Editing Concrete (section)

===Energy efficiency===
The cement produced for making concrete accounts for about 8% of worldwide {{CO2}} emissions per year (compared to, ''e.g.'', global aviation at 1.9%).<ref name=chathamhouse>{{Cite web|url=https://reader.chathamhouse.org/making-concrete-change-innovation-low-carbon-cement-and-concrete |title=Making Concrete Change: Innovation in Low-carbon Cement and Concrete|website=Chatham House|date=13 June 2018|access-date=17 December 2018 |archive-url=https://web.archive.org/web/20181219161129/https://reader.chathamhouse.org/making-concrete-change-innovation-low-carbon-cement-and-concrete |archive-date=19 December 2018 |url-status=live}}</ref> The two [[Cement#CO2 emissions|largest sources]] of {{CO2}} are produced by the cement manufacturing process, arising from (1) the decarbonation reaction of [[limestone]] in the [[cement kiln]] (T ≈ 950&nbsp;°C), and (2) from the combustion of [[fossil fuel]] to reach the [[sintering]] temperature (T ≈ 1450&nbsp;°C) of [[cement clinker]] in the kiln. The energy required for extracting, crushing, and mixing the raw materials ([[construction aggregate]]s used in the concrete production, and also [[limestone]] and [[clay]] feeding the [[cement kiln]]) is lower. Energy requirement for transportation of [[ready-mix concrete]] is also lower because it is produced nearby the construction site from local resources, typically manufactured within 100 kilometers of the job site.<ref>{{cite web|last1=Rubenstein|first1=Madeleine|date=9 May 2012|title=Emissions from the Cement Industry|url=http://blogs.ei.columbia.edu/2012/05/09/emissions-from-the-cement-industry/|url-status=live|archive-url=https://web.archive.org/web/20161222053719/http://blogs.ei.columbia.edu/2012/05/09/emissions-from-the-cement-industry/|archive-date=22 December 2016|access-date=13 December 2016|website=State of the Planet|publisher=Earth Institute, Columbia University}}</ref> The overall [[embodied energy]] of concrete at roughly 1 to 1.5 megajoules per kilogram is therefore lower than for many structural and construction materials.<ref>{{cite web|date=22 February 2013|title=Concrete and Embodied Energy – Can using concrete be carbon neutral|url=http://strineenvironments.com.au/factsheets/concrete-and-embodied-energy-can-using-concrete-be-carbon-neutral/|url-status=live|archive-url=https://web.archive.org/web/20170116174733/http://strineenvironments.com.au/factsheets/concrete-and-embodied-energy-can-using-concrete-be-carbon-neutral/|archive-date=16 January 2017|access-date=15 January 2017}}</ref>

Once in place, concrete offers a great energy efficiency over the lifetime of a building.<ref>{{cite web|last1=Gajda|first1=John|year=2001|title=Energy Use of Single-Family Houses with Various Exterior Walls|url=https://www.healthyheating.com/Page%2055/Downloads/Wall_Systems.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.healthyheating.com/Page%2055/Downloads/Wall_Systems.pdf |archive-date=2022-10-09 |url-status=live}}</ref> Concrete walls leak air far less than those made of wood frames.<ref>{{cite book|title=Green Building with Concrete|year= 2015|publisher=Taylor & Francis Group|isbn=978-1-4987-0411-3}}{{page needed|date=October 2021}}</ref> Air leakage accounts for a large percentage of energy loss from a home. The thermal mass properties of concrete increase the efficiency of both residential and commercial buildings. By storing and releasing the energy needed for heating or cooling, concrete's thermal mass delivers year-round benefits by reducing temperature swings inside and minimizing heating and cooling costs.<ref name="Features and Usage of Foam Concrete">{{cite web|title=Features and Usage of Foam Concrete|url=http://www.chinaconcretepump.com/Foam-Concrete-Machine.html/|archive-url=https://archive.today/20121129122814/http://www.chinaconcretepump.com/Foam-Concrete-Machine.html/|archive-date=29 November 2012}}</ref> While insulation reduces energy loss through the building envelope, thermal mass uses walls to store and release energy. Modern concrete wall systems use both external insulation and thermal mass to create an energy-efficient building. Insulating concrete forms (ICFs) are hollow blocks or panels made of either insulating foam or [[rastra]] that are stacked to form the shape of the walls of a building and then filled with reinforced concrete to create the structure.