Heat meter

{{Short description|Measuring device for thermal energy}} [[image:Wärmeübergabestation 300 kW.jpg|thumb|right|A heat meter attached to a heat exchanger in a district heating substation in a residential neighborhood in Austria. Right in white-blue: the calculator; in the center in bronze: the ultrasonic flow meter. ]] A '''heat meter''', '''thermal energy meter''', or '''BTU meter''' is a device that measures thermal energy provided by a source, such as a central heating system, by measuring the flow rate of the heat transfer fluid and the change in its temperature (ΔT) between the outflow and return legs of the system. Heat meters are used in district heating systems and other shared heating systems to measure heat delivered to residential and commercial tenants, which enables consumption-based billing (submetering). Heat meters are also used in industrial plants for measuring boiler output and heat taken by process.

== Elements == thumb|Heat meter with ultrasonic flow meter A heat meter consists of:<ref>{{Cite web |date=January 2019 |title=Fundamentals of Heat Metering in Hydronic Systems - Idronics 24 |url=https://www.caleffi.com/sites/default/files/media/external-file/Idronics_24_NA_Fundamentals%20of%20heat%20metering%20in%20hydronic%20systems.pdf |access-date=2025-11-19 |website=Caleffi |page=5-6 |language=en-us}}</ref>

# A fluid flow meter, typically a turbine flow meter or ultrasonic flow meter. # A means of measuring the temperature between the outflow and the inflow, usually a pair of thermocouples. # A means of integrating the two measurements over a period of time and accumulating the total heat transfer in a given period.

== Applications == thumb|Early mechanical heat meter Heat meters are commonly used in buildings served by district heating. Operators of multifamily residential buildings and multi-tenant commercial buildings with hydronic systems can also use heat meters to submeter tenant use of the system.<ref>{{Cite web |last=Harris |first=Angela D. |date=2019-07-15 |title=Heat Metering Makes Centralized Hydronic Heat a Viable Option |url=https://www.achrnews.com/articles/141568-heat-metering-makes-centralized-hydronic-heat-a-viable-option |access-date=2025-11-19 |website=ACHR News |language=en}}</ref>

In industrial plants, a thermal energy meter can be used to measure the cooling output from a chiller unit,<ref>{{Cite web |last=Rimler |first=Barry |date=February 20, 2013 |title=Sensors for Measuring Chilled Water Production and it's Uses |url=https://blog.se.com/datacenter/architecture/2013/02/20/sensors-measuring-chilled-water-production/ |access-date=19 November 2025 |website=Schneider Electric}}</ref> for example to monitor functionality and energy efficiency.<ref>{{Cite web |date=May 28, 2020 |title=Flow Monitoring in Process Cooling Applications |url=https://www.veris.com/blog/flow-monitoring-in-process-cooling-applications |access-date=19 November 2025 |website=Veris}}</ref>

Heat metering can be used in solar thermal collector systems to verify that the system is working correctly and quantify how much solar heat is collected.<ref>{{Cite web |last=Stickney |first=Bristol |date=October 25, 2017 |title=Heat Energy Measurement Around a Primary Loop |url=https://www.phcppros.com/articles/6257-heat-energy-measurement-around-a-primary-loop |access-date=2025-11-19 |website=PHCP Pros |language=en}}</ref> For example, an experimental solar water heating project in 1976 in Ocala, Florida, involved using heat meters to measure energy produced by the solar heaters.<ref>{{Cite news |date=1976-10-07 |title=Solar Energy To Be Used As Water Heater |url=https://www.newspapers.com/article/the-daytona-beach-news-journal-solar-ene/185299218/ |access-date=2025-11-20 |work=The Daytona Beach News-Journal |pages=17}}</ref>

== Regional practices and regulations == thumb|Example of heat meter installation === European Union === The European Union has encouraged per-tenant heat metering as an energy efficiency strategy since 2002, and it made heat metering mandatory in 2012 with the Energy Efficiency Directive 2012/27/EU.<ref>{{Cite journal |last1=Canale |first1=L. |last2=Dell'Isola |first2=M. |last3=Ficco |first3=G. |last4=Cholewa |first4=T. |last5=Siggelsten |first5=S. |last6=Balen |first6=I. |date=2019-11-01 |title=A comprehensive review on heat accounting and cost allocation in residential buildings in EU |url=https://www.sciencedirect.com/science/article/pii/S0378778819316883 |journal=Energy and Buildings |volume=202 |article-number=109398 |doi=10.1016/j.enbuild.2019.109398 |bibcode=2019EneBu.20209398C |issn=0378-7788}}</ref> This directive requires heat metering in multifamily residential buildings that use district heating or have a central heating system.<ref>{{Citation |last1=Fabrizio |first1=E. |last2=Ferrara |first2=M. |last3=Monetti |first3=V. |title=Smart Heating Systems for Cost-Effective Retrofitting |date=2017-01-01 |work=Cost-Effective Energy Efficient Building Retrofitting |pages=279–304 |url=https://www.sciencedirect.com/science/chapter/edited-volume/abs/pii/B9780081011287000101 |access-date=2025-11-19 |publisher=Woodhead Publishing |language=en-US |doi=10.1016/b978-0-08-101128-7.00010-1 |isbn=978-0-08-101128-7 |url-access=subscription }}</ref> For example, the United Kingdom requires operators of communal heating systems to submeter tenant heat use.<ref>{{Cite web |date=2023-12-18 |title=Heat meters |url=https://www.islington.gov.uk/housing/heat-meters |access-date=2024-02-22 |website=Islington Council |language=en}}</ref><ref>{{Cite web |date=2024-11-13 |title=Regulations: heat networks (metering and billing) |url=https://www.gov.uk/guidance/heat-networks |access-date=2025-11-19 |website=GOV.UK |language=en}}</ref> The goal is to reduce energy consumption by providing tenants a financial incentive to reduce heat consumption.<ref>{{Cite journal |last1=Morgenstern |first1=Paula |last2=Lowe |first2=Robert |last3=Chiu |first3=Lai Fong |date=2015-03-04 |title=Heat metering: socio-technical challenges in district-heated social housing |url=https://doi.org/10.1080/09613218.2014.932639 |journal=Building Research & Information |volume=43 |issue=2 |pages=197–209 |doi=10.1080/09613218.2014.932639 |bibcode=2015BuRI...43..197M |issn=0961-3218}}</ref>

In the European Union, heat meters need to comply with the Measuring Instruments Directive (MID) Annex VI MI-004 if the meters are used for custody transfer. For automatic meter reading, they use the Meter-Bus standard.

=== United States and Canada === Heat meters are typically called BTU meters in the United States and Canada. They were commercially available in the United States as early as 1958, under the brand name Pollux BTU Meter.<ref>{{Cite news |date=1958-09-09 |title=New Device Tells Heat Absorption; Instrument Also Measures Amount of Cooling -- Use in Shopping Mart Cited |url=https://www.nytimes.com/1958/09/09/archives/new-device-tells-heat-absorption-instrument-also-measures-amount-of.html |access-date=2025-11-20 |work=The New York Times |language=en}}</ref> As of the late 2010s and early 2020s, they are uncommon in the United States and Canada, but there is growing interest due to increasing energy costs and requirements to reduce carbon emissions.<ref name=":0">{{Cite web |last=Siegenthaler |first=John |date=March 7, 2019 |title="Pay for what you use" heat metering technology gains traction |url=https://www.hpacmag.com/features/heat-meter-technology-gains-traction/ |access-date=2025-11-19 |website=HPAC Magazine |language=en-US}}</ref><ref>{{Cite web |last=Caswell |first=Logan |date=June 25, 2021 |title=Benefits of Energy Metering |url=https://www.hpacmag.com/features/benefits-of-energy-metering/ |access-date=2025-11-19 |website=HPAC Magazine |language=en-US}}</ref>

The relevant standard is ASTM E3137/E3137M-18, "Standard Specification for Heat Meter Instrumentation", released in 2018.<ref name=":0" /><ref>{{Cite web |date=August 8, 2018 |title=Standard Specification for Heat Meter Instrumentation |url=https://store.astm.org/e3137_e3137m-18.html |access-date=2025-11-19 |website=ASTM |language=en}}</ref>

=== China === Northern China has a significant number of large residential buildings with district heating.<ref name=":1">{{Cite journal |last1=Luo |first1=Ao |last2=Li |first2=Chunyang |last3=Xia |first3=Jianjun |last4=Cheng |first4=Pengyue |date=2024-01-25 |title=Thermal Characteristics and User Regulation of Household Heat Metering for Residential District Heating Systems in Northern China |journal=Energies |language=en |volume=17 |issue=3 |pages=579 |doi=10.3390/en17030579 |doi-access=free |issn=1996-1073 }}</ref> As early as 2003, policymakers recommended meter-based heat pricing to improve the efficiency and sustainability of district heating, as part of larger heat reform initiatives.<ref>{{Cite journal |last1=Wang |first1=Manyu |last2=Huang |first2=Ying |last3=An |first3=Zidong |last4=Wei |first4=Chu |date=2023-01-01 |title=Reforming the world's largest heating system: Quasi-experimental evidence from China |url=https://www.sciencedirect.com/science/article/pii/S0140988322005461 |journal=Energy Economics |volume=117 |article-number=106417 |doi=10.1016/j.eneco.2022.106417 |bibcode=2023EneEc.11706417W |issn=0140-9883|url-access=subscription }}</ref> By 2015, 32 million heat meters were installed in buildings in urban areas of northern China.<ref>{{Cite web |date=2017 |title=District Energy Systems in China: Options for optimisation and diversification |url=https://iea.blob.core.windows.net/assets/590cc681-349a-4a55-9d3f-609eff6cde0b/DistrictEnergySystemsinChina.pdf |access-date=2025-11-20 |website=International Energy Agency (IEA) |page=16, 20 |language=en-GB}}</ref> As of 2024, relatively few buildings charged for per-household heat usage based on heat meters, but there was interest in improving the quality and distribution of heat metering.<ref name=":1" />

=== Russia === District heating is common in Russia, serving 73% of the population as of 2010.<ref name=":2">{{Cite journal |last=Korppoo |first=Anna |last2=Korobova |first2=Nina |date=2012-03-01 |title=Modernizing residential heating in Russia: End-use practices, legal developments, and future prospects |url=https://www.sciencedirect.com/science/article/pii/S0301421511009761 |journal=Energy Policy |volume=42 |pages=213–220 |doi=10.1016/j.enpol.2011.11.078 |issn=0301-4215|url-access=subscription }}</ref> At that time, between 10-25% of private houses and apartments with district heating had heat meters, along with 40% of public buildings.<ref name=":2" />

==References== {{reflist}}

Category:Thermometers