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With the implementation of the European Union (EU) Energy-related Products (ErP) Directive, heat pumps (HPs) and in particular air-to-water heat pumps (AWHPs), are expected to be widely installed in heating systems of residential and of the tertiary sector buildings. Heat pumps are nowadays regarded as a key technology for achieving the EU strategy towards nearly Zero Energy Buildings (nZEBs) and for reducing the fossil primary energy consumption and the related CO2 emissions. The awareness of HPs seasonal efficiency, which is affected by multiple parameters, is very important for choosing the best heat pump technology and the right equipment in a heating or cooling installation. The aim of this paper is to provide the Seasonal Coefficient of Performance (SCOP) of various AWHPs available in the Greek market from various manufacturers and installed in buildings located in the four Greek climate zones (A, B, C, D). The calculations are performed according to EN 14825 by using temperature data of four representative cities, one for each zone. Numerical results show the influence of various parameters, like HP’s compressor technology, water outlet temperature, and weather compensation to SCOP value, and highlight the importance of climate data for the accuracy of seasonal performance estimation.

Air-to-water heat pumps (AWHPs) are devices that will broadly replace heating systems based on fossil fuels. The performance of AWHPs in heating operation is strongly influenced by various parameters such as the climate of the location, the hot water output temperature to the heat emitters, the oversizing or downsizing of the HP with respect to the thermal load of the building, the control system, and the heat pump’s compressor technology (fixed-capacity and inverter-driven HPs). The aim of this work is to study the impact of those parameters on the seasonal efficiency for heating of AWHPs in buildings at representative cities of the four Greek climatic zones. The active mode seasonal coefficient of performance (SCOPon) was estimated in various case studies, with the method proposed in European standard EN 14825, by using climatic data of the four locations. The results show the positive effect of lowering the water supply temperature to the heating system and of using inverter technology and control system with compensation on AWHPs efficiency. Additionally, it is demonstrated that the optimal performance of inverter-driven HPs appears when they are sized at the design outdoor air temperature, while in the case of the fixed-capacity HPs when they are down-sized.

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Air-to-water heat pumps (AWHPs) is a very good option for efficient heating in the residential and commercial building sectors. Their performance and therefore the use of primary energy and CO2 gas emissions are affected by various factors. The aim of this paper is to present a study on the seasonal coefficient of performance in heating (SCOP) of AWHPs, which are available in the Greek market. The sample consists of 100 models in total, offered by 12 manufacturers, in a range of heat pump’s thermal capacity up to 50 kW. The calculation of SCOP values was performed according to the methodology proposed by the EN14825 standard. The results indicate how the heating capacity, the local climate, the supply water temperature, the compressor’s technology, and the control system affect the seasonal performance of the various AWHP models examined. Setting the SCOP ≥ 3 value as a criterion, the analysis that was carried out in four climatic zones A, B, C, and D of Greece, shows that there are many models that meet this criterion, and, in fact, their number increases from the coldest to warmer climates, in combination with lower water supply temperatures to the heating system and a control system with weather compensation.