{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,2]],"date-time":"2025-11-02T05:08:11Z","timestamp":1762060091913,"version":"build-2065373602"},"reference-count":50,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2022,8,2]],"date-time":"2022-08-02T00:00:00Z","timestamp":1659398400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"German Federal Ministry for Economic Affairs and Climate Action","award":["03ET1377 B","03SBE0001B"],"award-info":[{"award-number":["03ET1377 B","03SBE0001B"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Energies"],"abstract":"<jats:p>Unrenovated multifamily houses in Germany are mostly heated by fossil heat generators; therefore, measures are required for CO2 emission reduction. The use of air\u2013water heat pumps is restricted by high required flow temperatures and heat output but can be mitigated by hybrid heat pumps. To limit additional operation costs by the heat pump, a new operation strategy is introduced in this study, which allows to maintain a target CO2 emission. The operation strategy is applied in a field trial in a small unrenovated multifamily house built in 1964. A thermohydraulic simulation model is verified and is used in full-year simulations to apply improvement measures and compare the new control strategy with existing optimizing strategies. The results show that the control onto target emissions is possible and limits additional costs but can also result in higher CO2 mitigation costs, making it less favorable. The hybrid heat pump reduces the direct fossil CO2 emissions by 61% (in total by 22%); thus, it is a relevant solution for multifamily houses, especially within a further decarbonized electrical grid.<\/jats:p>","DOI":"10.3390\/en15155611","type":"journal-article","created":{"date-parts":[[2022,8,2]],"date-time":"2022-08-02T21:41:37Z","timestamp":1659476497000},"page":"5611","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Analysis of the Operation Characteristics of a Hybrid Heat Pump in an Existing Multifamily House Based on Field Test Data and Simulation"],"prefix":"10.3390","volume":"15","author":[{"given":"Daniel","family":"Neubert","sequence":"first","affiliation":[{"name":"Chair of Building Energy Systems and Heat Supply, Technische Universit\u00e4t Dresden, 01062 Dresden, Germany"},{"name":"Bosch Thermotechnik GmbH, 35457 Lollar, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christian","family":"Gl\u00fcck","sequence":"additional","affiliation":[{"name":"Bosch Thermotechnik GmbH, 35457 Lollar, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Julian","family":"Schnitzius","sequence":"additional","affiliation":[{"name":"Bosch Thermotechnik GmbH, 35457 Lollar, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Armin","family":"Marko","sequence":"additional","affiliation":[{"name":"Bosch Thermotechnik GmbH, 35457 Lollar, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jeannette","family":"Wapler","sequence":"additional","affiliation":[{"name":"Fraunhofer Institute of Solar Energy Systems ISE, 79110 Freiburg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Constanze","family":"Bongs","sequence":"additional","affiliation":[{"name":"Fraunhofer Institute of Solar Energy Systems ISE, 79110 Freiburg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Clemens","family":"Felsmann","sequence":"additional","affiliation":[{"name":"Chair of Building Energy Systems and Heat Supply, Technische Universit\u00e4t Dresden, 01062 Dresden, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,8,2]]},"reference":[{"key":"ref_1","unstructured":"Bundes-Klimaschutzgesetz (KSG) (2022, June 11). 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