Resource-intensive construction practices are speeding up the depletion of primary resources such as gravel, sand, steel, wood, and water. Building materials and products come at a staggering environmental cost when the accumulated impacts throughout their lifecycle are considered from extraction and production through construction and the end-of-service phases. The management of materials that aims to keep materials in the loop for longer decreases pressure on our resources, and this essentially means employing materials that provide durability and flexibility of use, and that can be easily disassembled, reconditioned, and re-used at the end of their lifecycle.

Avoiding the disposal of construction materials is a viable way to minimize loss of ecologic and economic value. It also means designing for less material use. Considering an average life expectancy of 40-60 years for a building, the materials and the design decisions we make today will have a decisive impact long into the future. Demand of building materials is also set to increase, with a projected 280 billion square meters of floor area to be built globally by 2060 [1], which in turn makes the case for circularity and decarbonization of the built environment.

Being able to recirculate cementitious materials and steel scrap from construction and demolition waste is another proven strategy that decreases the amount of raw material used by the most impactful industry materials. Albeit less effective, as remanufacturing with recycled aggregates is still an energy and water intensive process.

Biobased materials have clear advantages when it comes to embodied energy and embodied carbon that is lower than any manufactured material. They are circular in that they are produced by agricultural and forestry by-products. In some cases, whenever kept pure and in absence of chemical treatments and additives, they can be safely returnable to the biosphere. The case for biobased materials is even stronger when we look at their performance capabilities: reduced heat transfer, optimum thermal and acoustic insulation properties, moisture control, biodegradability, and carbon absorbing properties. The purer the material, the better. Avoiding composites and keeping dry connections for easy demountability ensure an optimum circularity performance.

Aiming for long-lasting products and ease of maintenance and repair is also paramount. Extending the lifecycle of materials through supply take back schemes or digital databases are a few of the strategies that can be pursued to maintain building materials and products stocks in use. Several technology solutions are available currently for traceability, or to keep track of materials and products during their lifecycle.

A good hierarchy of materials, listed by global warming potential, is represented in the Construction Materials Pyramid. The pyramid is based on the well-known food pyramid and developed digitally by the Centre for Industrialized Architecture (CINARK) at the Royal Danish Academy.

Moving beyond cradle-to-grave and industry-as-usual, we can imagine a near future world where all our materials can be recirculated in a non-toxic manner, for the benefit of humans and the biosphere at large. Cradle to Cradle, or C2C, advocates for a design philosophy whereby design processes are entirely modelled by nature’s processes. In nature, the concept of waste is nonexistent, and outputs of natural cycles are used as inputs for other natural cycles. Keeping manufactured products separated from nature-based materials is of the utmost importance, in order to maximize the circular potential of each of the two distinct nutrient metabolisms. Emulating natural processes means, first and foremost, working with products that are safe, fully circular and responsible, even compostable. This calls for questioning the toxicity levels of materials that are currently used in construction and that impact our health, and that of our ecosystems.

The design concept, initiated by Professor Michael Braungart and architect William McDonough and illustrated in their 2002 bestseller Cradle to Cradle: Remaking the Way We Make Things, has originated a today well-established health certification for materials, the Cradle to Cradle Certified Products Program.

Declare, administered by the International Living Future Institute, is another established material transparency declaration, or “nutrition label” for construction materials and products, being also an important advocacy tool for more responsible material production and industry change.

Circular business models support the industry to find solutions to new manufacturing, construction, de-construction, maintenance, and repair processes. Servitization or the “product as a service” model, is amongst the most established circular business models today. The root of servitization has been outlined by Professor Walter Stahel in The Performance Economy, where he makes the point that focusing on the performance outcomes of a product, rather than on the product itself, leads to a long-term perspective, with retained resource value over time, less material use, optimized maintenance and increased lifespan.

The applications of this model have been explored and successfully implemented by several building product producers on the construction market, ranging from electric fixtures, all the way to façade systems.

[1] Figures by the Global Buildings Performance Network (GBPN).