary, component-oriented tests. New dynamic test methods addressing the system as a whole are now available in the open literature. Discussion is undergoing with respect to key issues such as test sequence definition and post-processing of the test results. A new dynamic procedure was developed to address these points, based on the statistical selection of the test boundary conditions. The paper describes the procedure and its first validation at component level. The results of the dynamic test were compared with the values obtained for the entire season operation, showing a good agreement both in terms of seasonal performance figures and of instantaneous distributions of the performance indicators. The promising results obtained so far to motivate the application of the procedure to other components and a future adaption to test whole systems.