Editing Heat pump (section)

==Applications==
The [[International Energy Agency]] estimated that, as of 2021, heat pumps installed in buildings have a combined capacity of more than 1000 GW.<ref name="ieareport" /> They are used for [[heating, ventilation, and air conditioning]] (HVAC) and may also provide domestic hot water and tumble clothes drying.<ref>{{cite web|url = http://energy.gov/energysaver/heat-pump-systems|title = Heat Pump Systems|publisher = U.S. Department of Energy|access-date = 2016-02-05|archive-date = 2017-07-04|archive-url = https://web.archive.org/web/20170704201055/https://energy.gov/energysaver/heat-pump-systems|url-status = live}}</ref> The purchase costs are supported in various countries by consumer rebates.<ref>{{cite web|url =http://www.gshp.org.uk/RHI_Domestic.html|title =Renewable Heat Incentive – Domestic RHI – paid over 7 years|website =Ground Source Heat Pump Association|access-date =2017-03-12|archive-date =2018-03-08|archive-url =https://web.archive.org/web/20180308103938/http://www.gshp.org.uk/RHI_Domestic.html|url-status =live}}</ref>

===Space heating and sometimes also cooling===
In HVAC applications, a heat pump is typically a [[vapor-compression refrigeration]] device that includes a [[reversing valve]] and optimized heat exchangers so that the direction of ''heat flow'' (thermal energy movement) may be reversed. The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling to a building.

Because the two heat exchangers, the condenser and evaporator, must swap functions, they are optimized to perform adequately in both modes. Therefore, the [[SEER|Seasonal Energy Efficiency Rating]] (SEER in the US) or [[European seasonal energy efficiency ratio]] of a reversible heat pump is typically slightly less than those of two separately optimized machines. For equipment to receive the [[Energy Star|US Energy Star]] rating, it must have a rating of at least 14 SEER. Pumps with ratings of 18 SEER or above are considered highly efficient. The highest efficiency heat pumps manufactured are up to 24 SEER.<ref>{{Cite web |title=Heat Pump Efficiency {{!}} Heat Pump SEER Ratings |url=https://www.carrier.com/residential/en/us/products/heat-pumps/heat-pump-efficiency/ |access-date=2023-01-14 |website=Carrier |language=en |archive-date=2023-01-14 |archive-url=https://web.archive.org/web/20230114133418/https://www.carrier.com/residential/en/us/products/heat-pumps/heat-pump-efficiency/ |url-status=live }}</ref>

[[Heating seasonal performance factor]] (in the US) or [[Seasonal Performance Factor]] (in Europe) are ratings of heating performance. The SPF is Total heat output per annum / Total electricity consumed per annum in other words the average heating COP over the year.<ref>{{Cite web |date=2019-11-07 |title=COP and SPF for Heat Pumps Explained |url=https://greenbusinesswatch.co.uk/cop-vs-spf |access-date=2024-02-22 |website=Green Business Watch UK |language=en-GB}}</ref>

====Window mounted heat pump====
[[File:Window heat pump.webp|thumb|Saddle-style window mounted heat pump 3D sketch]]
Window mounted heat pumps run on standard 120v AC outlets and provide heating, cooling, and humidity control. They are more efficient with lower noise levels, condensation management, and a smaller footprint than [[Packaged terminal air conditioner|window mounted air conditioners]] that just do cooling.<ref>{{cite web |date=11 June 2024 |title=Why This Window Heat Pump is Genius – Undecided with Matt Ferrell |url=https://undecidedmf.com/why-this-window-heat-pump-is-genius/}}</ref>

===Water heating===
In [[water heating]] applications, heat pumps may be used to heat or preheat water for swimming pools, homes or industry. Usually heat is extracted from outdoor air and transferred to an indoor water tank.<ref>{{Cite web |title=How it Works — Heat Pump Water Heaters (HPWHs) |url=https://www.energystar.gov/products/water_heaters/high_efficiency_electric_storage_water_heaters/how_it_works |access-date=2024-01-22 |website=www.energystar.gov |language=en}}</ref><ref>{{Cite web |title=Heat-pump hot water systems |url=https://www.sustainability.vic.gov.au/energy-efficiency-and-reducing-emissions/save-energy-in-the-home/water-heating/choose-the-right-hot-water-system/heat-pump-water-heaters |access-date=2024-01-22 |website=Sustainability Victoria |language=en}}</ref>

===District heating===
Large (megawatt-scale) heat pumps are used for [[district heating]].<ref>{{Cite news |last=Baraniuk |first=Chris |date=2023-05-29 |title=The 'exploding' demand for giant heat pumps |language=en-GB |work=[[BBC News]] |url=https://www.bbc.com/news/business-65321487 |access-date=2023-09-17 |archive-date=2023-09-07 |archive-url=https://web.archive.org/web/20230907053141/https://www.bbc.com/news/business-65321487 |url-status=live }}</ref> However {{As of|2022|lc=y}} about 90% of district heat is from [[fossil fuel]]s.<ref>{{Cite web |title=District Heating – Energy System |url=https://www.iea.org/energy-system/buildings/district-heating |access-date=2024-01-22 |website=IEA |language=en-GB}}</ref> In Europe, heat pumps account for a mere 1% of heat supply in district heating networks but several countries have targets to decarbonise their networks between 2030 and 2040.<ref name=ieareport /> Possible sources of heat for such applications are [[sewage]] water, ambient water (e.g. sea, lake and river water), industrial [[waste heat]], [[geothermal energy]], [[flue gas]], waste heat from [[district cooling]] and heat from solar [[seasonal thermal energy storage]].<ref name="David">{{cite journal |last1=David |first1=Andrei|display-authors=etal |date=2017 |title=Heat Roadmap Europe: Large-Scale Electric Heat Pumps in District Heating Systems |journal=[[Energies]] |volume=10 |issue= 4|pages=578 |doi=10.3390/en10040578 |doi-access=free }}</ref> Large-scale heat pumps for district heating combined with [[thermal energy storage]] offer high flexibility for the integration of [[variable renewable energy]]. Therefore, they are regarded as a key technology for [[Climate change mitigation|limiting climate change]] by [[Fossil fuel phase-out|phasing out fossil fuels]].<ref name="David" /><ref>{{cite journal |last1=Sayegh |first1=M. A. |display-authors=etal |date=2018 |title=Heat pump placement, connection and operational modes in European district heating |url=http://bura.brunel.ac.uk/handle/2438/15834 |url-status=live |journal=Energy and Buildings |volume=166 |pages=122–144 |doi=10.1016/j.enbuild.2018.02.006 |bibcode=2018EneBu.166..122S |archive-url=https://web.archive.org/web/20191214210133/http://bura.brunel.ac.uk/handle/2438/15834 |archive-date=2019-12-14 |access-date=2019-07-10}}</ref> They are also a crucial element of [[cold district heating|systems which can both heat and cool districts]].<ref>{{citation |author=Buffa |first=Simone |title=5th generation district heating and cooling systems: A review of existing cases in Europe |date=2019 |periodical=[[Renewable and Sustainable Energy Reviews]] |volume=104 |pages=504–522 |language=de |doi=10.1016/j.rser.2018.12.059 |display-authors=etal |doi-access=free|bibcode=2019RSERv.104..504B }}</ref>

===Industrial heating===
There is great potential to reduce the energy consumption and related greenhouse gas emissions in industry by application of industrial heat pumps, for example for [[process heat]].<ref>{{Cite web |title=Home |url=https://heatpumpingtechnologies.org/annex35/ |access-date=2024-02-22 |website=Annex 35 |language=en}}</ref><ref>{{Cite web |title=Industrial Heat Pumps: it's time to go electric |url=https://www.wbcsd.org/wgthg |access-date=2024-02-22 |website=World Business Council for Sustainable Development (WBCSD) |language=en-GB }}{{Dead link|date=March 2025 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Short payback periods of less than 2 years are possible, while achieving a high reduction of {{CO2}} emissions (in some cases more than 50%).<ref>[https://heatpumpingtechnologies.org/publications/?search=Annex+35 IEA HPT TCP Annex 35 Publications] {{Webarchive|url=https://web.archive.org/web/20180921153253/https://heatpumpingtechnologies.org/publications/?search=Annex+35 |date=2018-09-21 }}</ref><ref>{{Cite web |title=Application of Industrial Heat Pumps. Annex 35 two-page summary. |url=https://heatpumpingtechnologies.org/publications/application-of-industrial-heat-pumps-annex-35-two-page-summary/ |access-date=2023-12-28 |website=HPT – Heat Pumping Technologies |language=en}}</ref> Industrial heat pumps can heat up to 200&nbsp;°C, and can meet the heating demands of many [[Light industry|light industries]].<ref>{{Cite web |date=2021-08-05 |title=Norwegian Researchers Develop World's Hottest Heat Pump |url=https://ammonia21.com/norwegian-researchers-develop-worlds-hottest-heat-pump/ |access-date=2022-06-07 |website=Ammonia21 |language=en-US |archive-date=2022-05-23 |archive-url=https://web.archive.org/web/20220523024019/https://ammonia21.com/norwegian-researchers-develop-worlds-hottest-heat-pump/ |url-status=live }}</ref><ref>{{Cite web |title=Heat pumps are key to helping industry turn electric |url=https://www.wbcsd.org/3w9qh |access-date=2022-10-04 |website=World Business Council for Sustainable Development (WBCSD) |language=en-GB |archive-date=2023-09-24 |archive-url=https://web.archive.org/web/20230924115906/https://www.wbcsd.org/Pathways/Energy/News/Heat-pumps-are-key-to-helping-industry-turn-electric |url-status=live }}</ref> In Europe alone, 15&nbsp;GW of heat pumps could be installed in 3,000 facilities in the paper, food and chemicals industries.<ref name=ieareport />