Editing British thermal unit (section)

===Prefixes===
Units of kBtu are used in building energy use tracking and heating system sizing. Energy Use Index (EUI) represents kBtu per square foot of conditioned floor area. "k" stands for 1,000.<ref>{{cite web|title=VOLUNTARY BUILDING ENERGY PERFORMANCE SCORE SYSTEMS|website=Oregon Secretary of State Administrative Rules|url=https://secure.sos.state.or.us/oard/displayDivisionRules.action?selectedDivision=1091}}</ref>

The unit '''MBtu''' is used in natural gas and other industries to indicate 1,000 Btu.<ref name="EIA"/><ref name="Price">{{cite book |last=Price |first=Gary D. |title=Power Systems and Renewable Energy: Design, Operation, and Systems Analysis |publisher=Momentum Press |date=2014 |page=98 |isbn=9781606505717 |url=https://books.google.com/books?id=skICBAAAQBAJ&pg=PP9}}</ref> However, there is an ambiguity in that the metric system (SI) uses the prefix "M" to indicate '[[Mega-]]', one million (1,000,000). Even so, "MMBtu" is often used to indicate one million Btu particularly in the oil and gas industry.<ref name="APS">{{cite web |title=Energy Units |url=https://www.aps.org/policy/reports/popa-reports/energy/units.cfm |publisher=[[American Physical Society]] |access-date=26 December 2016 |url-status=live |archive-url=https://web.archive.org/web/20161231123621/http://www.aps.org/policy/reports/popa-reports/energy/units.cfm |archive-date=31 December 2016}}</ref>

Energy analysts accustomed to the metric "k" ('[[kilo-]]') for 1,000 are more likely to use MBtu to represent one million, especially in documents where M represents one million in other energy or cost units, such as MW, MWh and $.<ref>Cook, Warren C (2018): https://betterbuildingssolutioncenter.energy.gov/sites/default/files/attachments/Home%20Energy%20Score%20Report%20Example.pdf 
 https://www.oregon.gov/energy/Data-and-Reports/Documents/BER-Chapter-1-Energy-Numbers.pdf</ref>

The unit '[[therm]]' is used to represent 100,000 Btu.<ref name="EIA">{{cite web|url=http://www.eia.gov/tools/faqs/faq.cfm?id=45&t=8|title=What are Mcf, Btu, and therms? How do I convert prices in Mcf to Btus and therms?|publisher=[[Energy Information Administration|U.S. Energy Information Administration]]|date=6 April 2016|access-date=30 December 2016|url-status=live|archive-url=https://web.archive.org/web/20161225220005/http://www.eia.gov/tools/faqs/faq.cfm?id=45&t=8|archive-date=25 December 2016}}</ref> A decatherm is 10 therms or one million Btu. The unit ''[[quad (unit)|quad]]'' is commonly used to represent one quadrillion (10<sup>15</sup>) Btu.<ref name="APS"/>