The Designer’s Compass - Part 1: The Carbon Equation: Decoding LCA and Tackling Plastic’s Waste Crisis

Materials serve as a central starting point for modern product design. Designers increasingly use materials as a vehicle for storytelling and a way to define user experiences. These stories focus on sustainability against a rapidly accelerating trajectory in global production. Materials offer one of the main ways designers influence product development toward reduced environmental impact. Understanding materials is challenging because they constantly evolve, lacking a clear target or endpoint.

Sustainability combined with materials often feels like a Wild West—a new frontier demanding adaptation and continuous learning. Designers often feel timid about material choices because they fear making claims that might not yield a positive contribution. Sustainability never simplifies down to choosing one material over another. Designers must instead take a position on the approach best suited for a specific product and industry. This requires planning for optimal lifespan and expected waste streams to maximize recovery. Navigating these twists and turns leads to successful sustainable material selection.

Measuring Environmental Impact: The LCA Framework

Designers need clear, accessible information regarding the environmental impact of materials. Fortunately, a framework for assessing this impact is emerging, driven by consumer expectations and new legislation in key markets like the European Union (EU). Material suppliers face increasing expectations to measure their environmental impact and make results publicly available. They typically provide these results as a cradle-to-gate partial life-cycle analysis (LCA).

A cradle-to-gate study covers every step of manufacturing up to the point where the material leaves the factory gates. This includes the extraction and refinement of raw materials. A full LCA study covers a product’s entire life cycle, from raw materials and manufacturing through disposal. Other terms often used by suppliers include life-cycle inventory (LCI) and environmental product declaration (EPD).

LCA data provided by suppliers, trade organizations, and other sources inform material evaluations. Designers benefit from a basic understanding of the LCA model when seeking environmental information. It is essential to recognize these numbers function as indications rather than absolute facts. LCAs are not always performed uniformly, making accurate comparisons between different studies difficult without expert knowledge. The European Commission launched the Product Environmental Footprint (PEF) methodology. The PEF is expected to become mandatory in the EU in 2024. This new standard will make interpreting and comparing LCA results significantly easier.

Designers should focus their work on problem areas where they can truly reduce environmental impact. Designers must look both at individual materials and the bigger picture. For example, plastics currently face more of a waste problem than an emissions problem. Conversely, metals currently present a larger emissions problem than a waste problem. Considering the entire picture helps designers narrow their focus toward decisions that yield a real difference. Designers should urge suppliers to provide environmental data about specific material grades they consider using.

The Carbon Equation: Energy and Emissions

Calculating greenhouse gas (GHG) emissions and their impact on global warming represents one of the most useful and widely accepted outcomes of LCA studies. Carbon dioxide (CO2) is not the only GHG, but its sheer volume in materials manufacturing makes it critically important. Understanding the role of carbon requires a closer look at the natural carbon cycle. This fundamental natural process is necessary for life on Earth.

The carbon cycle consists of two components: the fast and the slow carbon cycle. The fast carbon cycle connects all life in real time. Plants absorb CO2 and release oxygen. Animals breathe in oxygen and breathe out CO2. The slow carbon cycle relies on chemical and tectonic processes. These processes fossilize organic materials and sequester carbon underground and in the ocean floor over hundreds of millions of years.

Extracting and burning large volumes of this sequestered carbon—as oil, natural gas, or coal—to generate energy upsets the fast carbon cycle. This action releases more CO2 into the atmosphere than plants on Earth can absorb. CO2 traps heat in the atmosphere, slowly warming the planet. If insufficient plants exist to absorb this CO2, it remains in the atmosphere indefinitely.

The materials industry connects to CO2 and global warming in three main ways. First, most CO2 emissions from materials production originate from the energy derived from fossil fuels (coal, natural gas) used in manufacturing. Materials production often requires significant energy. Second, carbon acts as a fundamental building block in many materials. For example, a tree typically consists of 50 percent carbon, while plastics are about 80 percent carbon. Incinerating these materials releases this embodied carbon into the atmosphere as CO2. Third, overuse of biomass-derived materials, such as trees and plants, can cause deforestation. This deforestation reduces the global capacity for absorbing atmospheric CO2.

Global warming potential (GWP) measures how much heat different GHGs trap in the atmosphere, using CO2 as a benchmark. GWP allows all GHG emissions to be consolidated into a single number, expressed as CO2 equivalents (CO2e). GHG emissions for materials in the sources are listed as GWP in units of kilo of CO2e per kilo of material. Designers must exercise caution when comparing GWP numbers. Material density significantly affects comparison results. Steel density, for instance, is about three times that of aluminum. Comparing emissions must therefore rely on the weight of a specific part, not simply kilo for kilo. GHG emissions represent a major environmental challenge, but they are not the only one. Other pressing issues include resource over-exploitation, toxic ingredients, by-products, and the growing waste mountain.

Plastics: The Waste Crisis

Plastics embody the complexity of sustainability. They are extremely useful but rely heavily on non-renewable resources. The world saw an explosive growth in plastic products since mass production began in the early 1900s. This growth resulted in an explosive growth in plastic waste. The OECD’s 2022 Global Plastic Outlook reported that 460 million tonnes of plastic were produced in 2019. Production is expected to reach 1,230 million tonnes by 2060. This forecast paints a bleak picture given the current inability to manage plastic waste.

The plastics industry represented about 1 percent of global CO2 emissions in 2014. That figure is expected to reach 15 percent by 2050. These figures point toward two strategic avenues for addressing plastics’ environmental impact. Strategies must prioritize improved recycling to tackle the waste problem. They must also focus on renewable raw materials to address the increasing emissions problem.

Most plastics used today derive from petrochemicals, specifically refined crude oil or natural gas. These raw materials undergo processing to extract monomers, the molecular building blocks of plastics. Polymerization, a chain reaction, converts these monomers into long chains of molecules, forming a polymer or plastic. The complexity of these processes directly impacts the energy intensity and resulting emissions of plastics production. Plastics requiring fewer manufacturing steps generate fewer emissions and use fewer resources.

Nearly all plastic materials fall into two categories: thermoplastics or thermosetting plastics. Thermoplastics represent the larger group. They are usually supplied in pellet form for high-volume processes like injection molding, blow molding, and extrusion. The forming process is repeatable. Thermoplastics can be recycled by grinding up the waste, reheating it, and forming it into new parts. Conversely, thermosetting plastics (thermosets) are typically liquid resins set or cured by a catalyst such as heat or a chemical reaction. Once thermoset resins form, they cannot be reheated and reprocessed, meaning they are not easily recycled via thermoplastic processes.

The Difficulties of Plastic Recycling

Recycled plastics offer clear environmental benefits. Recycling uses less energy and results in fewer emissions than producing virgin materials. It also keeps plastic waste out of landfills, incinerators, and the environment. However, mechanical recycling, the most common process today, faces significant challenges.

The very properties that made plastics successful often cause recycling problems. The low cost of commodity plastics negatively impacts recycling. The cost of recycling plastics often significantly exceeds the cost of making them from virgin raw materials. Thin, lightweight plastic films, while efficient packaging, are flimsy and difficult to collect. Contaminated plastic waste (e.g., from food or chemicals) requires cleaning to a level sufficient for recycling into new materials.

Various incentives exist to address these issues. Proposed EU legislation may require a mandatory recycled material ratio of 30 percent in plastic packaging by 2030. Such initiatives aim to increase recycling rates and make recycled plastics a valuable commodity. Current recycling volumes remain low. Eurostat reported that only 32 percent of plastic waste was recycled in the EU in 2018. The United Nations Environmental Programme (UNEP) estimated that less than 10 percent of all plastic ever produced has been recycled.

The massive number of different plastics in use complicates recycling. High-quality mechanical recycling requires separating specific plastic materials and grades. Failure to sort carefully results in mixed recycled materials with unpredictable and questionable properties. Complex assemblies often combine many different parts made of different plastic types, or plastics combined with other materials. Joining methods like adhesives, thermal bonding, or overmolding make these products extremely difficult to take apart and recycle efficiently.

Additives cause further recycling complications. Re-melting and grinding colored plastic waste results in an unacceptable blend of colors. Recyclers typically add black or dark grey pigment to achieve color consistency. Producing light-colored or transparent recycled plastics demands much more careful, energy-intensive sorting and cleaning. This intensive cleaning increases the environmental footprint and cost of lighter recycled plastics.

Additives like fire retardants contaminate recycled plastic. This contamination can render the material unsuitable or outright banned from sensitive applications, such as food packaging or toys. Closed-loop recycling may be the only workable solution for contaminated plastics, like those used in consumer electronics.

When discussing recycled materials, distinguishing between Post-Industrial Recycled (PIR) factory waste and Post-Consumer Recycled (PCR) waste is crucial. PIR materials are collected from the factory floor and put directly back into production, generally being more straightforward to recycle. PCR waste has been used, recovered from consumers or demolished buildings, and faces greater complexity in sorting and cleaning. Most standards assessing environmental impact differentiate clearly between PIR and PCR materials. Designers should confirm whether recycled plastics are made with PIR or PCR waste.

Designing Plastics for Circularity

Designers can significantly improve recyclability by reducing the number of different plastics in a product. Making an entire product from a single material is preferable whenever possible. Designers should also minimize the number of additives used. Decoration, branding, and details involving secondary finishes (coatings, films, inserts) should be avoided unless they can be recycled alongside the base material without separation.

Many plastics are available in different grades and qualities, allowing complex products to be made from a single material type. Helly Hansen’s Mono Material collection uses only polyethylene terephthalate (PET). PET works for textile fiber, artificial down, and rigid parts like buttons. On Running’s Cloudneo trainer consists of fewer than 10 components. All components derive from the polyamide family, including the textile upper and the soft elastomer sole, streamlining the recycling process. Adhesives must be avoided unless they are chemically compatible with the plastic used. Foamed plastics should utilize gas-assisted foaming instead of chemical foaming agents.

The European Commission’s PolyCE project produced Design for Recycling, Design from Recycling: Practical Guidelines for Designers, an extremely useful resource for circular design in consumer electronics. RecyClass, a plastics industry organization in Europe, develops methods for defining recyclability and the quality of recycled materials, focusing on packaging. Global capacity for plastic recycling is expected to grow substantially due to mandatory recycled content targets in the EU and other markets.

Recycled Plastic Material Profiles

Virgin plastics generally derive from petrochemicals. Recycled plastics offer a reduced environmental footprint compared to these conventional materials. Designers must understand that recycled plastics may differ from virgin materials functionally and aesthetically. They may have fewer colors available and exhibit visual imperfections like flow lines. Design adjustments might include thicker wall sections to compensate for lower performance.

Recycled Polypropylene (PP)

PP is one of the most widely recycled plastics, along with PE and PET. It is sourced from rigid and flexible packaging waste, automotive parts, furniture, and construction waste. Recycled PP accounted for an estimated 5% of total PP demand in Europe in 2018, totaling about 500,000 tonnes.

• GWP Comparison: Virgin petrochemical-based PP has a GWP of 1.6 kg CO2e / kg. Fortum Circo® PCR PP has a GWP of approximately 0.8 kg CO2e / kg.
• Environmental Resistance: PP has good thermal resistance, with a safe service temperature between 90 and 120°C (195–250°F). It resists moisture and some chemicals, but exhibits poor UV resistance.
• Finishing: The majority of recycled PP is available in black or dark grey shades. Lighter colors and translucent grades are less common due to the intense sorting required. PP generally has poor scratch resistance.

Recycled Polyethylene (PE)

PE includes high-density (HDPE) and low-density (LDPE) varieties. It is sourced from flexible and rigid packaging, furniture, and industrial applications. Recycled HDPE accounted for an estimated 14% of total HDPE demand in Europe in 2018, about 700,000 tonnes.

• GWP Comparison: Virgin petrochemical-based HDPE has a GWP of 1.8 kg CO2e / kg. Fortum Circo® PCR HDPE has a GWP of 0.9 kg CO2e / kg.
• Energy and Water Use: Virgin HDPE production uses 79.3 MJ / kg of energy and 105.5 l / kg of water. Fortum Circo® PCR HDPE uses 7.3 l / kg of water.
• Properties: Virgin HDPE provides good rigidity and tensile strength. Recycled PE generally has poor scratch resistance.

Recycled Polyethylene Terephthalate (PET)

PET is attractive for recycling because large quantities of transparent waste are available from bottles. This allows for new transparent products or flexibility in adding pigments. Recycled PET is sourced from drink bottles, packaging trays, and automotive parts.

• GWP Comparison: Virgin petrochemical-based PET has a GWP of 2.2 kg CO2e / kg. Indorama Deja™ PCR PET has a GWP of 1.2 kg CO2e / kg.
• Circularity: Recycled PET accounted for an estimated 26% of the total amount of PET produced in Europe in 2021.
• Finishing: The clarity of PET bottle waste makes producing light-colored and clear recycled PET easier than with other plastic waste streams. PET offers good scratch resistance, making it suitable for polished, glossy surfaces.

Recycled Acrylonitrile Butadiene Styrene (ABS)

ABS is a widely recycled engineering polymer, valued for high performance at a relatively low cost. It is sourced from consumer electronics, appliances, and automotive parts.

• GWP Comparison: Virgin petrochemical-based ABS has a GWP of 3.1 kg CO2e / kg. MBA Polymers PCR ABS has a significantly lower GWP of 0.4 kg CO2e / kg.
• Toxicity: Recycled ABS may contain flame-retardant additives. It releases toxic fumes when heated above 200°C (390°F).
• Usage: The Electrolux Pure D9 Green vacuum cleaner exterior utilizes 70% recycled ABS.

Recycled Polyamide (PA)

PA (nylon) is tough and durable. The high environmental footprint of virgin PA makes the recycled option attractive.

• GWP Comparison: Virgin petrochemical-based PA6 has a GWP of 6.7 kg CO2e / kg. Aquafil ECONYL® PCR PA6 has a GWP of 1.8 kg CO2e / kg.
• Water Use: Virgin PA6 production uses 1,647 l / kg of water. Aquafil ECONYL® PCR PA6 uses 2,550 l / kg of water.
• Properties: Virgin PA has excellent impact strength and stiffness. Recycled PA may contain flame-retardant additives and gives off toxic fumes above 300°C (570°F).

Recycled Polycarbonate (PC)

PC offers optical clarity and is attractive for transparent applications, despite not being widely recycled.

• GWP Comparison: Virgin petrochemical-based PC has a GWP of 3.4 kg CO2e / kg. Covestro Makrolon® QC 50% PCR PC has a GWP of 2.1 kg CO2e / kg.
• Water Use: Virgin petrochemical-based PC production uses a massive 1,535 l / kg of water.
• Toxicity: Bisphenol A (BPA), a key ingredient, has possible links to hormone disruption. PC should be avoided for food- and water-contact applications.

Recycled Thermoplastic Elastomers (TPEs)

TPEs are soft and flexible materials not currently widely recycled. They are often used in overmolded parts, making separation difficult.

• GWP Comparison: Virgin petrochemical-based TPU has a GWP of 4.7 kg CO2e / kg. TRINSEO™ APILON™ ECO PIR TPU has a GWP of 1.8 kg CO2e / kg.
• Circularity: TPE parts should be made easily separable or the entire product should be made from TPE to maximize recycling likelihood.

Recycled Silicone Rubber

Silicone rubber is generally not widely recycled. Some specialist suppliers offer recycled silicone rubber mixed with virgin silicone.

• GWP Comparison: Virgin silicone has a GWP of 7.1 kg CO2e / kg. Recycled silicone has an estimated GWP of 1 kg CO2e / kg.
• Environmental Resistance: Silicone rubber offers exceptional thermal resistance, withstanding temperatures between –50°C and 350°C (–60° to 660°F).
• Aesthetics: The recycled silicone particles are clearly visible, creating a distinctive speckled look.

Recycled Natural Rubber

Natural rubber is fairly widely recycled, often in the form of used tires. Around half of all used rubber tires in Europe are currently recycled.

• GWP Comparison: Virgin natural rubber (vulcanized) has a GWP of 2.5 kg CO2e / kg. PCR natural rubber granulate has a negative GWP of –0.7 kg CO2e / kg.
• Recycling Process: Recycling depends on the process. Grinding creates powder used as a composite filler. Chemical breakdown (devulcanization) yields material with properties like virgin natural rubber.
• Toxicity: Natural rubber and some vulcanization additives can cause serious allergic reactions.

Beyond Recycling: A Look Ahead

The plastics industry is in a creative phase, exploring the technical potential of different recycling processes, including chemical recycling and new hybrid materials. The goal remains keeping as much plastic waste as possible out of the environment. Transparency and traceability are vital, ideally through a digital passport accompanying every material.

Designers must also consider alternatives such as biodegradable materials. Biodegradable means a material will degrade without negative environmental effects. Compostable materials contain nutrients that enrich the soil, acting as fertilizer during composting. Biodegradable products require caution, as they are capable of causing the same problems as other waste until fully broken down, which can take a long time. Organizations like TÜV Austria screen applications to prevent marketing that advocates guilt-free littering. All biodegradable and compostable materials emit greenhouse gases during degradation.

Tackling the plastics crisis requires recognizing that plastics face a waste problem more urgently than an emissions problem. By prioritizing mono-material design and demanding transparent sourcing data, designers can navigate the Wild West of materials toward truly circular outcomes.