![Figure 2: Greenhouse gas (GHG) emissions from material production globally in 2020. Source: Eunomia, 2022 [3].](https://prod-files-secure.s3.us-west-2.amazonaws.com/4f448669-d8c9-4e8f-b77d-b6557c736154/c1fdc553-67b3-43a0-9bad-3dad5db28e1e/image2.png)
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Material production globally amounted to 12.7 Gt CO2e in 2020, including the energy used to produce them. This is a quarter (25%) of total 2020 emissions. The main materials produced were iron & steel (7% of global emissions), cement & concrete (6%), plastics (4%) and aluminium (2%), with other various materials making up the other 6% [3]. In the case of the construction industry, materials widely use also include glass and timber. Construction chemicals also play a role.
Figure 2: Greenhouse gas (GHG) emissions from material production globally in 2020. Source: Eunomia, 2022 [3].
In Europe, 10 million tonnes of plastics each year (20% of total plastics consumption) is attributed to the construction sector. Plastic applications in buildings include insulation, piping and window frames [4]. The emissions of plastics vary depending on the product. For example, plastic production accounts for approximately 1.6-1.95 tonnes of CO2 per tonne of polypropylene [5], a type of plastic commonly used in piping [6],[7].
Aside from plastics, there are other chemicals that are used in construction, such as concrete admixtures, glues, coatings, lacquers… among others [8]. Of course, due to the characteristics of the application of these materials, they are used in smaller amounts than the other materials presented.
After steel, aluminium is the most common metal used for construction purposes, being extensively employed in various sectors ranging from commercial buildings to residential homes. The construction industry in the UK utilizes 40% of the annual production of aluminium. It is used in windows, roofing, cladding, curtain walling and structural glazing, prefabricated buildings, piping, shop fitting and partitions. Aluminium is also used extensively in ladders and scaffolding during the construction phase [9]. However, aluminium is also a carbon-intensive product, with primary aluminium emitting on average 16.5 tonnes of CO2 per tonne of metal [10].
Glass has been conventionally employed as window panes in the construction industry. However, over the past 25 years, there has been a growing trend of using glass as a primary building material. The embodied carbon of glass is mostly associated with the high temperatures needed to produce it. To contextualize it, the value (in MJ/kg) is higher than the embodied carbon of reinforced concrete, and less than the embodied carbon of steel [11]. The emissions of glass production amount to 0.46 tonnes of CO2 per tonne of glass produced [12].
Wood has been used as a construction material for centuries, and engineered timber has gained traction as a building material in the past years. When sourced and harvested responsibly, observing sustainable forest managing strategies, it can be a renewable material [13].
With the increase of energy efficiency measures for buildings, consumption of insulation materials is bound to increase as well. The most common types of materials used for insulation include cellulose, fiberglass, mineral wool (from rock or slag), polyurethane foams and polystyrene [14], [15].