Editing IPCC:AR6/WGIII/Chapter-9 (section)

==== 9.4.2.1 Embodied Energy and Embodied Carbon in Building Materials ====

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As building energy demand is decreased the importance of embodied energy and embodied carbon in building materials increases ( [[#Ürge-Vorsatz--2020|Ürge-Vorsatz et al. 2020]] ). Buildings are recognised as built following five building frames: concrete, wood, masonry, steel, and composite frames (International Energy Agency 2019a); but other building frames should be considered to include worldwide building construction practice, such as rammed earth and bamboo in vernacular design ( [[#Cabeza--2021|Cabeza et al. 2021]] ).

The most prominent materials used following these frames classifications are the following. Concrete, a man-made material, is the most widely used building material. Wood has been used for many centuries for the construction of buildings and other structures in the built environment; and it remains as an important construction material today. Steel is the strongest building material; it is mainly used in industrial facilities and in buildings with big glass envelopes. Masonry is a heterogeneous material using bricks, blocks, and others, including the traditional stone. Composite structures are those involving multiple dissimilar materials. Bamboo is a traditional building material throughout the world tropical and sub-tropical regions. Rammed earth can be considered to be included in masonry construction, but it is a structure very much used in developing countries and it is finding new interest in developed ones ( [[#Cabeza--2021|Cabeza et al. 2021]] ).

The literature evaluating the embodied energy in building materials is extensive, but that considering embodied carbon is much more scarce ( [[#Cabeza--2021|Cabeza et al. 2021]] ). Recently this evaluation is done using the methodology lifecycle assessment (LCA), but since the boundaries used in those studies are different, varying, for example, in the consideration of cradle to grave, cradle to gate, or cradle to cradle, the comparison is very difficult ( [[#Moncaster--2019|Moncaster et al. 2019]] ). A summary of the embodied energy and embodied carbon cradle to gate coefficients reported in the literature are found in Figure 9.9 ( [[#Alcorn--1998|Alcorn and Wood 1998]] ; [[#Crawford--2010|Crawford and Treolar 2010]] ; [[#Vukotic--2010|Vukotic et al. 2010]] ; [[#Symons--2011|Symons 2011]] ; [[#Moncaster--2012|Moncaster and Song 2012]] ; [[#Cabeza--2013|Cabeza et al. 2013]] ; [[#De%20Wolf--2016|De Wolf et al. 2016]] ; [[#Birgisdottir--2017|Birgisdottir et al. 2017]] ; [[#Pomponi--2016|Pomponi and Moncaster 2016]] , 2018; [[#Omrany--2020|Omrany et al. 2020]] ; [[#Cabeza--2021|Cabeza et al. 2021]] ). Steel represents the materials with higher embodied energy, 32–35 MJ kg –1 ; embodied energy in masonry is higher than in concrete and earth materials, but surprisingly, some types of wood have more embodied energy than expected; there are dispersion values in the literature depending on the material. On the other hand, earth materials and wood have the lowest embodied carbon, with less than 0.01 kgCO 2 per kg of material ( [[#Cabeza--2021|Cabeza et al. 2021]] ). The concept of buildings as carbon sinks arise from the idea that wood stores considerable quantities of carbon with a relatively small ratio of carbon emissions to material volume and concrete has substantial embodied carbon emissions with minimal carbon storage capacity ( [[#Sanjuán--2019|Sanjuán et al. 2019]] ; [[#Churkina--2020|Churkina et al. 2020]] ).

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[[File:5dd3ecad963e07fff5d2f6aad9092f41 IPCC_AR6_WGIII_Figure_9_9.png]]

'''Figure 9.9 | Building materials (a) embodied energy and (b) embodied carbon.''' Source: [[#Cabeza--2021|Cabeza et al. (2021)]] .

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