Analysis of the Energy Performance of Residential Inverter- Driven Heat Pumps
The energy performance of heat pumps is usually declared by manufacturers in particular conditions. However, the energy consumption of heat pumps depends on real operating conditions and on key choices done at the design stage. In practice, the heat pump operates for large annual time at partial loads and in transient regime. These behaviours, together with the domestic hot water production (if provided) and the defrosting cycles (in air to water heat pumps), affect the energy performance of the machine. In this paper, the real heat pumps performance is compared with a simplified modelling approach to evaluate the energy consumptions of the machines using data declared by manufacturers and with the reference Standard. To this purpose, the dataset reporting the operating conditions of ten installations made available by the open-source initiative HeatpumpMonitor is considered. Both air to water and ground source heat pumps are analysed. Two of these machines are compared in detail using the measured values, dividing the monitored data into stable conditions and transitory states. Then, the seasonal performance of the ten installations is compared with the corresponding value provided by manufacturers using the reference Standard. Finally, the simplified model is trained using the data declared by the manufacturers for four of the selected heat pumps in full and partial load operations. The model shows a relative mean error of 4% ranging between -8% and +14% in stable operations, and 6%, varying between -5% and 18% when all operative conditions are considered.