Building and Carbon

BY Alan Organschi 

Even as scientists continue to debate the defining characteristics of the Anthropocene — the historic moment of its inception and the very legitimacy of the concept itself — humanity teeters at an existential precipice of its own making. We have blanketed the planet’s surface, suffused its atmosphere, and penetrated its lithosphere with the chemical and physical signatures of our industrial and commercial activity. Across a range of scales, from paperclips to skyscrapers, the artifacts of our technological ingenuity — whether functional or obsolete — are the vestiges of our species’ unprecedented ability to create environmental problems through the processes of technical problem-solving. It is through this facility that we have endangered our own future, along with that of the other species who also inhabit the planet. As of the second decade of this current century, we’ve passed a critical and daunting threshold: Anthropogenic (human-made) material now outweighs the Earth’s biomass. 

Perhaps the most sublime — and certainly the heaviest — artifacts we have created are our cities. The steady aggregation of the buildings that form them and the infrastructural systems that enable their function continue to expand. Consider that Tokyo, the world’s most populous, continuous megalopolis, is also the largest stockpile of industrial material (according to industrial ecologists, the practitioners of a discipline that studies the flows of material and energy through the life cycle of manufactured products.) Extend that material stockpile to encompass all global metropoles such as Mexico City, Shanghai, Lagos, Quito, and Los Angeles, but also the discontinuous mat of suburban sprawl, and the smaller and denser conurbations arrayed around the planet’s currently habitable landscapes, and we begin to truly understand “human footprint” as fact as well as metaphor.  

As a final step in this thought exercise, picture the material consumption that will be required to house and otherwise shelter the activities of the 2.3 billion urban dwellers who demographers estimate will be added to the planet in the next quarter century. Even without the confirmation provided by the precise measurement of that anticipated demand, we can contend with the scale of our challenge, begin to assess our professional responsibility as the specifiers of that vast quantity of building material, and hopefully seize our potential agency — using the very process of dense urbanization as its fulcrum — in leveraging our practice to mitigate and even possibly reverse climate change and its correlated environmental impacts. 

Which brings us to the topic of carbon, of late and for good reason, the most attention-grabbing element in the chemical periodic table. As many of us remember from high school science class, carbon serves as the molecular building block of organic chemistry and therefore life on Earth. Bonded with two oxygen atoms, it forms carbon dioxide (CO2), a critical reagent in the complementary biochemical reactions of plant photosynthesis and, at radically different scales, both metabolic and industrial combustion. Despite its essential role in the once relatively balanced global exchange between atmospheric oxygen and carbon, we now recognize that CO2 has become the most dangerous form of human-generated waste. Compounding its overwhelming and steadily increasing atmospheric proliferation caused by fossil fuel combustion is carbon dioxide’s long half-life (compared to other perhaps more powerful greenhouse gases such as methane (CH4)). This means that the carbon dioxide we emit today will stay in the atmosphere, doing its work of trapping heat and raising global temperatures, for a long, long time.  

Our species’ relationship with carbon began nearly 400 million years ago, when, as precursors of contemporary forests, tree-like vascular plants arose from the lichens and mosses of the middle Devonian period. In those proto-forests, terrestrial life began to take shape. So did the revolutionary capacity of plants to photosynthesize an excess of atmospheric CO2 into life-sustaining oxygen and a dense carbohydrate that served as both structure for the plants themselves and fuel source for evolving insect and animal metabolisms.  

The subsequent Carboniferous period saw the rapid growth and expansion of early forests, but lacking oxygenated soil and the kinds of aerobic organisms that cause the decay of dead plant matter in our modern forest biomes, that carbon-rich, plant sediment slowly compacted. Through hundreds of millions of repeated cycles of forest plant life and mortality, under enormous geologic pressures and temperatures, those organic layers were transformed into the lithospheric deposits of fossil hydrocarbon — coal, oil, and gas — that humankind would burn to fuel an industrial revolution. In the somewhat narrower historic context of global construction, those temporarily abundant and cheap energy-dense fuels would in turn facilitate new means and methods of raw material extraction, manufacturing, and transport. This allowed for the smelting, sintering, and synthesis of whole new classes of energy- and emissions-intensive building materials such as cement and concrete, steel, glass, and plastics. 

The “carbon cycle,” the myriad bio- and geo-chemical pathways along which carbon moves through air, water, soil, rock, and the organisms that comprise life on our planet, was first described by Joseph Priestly and Antoine Lavoisier at the end of the 18th century.  

A little more than a century later, the Swedish scientist Svante Arrhenius suggested a link between fossil fuel combustion and atmospheric warming, a finding confirmed in an official scientific report to the American President Lyndon B. Johnson in 1967, early recognition that the homeostatic balance of the carbon cycle was being dangerously distorted.  

Despite efforts to suppress that vital information by the coal, oil, and gas industries and its automotive and petrochemical subsidiaries, environmentally conscientious architects and builders have sought over recent decades to counteract the climate impacts of their design and construction activities, attacking what they understood to be the main source of global warming that fell under their remit: the operational inefficiency of buildings.  

Mountains of fiberglass and mineral wool batting, oceans of plastic foam, acres of chemically synthesized, airtight but vapor-permeable membranes, vast expanses of tempered and laminated glass layered and insulated by inert gas fills, high-performance air-tempering and handling systems that evolved into costly edifices in and of themselves, new technologies of renewable energy generation and storage that would require difficult-to-attain rare earth metals and advanced, high-energy manufacturing techniques — all these were to become the material and technological bulwark against excess fossil fuel consumption.  

Air tightness, thermal insulation, and increasingly complex but refined mechanical means to temper interior environments and improve air quality in the operation of our buildings have been necessary measures in our sector’s battle against climate change. In the aggregate, however, it seems that reductions in operational carbon alone haven’t really moved the needle on building sustainability. So, we have arrived at what may be the key to reducing our impact: “embodied carbon.” This is all the greenhouse gas emitted during all the manufacturing and building activities that bracket a building’s operational service life and it is now a critical subject for building designers. 

According to recent assessments by the Intergovernmental Panel on Climate Change, the global building sector accounts for upwards of 40 percent of annual anthropogenic emissions when measured across the full extent of the building life cycle: the extraction of raw material; its transport, processing, and manufacture into building products and components; its assembly into buildings themselves, their operation, maintenance, repair, and, ultimately, their demolition and disposal. Due to an impending global building boom, by 2050 nearly half of building sector emissions will be embodied, generated by new building, the destruction of existing structures that we no longer value, and renovation of those we choose not to tear down.  

For our purposes then, as actors within a system we might loosely describe as the global building sector and, perhaps more grandly, as the form-givers of human settlement, it is critical that we recognize and acknowledge that carbon insinuates itself into every decision we make. Building designers, which is to say architects, but also structural and mechanical engineers, builders and contractors, real-estate developers, land-use and urban policymakers, must each carefully consider their role in directing the flow of carbon through the building life cycle and all along the chains of supply that feed our demand for the houses, offices, server farms, roads, bridges, telephone poles, etc., that comprise the constructed environments we envision. 

In light of this insidious implication of carbon emissions into all aspects of the building lifecycle, we must ask how best to approach the systemic decarbonization of our work and our discipline. This includes not only the building design and product specification process, but the way we choose to educate the next generation of professionals, the depth, rigor, and transparency of our impact assessments, and our advocacy for responsible material sourcing and tracing, accessible and reliable product data, fair but effective regulation, and accountability by our product manufacturers and suppliers. The list of design decisions that arise within our daily practice is seemingly infinite and their potential to mitigate impact is often hard to quantify. But each one, carefully weighed, will help us transcend business-as-usual sustainability.  

The tools of decarbonization lie ready at hand and we must commit to continually and critically evaluating their effectiveness. Building life cycle assessment, impact datasets, and third-party environmental declarations are essential to the complex measurement of carbon flows in building, but we should recognize their limits and understand the science that underpins them. Circular economic techniques that substitute different forms of consumer, industrial, or agricultural waste for virgin raw material will allow us to answer construction material demand in a resource-scarce future, but they should never encourage unsustainable practices by their source industries. We’ll need to understand the material stocks and flows, and their political economies to avoid that. Designing new buildings for future disassembly will extend the service life of their materials, components, and systems but the approach can’t serve as justification for the reflexive and indiscriminate demolition of existing building stocks and the sacrifice of their embodied carbon. Engineered, bio-based products such as mass timber, applied in dense urban configurations, offer the exciting possibility that buildings and cities could serve as massive carbon storage banks of biogenic carbon, but tracing that flow of wood fiber from regeneratively managed forests with strong safeguards is essential to ensure that the mass timber revolution doesn’t devolve into yet another extractive industrial practice.  

There is no singular solution without attendant cost, no magic bullet technology or methodology that should consume our focus, time, energy, or money at the expense of system thinking and systemic action. We know from practice that every building program, site, culture, regulatory climate zone, and political, social, and economic context is different, with various environmentally beneficial opportunities as well as burdensome constraints. Every ecosystem or resource pool from which we choose to draw material, whether it be a working forest or an industrial waste flow, has different limits, vulnerabilities, and knock-on effects. Each innovation in building will provide both replicable lessons and limited one-off solutions. We must be willing to assess and broadcast both our failures and our successes with transparency and vigor. The barriers to new practices and methods are painfully familiar and can seem insurmountable — the high initial cost of novel techniques and technologies, the rigid path dependencies of regulators, developers, builders, and our colleagues in the design professions, are impediments to invention and disincentives to environmental responsibility. Even our own concerns about the risk of unintended consequences can make it difficult to distinguish between what is circumstantially difficult and what is intrinsically (and measurably) beneficial.  

Seeking to solve the global carbon crisis will demand of our profession and our sector the kind of inventive problem-solving that has been the legacy of our architectural and building history. It will demand that we seek out and orchestrate trans-disciplinary collaborators from a range of relevant fields that have as yet played only marginal roles in our conventional design and building processes. Material scientists and foresters, complex system physicists and wildlife biologists, industrial ecologists and farmers may offer us critical, climate-restorative, and ecosystem-regenerative criteria for our decisions and choices. We are, after all, a profession of skilled orchestrators, adept at managing convoluted processes, taking advantage of a range of resources, and engaging often obscure knowledge networks to implement even the simplest of plans. We should embrace the complexity of the challenges we face as inspiration for a whole new kind of regenerative architecture and climate-positive building. 

Alan Organschi is principal and partner at the design, construction, and research firm GOA. He also serves on the faculty at the Yale School of Architecture and as Director of Global Labs at Bauhaus Earth in Berlin, Germany. 

DIAGRAM ATTRIBUTIONS 

1., 2. Reforming the Anthropocene from CARBON: A Field Manual for Building Designers (Kuittinen, Organschi, Ruff; Wiley) https://www.wiley.com/en-us/Carbon%3A+A+Field+Manual+for+Building+Designers-p-9781119720768 

3., 4. Wood Urbanism (Ibañez, Hutton, Moe, eds; Actar) 

DIAGRAM LABELS: 

Reforming the Anthropocene 

Carbon Flows in Buildings 

Building the Carbon positive City 

Biogenic carbon transfer