• Energy Research

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.

Abstract The performance of heating and cooling systems are affected by their dynamic operating conditions. As a consequence, a sound evaluation of system performance should be done through a dynamic test procedure. However, the complexity, the cost, and the time for such type of experimentation are obstacles to the diffusion of this test method. A new whole system test procedure was developed to reduce its potential failure. The test method considers the emulation of system components that cannot be installed in the laboratory, while the selection of short-yet-significant test sequence is performed classifying the days of the year with clustering analysis. The procedure was applied to a solar-assisted heat pump system in four different European climates. The seasonal performance figures are extrapolated from the test results and compared with the numerical simulations of the entire heating and cooling system. In all test cases the seasonal performance factors are lower than the simulated ones by approximately 10%. The results obtained with dynamic tests confirm the necessity of their implementation, since they provide useful information to improve the system layout and control. In this way, the manufacturers can introduce more efficient products into the market.

Direct characterisation of the annual performance of solar thermal and heat pump systems using a six-day whole system test

In the EU 28, the installed heating appliance stock is quite old, with an actual replacement rate of 4%. This is directly reflected in the average efficiency of the installed heating systems, where around 60% of the stock is rated with an energy class of C or D (the lowest classes of the energy label scale). The European project HARP aims at raising consumers’ awareness of the planned replacement of their old and inefficient heating appliances with more efficient and renewable solutions. In this direction, an energy labeling methodology for old appliances has been developed to rate the installed stock before the introduction of the EU energy label. The methodology has been developed for space heating appliances and water heaters, targeting two types of users: end consumers and professional users. The validation considered about 4600 space heating appliances and 800 water heaters built between 1972 and 2019. Three heating appliances and two water heaters were tested in the laboratory, confirming the reliability of the proposed methodology. The expected impact of defining an energy labeling methodology for installed heating appliances increases the current replacement rate of these appliances in the EU from 4% to 5%.