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.

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.

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).
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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.
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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).