Circular Economy in Architecture

Construction waste refers to materials generated throughout the entire process of a building’s materialization and useful life. This encompasses the extraction and production of materials, construction, and dismantling at the end of its life cycle, including any subsequent renovations carried out.

Due to their volume, construction and demolition waste (CDW) represent the highest percentage of waste in the European Union, accounting for up to one-third of the total waste generated on the continent.

Proper construction waste management not only provides environmental benefits but also generates opportunities for material recovery and reuse, promoting a circular economy in architecture.

Addressing the construction process by considering the entire life cycle of a material or system—with a view toward its subsequent dismantling or reuse—is key to promoting a high-quality material recycling policy that guarantees reuse.

Introduction to linear and circular economies

The problems of the linear economy

A large part of the current problem in waste management stems from the established linear economy model, in which a product is produced, used, and discarded at the end of its useful life without considering the environmental consequences of the waste.

This is a conception based on pure capitalism, where profit is measured solely by the economic result of the productive activity, without considering the impact on people and the environment.

A company creates a product, places it in the free market, and ceases to be responsible for it beyond the mandatory two-year repair warranty. This is an unsustainable cycle undoubtedly destined for failure on a planet with limited resources and a fragile environmental balance constantly altered by human activity.

While there are pathways for recycling or reuse, the lack of regulation and tax rates regarding the ability to separate, reuse, or recycle a product leaves the viability of these processes in the hands of private companies, whose economic and environmental costs are often too high to be profitable.

In fact, less than half of the waste generated worldwide each year is successfully recycled. Studies conclude that of the 60 billion tons of raw materials extracted annually worldwide, half will not be regenerated and will become waste that ends up in landfills, seas, or incinerators—with the associated environmental cost. This waste already totals 2 billion tons generated each year.

It is estimated that by 2050, global consumption will be equivalent to that of three planets, and demand is even expected to increase for materials such as biomass, fossil fuels, metals, and minerals. If we continue at this rate, annual waste generation will increase by 70% between now and 2050.

What is the circular economy?

The circular economy is an economic concept in which products, materials, and resources are kept in circulation for as long as possible.

This constant circulation eliminates the extraction of new raw materials and reduces or minimizes waste generation, turning the process into a closed and sustainable system.

The circular economy prioritizes the production of services over the economy of products. If we add the option to repair or upgrade a product, the need to buy a new one disappears, and the manufacturing company itself can offer the repair or recovery service.

This can only be achieved if we eliminate competition between companies and move toward generating cooperative associations or clusters where raw material production and waste recovery are planned jointly. In this way, a company committed to a circular economy by eliminating waste generation does not lose competitiveness or sell a more expensive product compared to a company that does not implement sustainable management processes.

The concept of the circular economy is not attributed to a single author or date; rather, it is a concept that various associations and thought leaders have coined to propose viable alternatives to obsolete production processes.

One of these is the architect and economist Walter Stahel, who, in 1976, outlined the vision of a ‘loop economy’ and its impact on job creation, economic competitiveness, resource savings, and waste prevention. He is credited with inventing the expression “Cradle to Cradle” in the late 1970s.

Stahel mentions that the circular economy should be considered a generic concept revolving around a set of basic principles. He refers to four main objectives: product life extension, long-life goods, reconditioning activities, and waste prevention.

In architecture, the Cradle to Cradle concept was extensively developed by fellow architect William McDonough, who has spent over 20 years disseminating and proposing solutions to improve the way we build and inhabit, reducing our impact and maintaining a constant circle of resource generation and recovery.

Regarding associations promoting the concept, one of the most relevant international bodies is the NESI Forum, the first Global Forum on New Economy and Social Innovation. The NESI Forum is dedicated not only to raising awareness and disseminating the principles of the circular economy across all sectors but has also created a collaborative platform for users worldwide to propose projects.

Some of the most prominent include a network of municipalities committed to changing the economic model and various projects surrounding food sovereignty, sustainable fashion, and the energy of the future, all through attention to issues such as diversity and female empowerment.

In Spain, we find the Circular Economy Foundation (FEC), which is primarily dedicated to research, dissemination, and training.

EU Regulatory Framework

Considering that half of total greenhouse gas (GHG) emissions and more than 90% of biodiversity loss and water stress are due to resource extraction and processing, the European Green Deal—the roadmap to provide the European Union with a sustainable economy—initiated a strategy with the goal of achieving climate neutrality by 2050.

To fulfill this aspiration, the EU aims to accelerate the transition to a regenerative growth model that gives back to the planet more than it takes, move toward maintaining resource consumption within planetary boundaries, and strive to reduce its consumption footprint while doubling the circular material use rate in the next decade.

To achieve all this, it has generated a regulatory framework by establishing the new Circular Economy Action Plan, which constitutes one of the main building blocks of the European Green Deal, the new European agenda for sustainable growth.

The new Action Plan announces initiatives throughout the entire life cycle of products, aimed, for example, at their design, promoting circular economy processes, fostering sustainable consumption, and ensuring that the resources used are kept in the EU economy for as long as possible. It introduces both legislative and non-legislative measures aimed at areas where action at the EU level provides real added value.

Some of the most prominent objectives include: making sustainable products the norm in the EU; empowering consumers and public buyers; focusing on sectors that use the most resources and where the potential for circularity is high (such as electronics and ICT, batteries and vehicles, packaging, plastics, textiles, construction and buildings, food, water, and nutrients); ensuring less waste; making circularity work for people, regions, and cities; and leading global efforts on the circular economy.[1]

Focusing more specifically on the circular economy in architecture, as early as 2016, the European Commission established an EU Construction and Demolition Waste Management Protocol, identifying that one of the greatest difficulties in recycling this demolition waste is the lack of confidence in the quality of the resulting materials. This lack of confidence reduces the demand for recycled construction materials and hinders the development of construction and demolition waste management and recycling infrastructure in the EU.

The proposed measures will contribute to achieving the Waste Framework Directive’s goal of recycling 70% of construction and demolition waste by 2020, thereby closing the product life cycle by increasing recycling and reuse.[2]

The circular economy in our country: Regulatory framework and its application in the construction sector

Regulatory framework regarding the circular economy in Spain

In Spain, the regulatory framework is established by the Official State Gazette through a Royal Decree regulating the production and management of construction and demolition waste, proposing specific regulations for the waste stream based on producer responsibility.[3]

Among the obligations imposed on the producer, the inclusion of a construction and demolition waste management study in the construction project stands out. This study must include an estimate of the quantity produced, the generic prevention measures to be adopted, the intended destination for the waste, and an assessment of the costs derived from its management.

As a special prevention measure, the obligation is established to conduct an inventory of any hazardous waste generated, proceed with its selective removal, and deliver it to authorized hazardous waste managers.

The treatment of both inert and hazardous waste can only be carried out through so-called mobile plants at fixed recovery or disposal centers, or through disposal in a landfill. In fact, the landfilling of hazardous waste that has not undergone some form of prior treatment is prohibited.

Furthermore, it dictates that the reuse of inert waste from demolitions for construction be considered a recovery operation, thereby encouraging the use of these new recycled materials.

Spanish Circular Economy Strategy 2030

In June 2020, the Council of Ministers approved the Spanish Circular Economy Strategy (EEEC) 2030, which sets out a series of objectives for the target date in its title.

The most prominent are a 30% reduction in national material consumption and a 15% reduction in waste generation, using 2010 as a reference year.

Additionally, it proposes reducing food waste throughout the food chain: 50% at the household level and 20% in production and supply chains starting from 2020.

Finally, it proposes a 10% increase in the reuse of generated municipal waste, which is closely related to the application of the circular economy in architecture, as well as a 10% improvement in water use efficiency and a reduction in greenhouse gas emissions to below 10 million tons of CO₂ equivalent.[4]

Spanish Association of Demolition, Decontamination, Cutting, and Drilling

Specifically in the construction sector, Spain has several associations beginning to implement processes related to the circular economy, such as AEDED (Spanish Association of Demolition, Decontamination, Cutting, and Drilling). In recent years, AEDED has proposed adding a new figure to the flow of actors involved in a production process: the CDW manager. Their role consists of reusing or recovering materials from demolitions. The difference between them is that reusing involves maintaining the material’s original function in another project, while recovering consists of using the waste for any other useful purpose.[5]

The average production of CDW in Spain during the 2011-2015 period was 18.8 million tons, or 0.405 tons/inhabitant/year. These recovery values are on the rise, representing half the CDW production generated prior to 2008.[6]

Green Building Council Spain and the circular economy

The Green Building Council Spain (GBCe) was established in 2009 as a meeting and dialogue platform associated with the international World Green Building Council network.

It works on the implementation of the so-called VERDE Certification, an added value in property transactions that evaluates indoor environmental quality (air, light, noise, comfort), resource management (energy, water, materials), social integration (accessibility, training, communication), and the technical quality (monitoring, documentation, maintenance) of a building.

Furthermore, it has created a database called the Materials Platform, which provides transparent information regarding environmental impact through Environmental Product Declarations (EPD), which analyze the life cycle of products and their carbon emissions.

Another interesting resource is its publications, some of a more informative nature referring to social values in urban interventions and others highly technical, such as the Report on Indicators for Measuring Circularity in the Construction Sector.

This is a pioneering proposal that provides a comprehensive analysis of a building’s life cycle through short- and long-term indicators corresponding to the construction phase and the building’s useful life. It specifies the calculation criteria and details extensively while drawing on existing sources of indicators with data on building and the circular economy, applying the principle of cooperation advocated by this new economic model.[7]

References for circular economy in architecture

William McDonough and the “Cradle to Cradle” concept

One of the most relevant names when discussing the circular economy in architecture is William McDonough, an American architect who has spent over 20 years promoting the implementation of the “Cradle to Cradle” concept (circular production economy), which replaces the current “Cradle to Grave” model referring to production processes with a beginning and an end. In 2002, McDonough co-authored the book Cradle to Cradle: Remaking the Way We Make Things with chemist Michael Braungart.

McDonough is an architect who has dedicated his life to this concept, proposing to change the end of the game for an infinite game.[8]

This is a philosophy conceived in the 1970s that can be applied at any scale, from macroeconomics to molecular structures.

McDonough challenges the end consumer and their responsibility, asking them to change the dynamics and habits in which they have been educated—always needing new things. Getting the most out of products is possible, profitable, and necessary.

Furthermore, he proposes pursuing a simple goal: a world that is exquisitely diverse, safe, healthy, and just, with clean air, clean water, and energy, enjoyed economically, equitably, ecologically, and elegantly.

This same architect and writer is a pioneer in applying the circular economy to architecture, having designed many sustainable architectural projects and created a program to disseminate these ideas, such as the Adam Joseph Lewis Center for Environmental Studies at Oberlin College or the NASA Sustainability Base.

McDonough refers to what he calls two metabolisms—biological and technical—which distinguish two types of products.

Examples of real-world application of the circular economy in architecture

The construction sector is one of the key sectors in global energy transformation and resource management.

The circular economy will play an important role as a strategy to articulate the change in model. Consequently, the European community is working under increasing regulatory pressure, demanding a series of changes that respond to the new model, such as nearly zero-energy buildings where life cycle analysis goes beyond the mere calculation of the carbon footprint.

Basically, the circular economy in architecture emphasizes three concepts: durability, repairability, and separability, all with the goal of slowing down the cycle as much as possible. Thus, we are moving toward simpler construction models, as complexity results in components that cannot be repaired or improved.

The use of materials following circular economy principles involves research into new construction materials, but also reuse through the dismantling of structures whose materials are reused directly or after undergoing a transformation process with minimal ecological impact. The goal is to eliminate and reduce the use of materials that consume non-renewable resources, are not recyclable, or require a large amount of energy to be extracted, shaped, recovered, or recycled.

Below, we review some examples of projects where strategies based on the circular economy in architecture have been applied.

Companies applying circular economy in architecture

Recycling textile waste for thermal insulation

The textile sector is traditionally a sector with a high ecological footprint and an immense impact in terms of waste.

In the European Union, textile waste is around 16 million tons annually, of which only about 15 to 20% is recycled or recovered. While much work remains in terms of awareness and textile waste reduction, the first viable initiatives for utilizing textile waste as thermal insulation are already appearing in the construction sector.

One example is the Basque cooperative Koopera, which, in collaboration with companies specialized in construction and the manufacture of non-woven materials, has led a circular economy project that converts textile waste into insulation panels for construction. In this way, it is estimated that a total of 600 tons of post-consumer cotton can be recovered over five years to be converted into 200,000 m² of panels.[8]

This is a pioneering national project that has revalued a material, achieving excellent results in acoustic and thermal behavior while complementing it with very competitive economic performance in the market. Thus, a material developed under the principles of the circular economy in architecture is obtained, with the consequent added value for sustainable construction at the same cost as non-recycled products.

If you would like more information on textile waste recycling in national companies, we recommend reading this post on the Vivir Sin Plástico blog.

Automated technology to reuse used bricks

Perhaps one of the most basic and simple ideas in applying the circular economy to architecture is the reuse of materials after a building’s useful life. This is already applied to products that reach an appropriate value in reuse—such as steel or other metals present in construction—but it is not as common in ceramic materials like bricks.

Brick is a traditional construction material whose main ecological impact stems from a transformation process involving firing at high temperatures, which requires high energy demand. In Spain, a country where clayey soils abound and there is little tradition of timber construction due to the scarcity of raw materials, ceramic pieces have traditionally been used as a versatile construction material for both structural systems and finishes.

Bricks can easily last for several centuries, but those discarded as a result of demolition usually contain cement or concrete residues. The difficulty of utilizing them turns them into unusable waste that ends up in landfills or, at best, is used as aggregate material for road construction or sub-bases.

The European project Rebrick has developed and tested a novel system that automatically sorts waste generated in a demolition, separating reusable bricks.

This technology was designed and patented by the Danish company Gamle Mursten and consists of a mechanical system that automatically cleans concrete and cement from old bricks. Therefore, the bricks can be reused for construction activities.

This process involves reducing the significant environmental impact of brick manufacturing since we notably increase their useful life—each reused brick will save 0.5 kg of CO₂ compared to building with new bricks.[9]

This is undoubtedly an innovation to consider that must be replicated to be viable. We must not forget that in the case of reusing materials extracted from a dismantled building, one of the main aspects to consider is their use in projects near the extraction site to avoid increasing the product’s ecological footprint through CO₂ emitted during transport.

Philips moves from selling luminaires to selling light

The company Philips has launched a new line of business that represents a 180-degree turn for its flagship product, moving from selling luminaires to offering a lighting service.

In this way, Philips moves from manufacturing and selling luminaires, bulbs, wiring, and detectors to selling a lighting service to the consumer. By placing the user at the center, it analyzes and simplifies their needs into a basic requirement: having a well-lit space, in the most abstract sense of the word.

Since all elements of the installation remain their property, we are talking about an infrastructure lease, and the maintenance of the product becomes the responsibility of the supplier. Consequently, the supplier becomes the party most interested in extending the products’ useful life and minimizing their energy consumption, as well as allowing for their recovery and repair process to reduce maintenance costs. All this while adjusting costs to compete in an emerging light rental market.

This is the opposite of the situation we are used to, where companies move from having an interest in their products having an expiration date or even planned obsolescence to having an interest in them lasting as long as possible, being recoverable, and being repairable to be put back into circulation at the end of their useful life.

This is a very interesting case study, as it is capable of being implemented in all companies that are traditionally manufacturers of a product.

Architectural projects applying the circular economy

Venlo City Hall, Netherlands

The Netherlands has the highest recycling and recirculation rates in Europe. A few years ago, the Venlo City Hall organized a competition won by the Kraaijvanger Architects team.

The competition did not propose conventional criteria for program and area, but rather design and construction strategies to adopt circularity measures. That is, contestants had to specify which work systems, processes, and certifications they would use to carry out the project design. Based on this, an architectural firm and a construction company were chosen.

Kraaijvanger Architects prioritized air purification through plant filters, water management through consumption reduction and recirculation, the use of demountable and reversible joints, and Cradle to Cradle certified materials.

Regarding the air systems, the building operates via a solar chimney, circulating air by convection thanks to the sun’s energy and utilizing the thermal mass of its basements to temper it in both winter and summer. This is a passive ventilation system that saves a large amount of machinery normally used for mechanical ventilation.

Additionally, it passes air through plant screens to clean it, thanks to what is considered the largest green facade in Europe (with a surface area of 2,200 m²). This allows for the absorption of suspended particles and nitrogen oxides, an effect that the firm has demonstrated numerically through quantification studies based on different species.

It has also been shown that such a green surface not only affects the quality of the indoor environment but directly influences the air in the building’s surroundings up to 500 m away.

In addition to all these strategies, there is a desire for dissemination—making a showcase of possibilities visible on the exterior skin, divided into the two concepts mentioned by McDonough: technical and biological nutrition. Thus, the green facade facing north refers to the biospheric cycle and the south to the technological cycle, where solar collectors, shading, and light reflectors are located.

The building’s energy is generated through a combined geothermal and aerothermal system, both operating via solar power supply.

The water management system starts from the premise that the average water consumption per person per day is 127 liters, but only 4.5 of these are potable water. Therefore, it creates a system with five different networks, starting with potable water and rainwater harvesting. Once used, these two are filtered with vegetation and reused in the greywater network for toilets. The toilet network, in turn, branches into yellow water and black water.

Natural materials are used, such as cross-laminated timber without adhesives and concrete without additives. Regarding the reversibility of joints to reuse raw materials, the strategy consists of minimizing chemical joints and prioritizing dry ones. Thus, the project was again used to drive research, leading a company to develop a reversible adhesive that allowed for the removal of ceramic flooring—a new concept, a reversible chemical joint.

At an economic level, the city council did not calculate the construction cost compared to a conventional building—which represented a variation of about 3 million euros—but instead focused on long-term thinking and valued the investment over a 40-year period. Not only the construction cost was considered, but also the operating costs (maintenance and energy and resource consumption), calculating a total saving over the 40-year forecast of 17 million euros—an 11% return on the initial investment thanks to the application of circular economy concepts in architecture.[10]

Leitat Headquarters Barcelona

Another interesting building to analyze in the application of the circular economy in architecture is the Leitat Headquarters, an environmental management agency in the Poblenou neighborhood of Barcelona, which follows a layered building scheme.
The proposal of this project is to divide a property into different layers to allow for a direct impact on the building’s durability, as each layer will be capable of working with a different time horizon, unlike conventional buildings.

As a building with a program for technological testing, it requires high flexibility of installations and the possibility of highly variable partitioning over time. Thus, the Leitat Headquarters applies the layer theory as a strategy to untangle the building’s complexity.

The structure is designed using two frames that act as facades as the only contact with the ground, so there is no interior partitioning limiting the design. From there, an envelope and the installation layer are added, which run along the exterior to avoid courtyards and ducts.

Finally, the outermost layer is the finish, which provides the desired image for the property.

For all these reasons, this building is a good example of how it is sometimes not necessary to use high technology or extraordinary materials to achieve a high level of circularity. In some cases, a well-executed typological approach allows us to greatly extend durability, reduce construction and material costs through high prefabrication, minimize maintenance, make uses flexible so it never falls into abandonment, and limit expenses on coatings, among others.

Evidence of this is its multiple energy certifications—Energy Certification A and Green 4-leaf environmental certification from the Green Building Council—its low energy consumption—226 kWh/m² per year—and low CO₂ emissions—50 kg CO₂/m².