Carbon content

Carbon content has a number of slightly differing meanings in different situations:

• Energy: In energy generation, carbon content can mean the carbon dioxide equivalent (or C02e) that is released through the associated or actual combustion or oxidation of a fossil fuel, used to generate electricity. Also referred to as carbon intensity.
• Materials: In the assessment of biogenic, natural and geological materials, carbon content can refer to the amount of carbon that has been sequestered in a material over its lifespan or in existence. For example in timber, an average figure might be that carbon makes up about 50% of the dry mass of a tree or in comparison calcite which is comprised of about 12% carbon (note the density of timber might be around 0.90 g/cm3 whilst calcite is around 2.71 g/cm3). The carbon content of soil is also a significant aspect of interpretation, where normal top-soils might contain from 0.5% to 3.0% organic carbon, peat soils can contain up to 52% carbon by dry weight (Lindsay, 2010). As with timber and calcite it is also important to consider the density of these soils when making comparisons, in that a topsoil might range from 0.5 g/cm3 to 2.2 g /cm3, and tropical peat soils might be in the region of 1.4 g/cm3.
• Products: In the assessment of the environmental performance of products, carbon content can refer to the amount of carbon ( or carbon equivalent ) that is associated with a material on a whole life basis. Depending on the assessment method this will include extraction, processing, installation and potentially end of life scenarios. For example the the ICE carbon database refers to the embodied carbon footprint as the amount of carbon (CO2 or CO2e emission) to produce a material. and differentiates in assessments from cradle to (factory) gate, cradle to site (of use), or cradle to grave (end of life).
• Metals: In the evaluation of metals, in particular steel, carbon content is used to describe the different types, which relate to strength. Low-carbon or mild steels consists of less than 0.30% carbon and are likely to be relatively low grade flexible rolled sheet materials. Medium-carbon steel consists of 0.30% to 0.60% carbon and are likely to be used for axles, gears, shafts, couplings or forgings. High-carbon steel contain more than 0.60% carbon, they are the strongest type, used for durable cutting tools, masonry nails etc. As the carbon content of steel increases, it becomes stronger and harder but also more susceptible to rust and corrosion as well as being more difficult to work with.

[edit] Related articles on Designing Buildings

• Calcination
• Calcite
• Types of metal.
• Types of steel.
• Types of timber.
• Types of soil.
• Vickers hardness rating scale.
• Whole life carbon assessment of timber.
• Wood, embodied carbon and operational carbon.

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