Chapter 5
Decarbonizing Conventional Building Materials
Concrete and Cement
Plastics and Polymer Composites
Masonry and Earth-Based Materials

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Plastics and Polymer Composites

Plastics are everywhere, and exist in many grades and even more chemical compositions. While additives optimise the use of plastics in products, they also greatly complicate recycling. Polymers used in buildings as piping or window frames are rarely recycled at their end-of-use.

Figure 5.11 Total plastics production by region, 1980-2060

Plastics production is expected to grow rapidly in Africa, India and the Middle East.

Source: OECD 2022b.

Use of Plastics in Building Construction Is Increasing Rapidly

Use of plastics and polymer composites is projected to more than double by 2060.

Plastics and polymer composites are ubiquitous materials whose use has skyrocketed since the mid-20th century and is projected to more than double by 2060 (OECD 2022b). Plastics are popular due to the low cost and ease of manufacturing. Plastics production occurs around the world but is expected to grow especially rapidly in Africa, India and the Middle East (see Figure 5.11). In the United States of America, buildings and construction accounted for 16 per cent of total plastics use in 2015 (Di et al. 2021). However, this figure does not account for all the plastics used in the interior furnishings and finishes of buildings, which also can pose risks for the health and well-being of inhabitants from material outgassing.

Figure 5.12 End uses of polymers for the buildings and construction industry

Most plastics are used in the building sector for pipes, windows, insulation, lining and coverings.

Note: The figure shows the mostly widely used plastic polymers in the United States of America (left) and Europe (right). PP = polypropylene, LDPE = low-density polyethylene; HDPE = high-density polyethylene, PET = polyethylene terephthalate, PVC = polyvinyl chloride, PS = polystyrene, EPS = expanded polystyrene. Source: Di et al. 2021; Kawecki, Scheeder and Nowack 2018.

In the U.S. construction sector, the most widely used plastic polymer is PVC (polyvinyl chloride or “vinyl,” used mostly for piping and window frames), followed by high-density polyethylene (HDPE, used in building envelopes) (see Figure 5.12 left) (Di et al. 2021). In Europe, most of the plastics used in buildings are for pipes (mostly PVC but also HDPE and polypropylene), followed by windows (PVC), insulation (expanded polystyrene), linings, building textiles and packaging films (see Figure 5.12 right) (Kawecki, Scheeder and Nowack 2018). With a widespread transition to bio-based material composites, the use of polymeric binding agents would increase dramatically. This would require a massive increase in funding for low-carbon polymers that are biocompatible and bio-based.

Figure 5.13 Life-cycle greenhouse gas emissions from the plastics sector, 2015

The majority of plastics-related emissions are generated during resin production.

Note: The figure shows greenhouse gas emissions by plastic type and life cycle stage. The carbon impact is highest during resin production and lowest during landfilling. PP = polypropylene, LDPE = low-density polyethylene; HDPE = high-density polyethylene, PET = polyethylene terephthalate, PVC = polyvinyl chloride, PS = polystyrene, EPS = expanded polystyrene, PUR = polyurethane, PP&A = polyphthalamide. Source: Zheng and Suh 2019.

The Carbon Intensity of Plastics Varies by Type, and Emissions Are Rising

To reduce carbon emissions from plastics requires reducing the growth rate of the sector by half.

Plastics accounted for 3.4 per cent of global greenhouse gas emissions in 2019, and plastics-related emissions are expected to more than double by 2060 (OECD 2022a; OECD 2022b). Around 61 per cent of emissions from plastics are generated during resin production, 30 per cent during conversion processes and 9 per cent during end-of-use processing (see Figure 5.13) (Zheng and Suh 2019). Emissions are lowest during landfilling because plastics do not degrade – and therefore do not contribute to landfill emissions – for many decades. The carbon intensity of plastics varies by type, with the emissions from carbon fibres being four-fold higher than those from the typical resins used (Nicholson et al. 2021).

Large reductions in the carbon impact of plastics are possible through integrated energy, materials, recycling and demand-management strategies to curb life-cycle emissions. One study estimated that to keep plastics-related emissions in 2050 near 2015 levels (thus avoiding the projected four-fold increase) would require major shifts towards bio-based plastics, renewable energy in production, and recycling, as well as reducing the global plastics growth rate from 4 to 2 per cent (Zheng and Suh 2019).

Recycling Rates of Plastics Are Very Low and Are Not Projected to Increase Substantially

Globally, the average plastics recycling rate is only around 9%.

Recycling offers an opportunity to reduce the demand for new petroleum-based plastics. Yet the average end-of-life recycling rate is only 9 per cent (Geyer, Jambeck and Law 2017; OECD 2022a), leaving much room for improvement. Plastics’ low cost, ease of manufacturing and tunability have resulted in a plethora of chemical compositions that pose technological challenges during recycling. These include concerns about the quality of the feedstock (given the thousands of monomers, additives and processing aids used) (Wiesinger, Wang and Hellweg 2021), colour, contamination and degradation of physical properties. Strict regulations for food-grade applications also limit the use of recycled plastics.

Mechanical recycling is the dominant recycling technology for plastics and entails a series of separation steps, followed by melting and reprocessing. Novel ways to complement mechanical recycling include solvent-based recycling (purification), chemical recycling (depolymerisation, solvolysis) and chemical recovery (thermochemical conversion such as pyrolysis, gasification). However, technologies are highly plastic-specific – requiring strict sorting methods – and industrial implementation and economic and ecological evaluations are mostly pending (Thiounn and Smith 2020; Hofmann et al. 2020).


Decarbonizing Plastics and Polymers

Reduce the demand for virgin plastics by increasing recycling and improving collection and sorting


Recycling plastics offers an opportunity to reduce the demand for petroleum-based plastics. However, plastics recycling faces substantial technological and logistical challenges.


Better collection and sorting can be encouraged through both market incentives (such as greater recycled content) and regulatory incentives (such as annual increases in recovery targets).


For windows, collection schemes should focus on the combined recovery of window glass and frame materials (PVC, aluminium, wood) and off-site processing to minimise glass contamination.

Shift from fossil-based to bio-based feedstocks to reduce emissions from plastics


Bioplastics are either bio-based, biodegradable, or both, with a market share of less than 1 per cent in 2021; only around 50 per cent of bioplastics are biodegradable (European Bioplastics 2022).


End-of-life management of bio-based, non-biodegradable plastics is of concern since landfilling or incineration would lead to greenhouse gas emissions, negating any upfront carbon sequestration benefits.


During the transition from fossil-based to bio-based plastics, their combined appearance in recycling streams will further complicate sorting and recycling.


Misunderstandings about the (bio-)degradability of plastics could lead to an increase rather than decrease of plastics in the environment (Albertsson and Hakkarainen 2017), as bio-degradation depends on controlled industrial composting conditions and would not apply to plastic litter in the environment.

Simplify the chemical compositions of plastics to facilitate greater recycling


Today’s plastics are based on more than 10,000 monomers, additives, and processing aids, with nearly a quarter of them of potential concern (Wiesinger, Wang and  Hellweg 2021). Recycling is hindered by the complexity in product compositions and a lack of information on substance properties.


Designing plastics for the circular economy addresses all life-cycle stages, from circular polymer design (Sobkowicz 2021) to sourcing, manufacturing, use and end-of-use (OECD 2021).