Product design and business models have a crucial role to play in the pivot toward a circular economy, reducing waste, and preserving valuable materials. This can only occur with a responsible attitude toward material consumption, and it all begins at the design phase.
While the move from linear to circular models is a complex undertaking, including both product development and business model design, the benefits are massive for the environment, society, and business.
Implementing circular design principles at the early stage of the product design process is important because the possibility of implementing changes to already established supply chains, processes, and equipment is cumbersome. This article explores the principles of circular design and introduces design strategies helping to slow and close material loops. Let's get started.
Successful products solve a problem for the user. However, the design process should consider more than just end-user needs. Developing products in the modern world must be more expansive and evaluate the system where the designer and user exist.
The linear economy is our traditional model. It is characterized by the "make, use, waste" approach to our resources. Raw materials extracted from the ground are turned into products for the end user, used for a while, and then thrown in a landfill. This process generates waste and pollution and wastes perfectly usable resources.
The linear economy is an issue because it focuses on productivity at the expense of people and the planet. The constant pressure on our water, air, and soil is linked to the destruction of the ecosystems that support life on Earth.  Moreover, excessive reliance on non-renewable natural resources accelerates the point at which they will run out. 
The circular design is an alternative to the traditional model. It reimagines how we design, develop, and use products, including using sustainable materials, extending life cycles, and recycling. 
A decade ago, the Ellen MacArthur Foundation described the circular economy as a business model “that is restorative by intention; aims to rely on renewable energy; minimizes, tracks, and eliminates the use of toxic chemicals; and eradicates waste through careful design.” 
The circular mindset is about more than just recycling. It is about designing more long-lasting and adaptable products while collecting waste from the system and turning that into new usable products.
There are two primary areas or approaches within the circular design principles. They are:
Slowing cycles of resource use: Extending products' lifecycle through design for longevity, repair, sharing, etc., and ensuring any extracted materials bring maximum value.
Closing resource loops: Reduce waste and resource use by transforming the end of the product life cycle through design for recycling, upcycling, disassembly, and more. 
Before introducing the different strategies for implementing these principles into your day-to-day operation, let's go through the thinking in a bit more detail.
Principles of circular design
Circular design has two core pillars: slowing and closing resource loops. Both of these considerations must happen at the design stage. Some theorists have suggested that the circular economy must operate like our natural systems or ecologies, where raw materials and matter are recycled and reused constantly. 
Slowing and closing resource loops both serve the purpose of reducing waste but have fundamentally different characteristics. Both approaches are also mutually supportive, but the means are different.
Slowing resource loops
Slowing resource loops refers to the extended and repeated usage of items over an extended duration. By creating products with extended lifespans and implementing strategies like repair and remanufacturing, companies can lengthen the period and intensity of product use, consequently reducing the rate at which resources are consumed.
Closing resource loops
Where slowing resource loops focuses on the use phase of goods, closing resource loops occur after a product's usable life. By means of recycling, the connection between the end-of-use phase and the manufacturing process is bridged, leading to a continuous circulation of resources in a closed-loop system.
Narrowing resource loops
We've been talking about two main principles in circular design, but there's also a third approach that's closely related to the two previously covered strategies. Narrowing resource loops refers to resource efficiency aiming to reduce the total amount of material used per product while achieving similar or even improved performance. This approach has been successfully used in the linear economy, but it can also be used together with circular design principles to enforce their impact.
Although both slowing and narrowing resource flows may lead to similar outcomes (reduced resource flow through the system), they differ in their relationship with time. The goal of resource efficiency is not to create circulating material flows per se but to reduce the total amount of material used in production. Therefore, failing to consider the time dimension may lead to accelerated linear resource consumption (increased sales of more efficient products), yielding minimal net savings in the long run. 
Circular design strategies
While much of the circular design literature centers around what corporate entities can do to reduce the pressure on our resources, design is about human experiences. Designers play a central role in influencing not just product features and aesthetics but also our culture. Sustainable design is about creating new, valuable, eco-friendly products and systems that boost economic competitiveness while promoting sustainable consumption.  Designing for a circular economy offers an opportunity to remove barriers and change attitudes towards more responsible production and consumption, as you can find out from some of the real-life circular economy examples.
Circular design strategies can focus on both circular product design and circular business models. Most often, companies combine both because they are mutually reinforcing and have synergies. Tables 1 and 2 will provide you with an overview of different strategies, distinguished by their primary principle.
Circular product design strategies
Designing circular products focuses on creating high-quality, durable products that make use of the resources already in circulation. In the next section, we will look at strategies that designers can use to create longer-lasting and more sustainable products.
Product design strategies
|Design long-life products||Creating products that are both emotionally and functionally durable.||
|Design for product life extension||Incorporating strategies that promote repairability, standardization, upgradability, and disassembly.||
|Design for recycling||Creating products that can be easily and effectively recycled at the end of their useful life.||
Table 1. Circular product design strategies.
Design for long-life products
Design for emotional attachment and trust: Constantly changing trends and consumer preferences are a rule rather than an exception. Emotional durability is a concept that emphasizes the importance of creating strong emotional connections between consumers and products. The idea is to encourage longer product lifespans by fostering a sense of attachment, satisfaction, and value.
To create products that are liked, loved, and trusted for years and even decades, companies should create products that are visually attractive and timeless. By avoiding short-lived trends or fads, emotionally durable products can maintain their appeal over time.
Personalization can also foster a sense of ownership and attachment. This can be achieved through modular designs, interchangeable components, or offering a range of customization options.
As with functional durability, high-quality materials and craftsmanship can create a perception of value and emotional durability, encouraging consumers to invest in products that they believe will last and provide satisfaction for a longer time. Combining this with storytelling, connecting products with a story of a meaningful origin or the artisans who crafted them, can further strengthen the emotional value and encourage consumers to cherish and preserve the products.
Consider luxury watches, for example. Their timeless design and the stories of their reliability in extreme conditions, from the moon to deep-sea diving, are likely to reinforce the brand image and make the products desirable, despite the premium pricing.
Design for durability: Fast fashion and disposable goods are symbolic of the linear economy. It prioritizes quick, cost-effective production and profits while ignoring this approach's long-term impact.
In circular design, one of the key principles is to build long-lasting products. Designing durable products with a long life cycle means less raw material is extracted from the ground, and fewer products end up in landfills.
Longevity must be a consideration in the design phase. It involves consciously using low-impact materials and production techniques that select for longevity. 
Design for product life extension
Design for ease of maintenance and repair: Repairability is an essential consideration at the design stage. Products must be easy to repair and maintain so that users can extend their lifecycle. Some critical aspects of this principle include making disassembly safe and accessible, ensuring module parts are easy to source, and working towards standardization of components.
One approach is using a modular design. Modularity refers to design thinking that dictates that firms should build products using separate and independent parts. Each product can be disassembled, with each module easily reused, recycled, replaced, and so on.
The overall product lifecycle is unaffected when one part wears out or malfunctions, as it's easily replaceable. Additionally, users can upgrade parts to improve the product, reducing the demand for new goods.
A bicycle is an excellent example of a modular product. Breaks, wheels, chains, and more can be bought and adjusted, meaning the product itself can last for decades.
Design for standardization and compatibility: Standardization is strongly related to the ease of maintenance and repair. It's about creating products with parts that fit other products as well. Standardization offers several benefits helping to keep products in use longer as well as simplifying production and end-of-life management.
Standardizing components and materials allows for easier replacement and repair of parts, as well as promoting modularity and upgradability. This enhances product longevity and reduces waste. Furthermore, standardization and compatibility ensure that different products, parts, or systems can work together seamlessly, making it easier for consumers to adopt and maintain these products.
Standardized products are often designed for easy disassembly, which simplifies end-of-life management, including repair, remanufacturing, and recycling. This helps to minimize waste and supports a closed-loop resource flow.
By adhering to common specifications and guidelines, manufacturers can streamline their production processes, reducing costs and resource use. It can also enable better communication and collaboration between stakeholders, such as designers, manufacturers, regulators, and recyclers, which is required for a faster circular economy adaption.
Design for upgradability and adaptability: Upgradability and adaptability emphasize designing products that can be easily modified, upgraded, or adapted to suit changing requirements, preferences, or technological advancements.
Upgradability refers to a product's ability to maintain its usefulness in the face of evolving circumstances by enhancing its quality, worth, efficacy, or performance. Products designed with upgradability in mind allow components to be replaced or updated without discarding the entire product. This approach not only extends the product's life but also reduces waste and resource consumption.
Adaptability emphasizes designing products that can be easily altered or customized to meet the changing needs or preferences of users. This could involve adjustable features, modular components, or designs that accommodate multiple functions. By providing flexibility and personalization options, adaptable products encourage users to retain them for longer periods, thus reducing the need for frequent replacements and conserving resources.
Design for disassembly: Design for disassembly is a type of design thinking that builds products with their end-of-life cycle in mind. As such, when they reach the point where they can no longer provide value, they can be stripped and used for parts, while the remaining materials are biodegradable or reusable in some other way.
Design for recycling
Where previously presented strategies focus on slowing down the material cycle, design for recycling focuses on creating closed loops where used materials are recycled back into the manufacturing process of new products or into the biological cycle.
Circular thinking emphasizes that products should be designed with the end of life in mind. Design for recycling focuses on creating products and packaging that can be easily and effectively recycled at the end of their useful life. By considering recycling requirements during the design phase, businesses aim to create closed-loop systems where materials are either reused or recycled at the end of their useful life.
The first step is favoring materials that are easily recyclable and avoiding materials that are difficult to recycle or may contaminate recycling streams, such as certain composites or mixed-material products. Moreover, designing products that allow for easy separation of materials is important to facilitate efficient recycling processes. For example, using easily removable fasteners or designing components with clear separation points.
Designers should also aim to use as few materials as possible and select materials that are compatible with the existing recycling infrastructure to simplify the recycling process further and improve recycling rates.
Designing products that can be disassembled also supports recycling efforts. This allows for better separation of components and materials, making recycling more efficient.
Circular business model strategies
Business models represent a way for companies to commercialize their products and services. The prevalent linear economy creates wrong incentives for manufacturers and retailers as it aims to maximize profits through unit sales and cutting costs. However, the growing pressure on businesses to take a more sustainable approach is forcing them to rethink business models to fit the circular economy.
Business model strategies
|Product-as-a-service model||Shifting the focus from selling ownership to providing access through, e.g., rental and subscription models.||
|Extending product value||Prolonging the useful life of products driven by take-back programs and refurbishment.||
|Classic long-life model||Designing, manufacturing, and marketing products with extended lifespans and durability.||
|Encourage sufficiency||Encouraging consumers to buy less but better.||
|Extending resource value||Exploiting the residual value of the materials used in products and converting otherwise discarded resources into new innovative products and materials.||
|Industrial symbiosis||Making use of the byproducts of different processes within a network of multiple stakeholders.||
Table 2. Circular business model strategies.
The Product-as-a-Service (PaaS) model is an approach in business model design that shifts the focus from selling physical products to providing the functionality, performance, or benefits those products offer. Under this model, customers pay for the use of a product or service rather than owning it outright, and the responsibility for the product's lifecycle management lies with the service provider.
This model encourages businesses to design durable, long-lasting, and easily maintainable products, as they remain the property of the service provider and can be reused or refurbished for multiple customers.
The PaaS model contributes to the circular economy in several ways. Since service providers have the incentive to maximize the use of their products, they are more likely to design products that have longer product lifespans. The PaaS model also encourages the efficient use of resources by optimizing product utilization through sharing-based models such as rentals or subscriptions.
The PaaS model can offer customers the benefits of the latest technology and product features without the upfront cost and hassle associated with ownership, such as storing and maintaining the products. This can lead to increased customer satisfaction and loyalty.
Adopting the PaaS model allows businesses to tap into new revenue streams while fostering long-term relationships with customers. Therefore, the model is also likely to increase brand loyalty and customer retention.
Examples of the PaaS model exist in various industries, such as transportation (e.g., bike-sharing, car-sharing), electronics (e.g., smartphone or computer leasing), and appliances (e.g., washing machines or lighting as a service).
Extending product value
Product life extension aims to prolong the useful life of products by emphasizing repair, maintenance, refurbishment, remanufacturing, or upgrading. By focusing on extending the life of products through maintenance and repair services, companies can reduce the need to produce new goods for the market to meet the demand.
At the heart of the strategy is the efficient retrieval of used products from the market, leading to the refurbishment of non-functional products instead of becoming waste. Consistent product returns can be facilitated through take-back programs and partnerships (e.g. with retailers, logistics firms, and collection centers) as part of the value creation and delivery process. After industrial refurbishment and maintenance, products can be sold "as new", creating a whole new market for the company's products.
In the clothing industry, for example, the second-hand market is forecast to exceed $350 billion by 2027 and, by 2032, will already account for twice as much of the total market as fast fashion. 
Besides new revenue streams from second-hand sales, product life extension strategies can help companies to lower overall manufacturing costs. While the operation includes rising labor and logistics costs, the new revenue streams often outweigh the rising costs. In addition, it is up to the company to decide whether to keep the operation in-house or outsource it to a partner. A number of companies have emerged in various industries that offer a branded resell-as-a-service, managing the entire operation from logistics to refurbishment.
At the socio-economic level, product life extension strategies can create new job opportunities in areas such as repair, refurbishment, and remanufacturing, contributing to local economies and promoting the development of specialized skills.
Classic long-life model
The classic long-life model is a business strategy that focuses on designing, manufacturing, and marketing products with extended lifespans, durability, and low maintenance requirements.  This approach aligns with the principles of the circular economy by prioritizing product longevity.
The classic long-life model offers several benefits and implications. By emphasizing long-lasting products, companies invest in research, development, and materials that ensure their products are durable, reliable, and can withstand the test of time.
Longer-lasting products reduce the need for frequent replacements, leading to lower resource consumption and less environmental impact over the product's life cycle. Extending product lifespans helps reduce waste generation, as fewer products are discarded and replaced. This approach also encourages manufacturers to consider end-of-life management strategies, such as repair, refurbishment, and recycling.
Customers who invest in long-life products typically experience greater satisfaction due to the product's durability, reliability, and low maintenance requirements, fostering brand loyalty and positive word of mouth.
This gives companies an opportunity to charge a premium for long-lasting products, as customers perceive them to offer better value for money in the long run due to their extended lifespans and reduced need for repairs or replacements. Providing robust customer support and after-sales services, such as warranties, repairs, and maintenance, can further strengthen customer loyalty. Thus, the classic long-life model can build a strong reputation for sustainability, quality, and durability, setting brands apart from competitors in the market.
While the classic long-life model offers significant benefits, it may also present challenges, such as the need to invest in research and development, higher initial production costs, and potential risks associated with a slower product replacement cycle. However, companies that successfully implement this model can contribute to a more sustainable economy while enhancing customer satisfaction and building a strong brand.
Encouraging sufficiency addresses not only the product's durability and longevity but also the responsible consumption and efficient use of resources. Integrating sufficiency into the classic long-life model further enhances its alignment with the circular economy principles and can yield additional benefits.
A sufficiency-oriented mindset encourages businesses to design and market products that meet genuine customer needs rather than encouraging overconsumption or excessive functionality. Companies adopting a sufficiency approach can educate consumers about the long-term value of their products, responsible consumption practices, and the environmental benefits of choosing durable, long-lasting products over disposable alternatives. 
A classic example of encouraging sufficiency is Patagonia's Don't Buy This Jacket campaign. A sufficiency mindset can also promote collaborative consumption models, such as sharing, renting, or leasing, which can further extend the lifespan of products and optimize their utilization.
Companies can offer incentives, such as discounts or rewards, to customers who choose to repair, upgrade, or maintain their existing products instead of purchasing new ones, thereby encouraging more sustainable consumption patterns. Overall, selling sustainable, high-quality products to customers and providing comprehensive after-sales services fosters brand loyalty and positive word of mouth.
Extending resource value
Extending resource value is also dependent on take-back programs, similar to the product life extension strategy. Therefore, these two strategies have strong synergies. The difference comes from the fact that while the PLE strategy aims to extend the life of products, extending resource value aims to exploit the residual value of the materials used in products and convert otherwise discarded resources into fresh forms of value and new innovative products.
A great example of this approach is Adidas helping consumers to remove plastic waste. By turning ocean plastic into recycled polyester, the company is aiming to switch to recycled polyester wherever possible by 2024.
By capitalizing on the residual value of resources, extending resource value aims to make the product more attractive to customers with environmental concerns while simultaneously cutting material expenses and overall product costs.  Value creation and delivery will involve establishing fresh partnerships and take-back mechanisms to gather and obtain materials.
Industrial symbiosis is built around the idea of closed-loop systems, where the outputs of one process serve as inputs for other processes. It's a process-oriented approach often taking place at the manufacturing level.
This type of activity is not at all uncommon, and many companies make use of the byproducts of different processes internally. However, industrial symbiosis extends this thinking to networks of multiple actors. The aim is to cut costs between all participants and exchange byproducts between participants, which may be valueless to some but valuable to others. 
As industrial symbiosis requires close cooperation between stakeholders, local networks are better placed to create value through this strategy. A simple example is a shared waste sorting and collection point. A more far-reaching example comes from the fuel company Neste, which uses the cooking oil used in restaurants to produce biofuels.
The circular economy can transform how we think about the design and consumption of goods. However, taking the theory into practice requires holistic and thorough planning and evaluation of different approaches. Usually, the best results are achieved through a combination of multiple strategies.
Circular design will reduce the pressure on our existing resources and reduce the number of items destined for landfills. By following the core principles of circular design, slowing and closing material loops, businesses can extend products' usable lives while reducing the need for virgin materials through reuse and recycling. Additionally, business models promoting better utilization of durable goods, such as rentals and subscriptions, can significantly impact the cultural shift toward a more conscious production and consumption.
The green transformation offers a massive business opportunity boosted by regulation and changing consumer preferences. There are always winners and losers in big changes, but generally, those who dare to think innovatively have a better chance to succeed in the long term.
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