Circularity of Building Blocks: The Age of Materials


In the context of Smart Building, energetic efficiency is always discussed and placed on the spotlight... but often referring to the electric grids or infrastructures installed. During the last decades, we have forgotten about another crucial energy element: the composition and capacities of the materials we use for the buildings themselves, and the possibility of reutilizing them.


  • Like we would work with (or rather, against) entropy, dealing with exergy is a design job.
  • Why don’t we try to enhance the Retained Value of buildings?
  • We don’t discuss building sustainability anymore, but building circularity potential 


IGNASI CUBIÑÁPor Ignasi Cubiñá 

Co-Founder and CEO of EconIntelligentGrowth s.l. (EIG), Barcelona. Biologist. Collaborates with WM+P (William McDonough+Partners) on architectural projects in Spain

In the last decade, most of the focus on buildings design and management has been focused on energy management and energy efficiency. The Smart City concept has been carved on the stone of better energy design for buildings, transportation and all kind of devices, aimed to enhance the life quality of citizens while keeping the energy bill as low as possible. This is unarguably a fair objective and a good driver for innovation for both people and companies, but is this enough to serve the ultimate purpose of a Smart City? 


The role of materials: from buildings to cities

Those of us who don’t bear a degree on physics tend to decouple energy from materials. While we know that energy and matter are two sides of the same coin, one of them is inherently governed by the laws of nature and physics. What relates energy and materials is the so-called Exergy efficiency (referred here as the usable energy contained in materials). While thermodynamics tell us that energy can’t be lost in absolute terms, exergy tends to be lost all along the way. Like we would work with (or rather, against) entropy, dealing with exergy is a design job. 


Circular Economy

Circular Economy


Why is Exergy important for Smart buildings? 

Buildings are made out of building blocks, the cells of the metabolism using a faked analogism of living systems. The interaction between them determines the systems and sub-systems that are assembled in whole buildings. When these building blocks – the construction materials – are poorly interconnected and badly designed, the final result is exergy efficiency lost throughout the lifespan of the building, what we call the cycle of uses and material cascades. Frequently, this is out of the scope of life cycle assessment for buildings and materials. Valuables turn into obsoletes due to exergy and raw material loss, and the asset value (the building’s physical materials) diminishes. Instead of trying to add more value in the form of new buildings blocks that consume raw materials, water and exergy, why don’t we try to enhance the Retained Value of buildings? (retained value is a concept that I’m “borrowing” from Prof.Walter Stahel1). A smarter approach is not only possible, but needed.


Source: W. McDonough + Partners upon an idea of Stewart Brand

Source: W. McDonough + Partners upon an idea of Stewart Brand


Buildings as Material Banks

In the dawn of the 21st century we can’t accept that buildings are inherently not good for the people, the planet and business alike. The quality of the building can be enhanced during its lifespan by boosting the information it contains, not only on their living occupants, but in their physical components too. Thinking of buildings is systems thinking, and as in living metabolisms the flow of materials, energy and water determines the health of their metabolism. While the flow of energy and water in buildings can be easily perceived, the materials in and out are less visible. However, as already anticipated by Steward Brant2 some years ago, we can look at buildings as aggregates of systems with different Use Cycles3. The building blocks of one system – e.g. the building skin – will have the same durability as an entire system, but systems will differ in terms of utilization lifespans. The very concept of durability is redefined, and the building sustainability is not a static concept, but the sum of their sub-systems durability. We don’t discuss building sustainability anymore, but building circularity potential. Buildings are designed and performed as materials banks, keeping the value of materials by enhancing their exergy efficiency. Banks –good ones– deal with assets rather than obsoletes, the same as in “our” building analogs. 


Circular is the new pathway 

Not so long ago, reclaiming materials from buildings was common place. Temples and regular buildings used to interchange reclaimed materials in endless cycles, but at a slow pace. With the advent of modern times, the pace has changed and a more linear system has gained ground, exacerbating resource depletion of non- renewable sources (e.g. minerals) and making renewables (biological origin materials) not available for further uses with the same value, losing energy and water quality at every new stage. The extract-produce-waste linear system has contributed to the wealth of western societies, but at a cost: waste and liabilities for the current and future generations to come. If retained value is just the opposite to loss of value, a circular economy is the contrary of a linear economy.  

A Circular Economy is an economy restorative by intention and design, inspired by nature and that celebrates diversity of all sorts (biological, cultural and conceptual). When moving toward circular – or circle – buildings, the basis of design are to incorporate the definition of material use cycles and pathways. Quoting Walter Stahel, business relationships are not based on supply chains, but on new Supply Circles as well. By supply circles, we mean both the supply side – from suppliers to clients – and the recovering side – from clients to suppliers. The Circularity Potential of products and materials depend strongly on their design in the first place, logistics and business models. All these issues can be effectively addressed by the Cradle to Cradle Design Framework in order to: 


  • Design the elimination of waste, with products’ materials designed and optimized either for a Biological Cycle (cascading nutrients back to soil) or Technical Cycle (recovering materials as valuable nutrients back to factories and into new products or refurbished ones).
  • Use the current solar income in product and process.
  • Celebrate diversity in products and buildings alike.
  • System thinking design, including logistics and next life facilitators (e.g. tracking systems).
  • Develop business incentives for all stakeholders.


This is sometimes easier saying than doing, but all starts with asking the right questions. The construction materials industry is evolving rapidly in terms of Ecological and Social compliance, but there’s still quite a way to go to make material’s circularity a new standard and mainstream. The pace of doing so will strongly depend on business profitability and how to deal with externalities. While profit is considered a positive externality of the system, waste management, social and environmental liabilities are considered negative externalities. The pathway towards a Circular Business Model for buildings and cities needs to turn the negative externalities into positive ones, in a timely manner. 


Tracking Assets –the need for Smart recovery

Although it might be shocking to most people, good willing construction material manufacturers they don’t actually know what is in their products, at least not by 100%. This is one of the biggest challenges that the transition from a linear economy into a circular one is facing. Circular is not just about recycling, it’s really about retaining and – eventually – increasing the value of the assets. Decoupling growth from resource depletion needs less raw material consumption, and better energy and water stewardship, but none of this is really possible without enough Transparency in the industry. Transparency is the name of the game, and by sharing information about the chemical composition of products, we can make progress in this field. Chemical risk management is the key to avoid liabilities in the form of hazardous chemicals exposures to all stakeholders. But what is the best way to do that? This is a multistep process that inevitably starts with the inventory of chemicals, their assessment and optimization, within the context of their lifespan utilization. 


Asset Tracking 

Likewise tracking systems being used for metering energy and water consumption, resource efficiency, and all kind of interactions between occupants, buildings and cities, tracking materials and their components will provide a significant business opportunity. Sharing the information embedded in materials will save significant cost to all actors involved, and most importantly will decouple in the end the built environment from raw material extraction and depletion. Healthier and better materials and goods will find their way to better buildings, neighborhoods and cities, and the better and more reliable the information about them will be better for asset value retention. Lean manufacturing and logistics will benefit from asset tracking for the sake of the business circularity and profit. Smart cities should become the new El Dorado for Urban Mining, and circularity metrics would provide the appropriate input to make it happen. Exergy efficiency should do the rest…