A database study has found that air-to-water heat pumps using propane (R290) are already commercially available on the German and EU market and have high energy efficiency compared to competitors.
The study sought to identify the COP of the heat pumps and found that R290 air-to-water (ATW) units were amongst the top performers. However, in terms of energy performance, all the heat pumps with low-GWP refrigerants are similar, with differences in terms of decimals, according to the study.
The analysis was conducted by a consortium of German universities and consultancies and published in the International Energy Agency Heat Pumping Technologies Technical Collaboration Programme’s (IEA HPT TCP) 2021 Progress Annual Report, HPT Annex 54 Tasks 1, 2 and 3 on low-GWP heat pump systems. The study is part of the German contribution to the yearly deliverable for this workstream.
The German market analysis looked at a database for heat pumps published by the Federal Office for Economic Affairs and Export Control (BAFA) in December 2020. The list includes all heat pumps available on the German market and their respective COPs, but only ATW heat pumps were considered.
The analysis identified 13 different refrigerants and found that R290 ATW heat pump units consistently show higher COP than f-gas equipment. The COP values for the R290 ATW units vary from slightly under 3 for the lowest ambient temperature to 6 for warmer conditions. The performances were calculated with different ambient temperatures (i.e., -7, 2, 7 and 10°C, or 19.4, 35.6, 44.6 and 50°F), but with the same target water temperature (35°C, or 95°F), which is typical of a wet-based underfloor system.
The authors also found that in 2019 the sales of R290 ATW heat pumps surpassed R32 units, representing 8.6% of the sold stock, according to data analyzed from the market incentive program (MAP) managed by the German federal government. R32-based units represented 2.6%, whereas R407C and R410A together constituted the majority.
Finally, the study’s authors analyzed the HP Keymark database covering the EU market. The analysis was limited to ATW heat pumps and further narrowed down to medium temperature applications, with supply temperatures of 35 and 55°C (131°F). The data shows that the R290 ATW heat pumps were, once again, among the top performers, with an average COP of 4.7 at 35°C – with some units performing above 5.0 – and an average COP of 3.1 at 55°C.
The Heat Pump Keymark is a voluntary, independent European certification mark (ISO type 5 certification) for heat pumps, combination heat pumps and hot water heaters, as covered by the Ecodesign Directive. It is based on third-party testing and it is owned by the European Committee for standardization (CEN).
Natref HP ecolabel – Blue Angel expected soon
The European Commission has recently released its EU F-Gas revision proposal, which introduces bans on stationary AC systems and heat pumps; split systems below 12 kW using refrigerants with GWP higher than 150 and single split systems containing less than 3 kg (6.6lbs) of a fluorinated refrigerant with GWP above 750 will be phased out as of January 1, 2025. Split systems delivering higher outputs than 12 kW will have to use a refrigerant below 750 as of January 1, 2027. These bans are likely to favor the uptake of equipment using hydrocarbons, if the proposal is ultimately translated into law.
Domestic heat pump systems using R290 have also been found to have a lower impact on the climate than their f-gas counterparts, according to another study featuring the IEA HPT Annex 54 2021 Annual Report.
Given the relevance of heat pumps for decarbonization efforts, the German Environment Agency is planning to launch a new Blue Angel ecolabel for heat pumps. The Blue Angel is a voluntary ecolabel that aims to help consumers identify the most environmentally friendly products in a certain product group. To assist in this effort, German consultancy HEAT GmbH is working to draft criteria for the rating of heat pumps and has reported that the use of natural refrigerants will be among the criteria, according to the IEA HPT Annex 54 2021 Annual Report.
High energy efficiency will be the second criterion, according to the report. The interim report is expected to be released in the first part of 2022.
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