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Sustainability and circularity in the Built EnvironmentProblems and solutionsI have been lecturing and tutoring sustainability and circularity topics at a.o. TU Eindhoven for almost 20 years (a.o. the Circularity Certificate program). When I do so, I usually start with a definition that merges circularity and environmental sustainability, and a problem statement, as well as a brief vision on the role of technology versus economy and behavior, before reviewing a wide variety of (possible) solutions on multiple scale levels. This review goes from the level of society and (building) economy, to spatial planning (street, city, planet), to (existing and new) buildings, to elements and components, to virgin and recycled materials. It’s focus is on the how, but also on the (potential) impact, feasibility, and the horizon (i.e. the moment of impact). The above is outlined below. My teachings also consist of in-depth (critical) reviews of Life Cycle Analysis (and Carbon Impacts, and Circularity Indicators). For the sake of brevity, these assessment methods are not addressed in this article. . Problem statementJust the “Planet” part is hard enoughThe UN Sustainable Development Goals (SDG) and People Planet Profit (PPP) approaches aim to solve all humankind’s many problems. Not just ecological sustainability, but also social and economic issues (resolving poverty, equality, education, health, justice, etc.). However admirable, the objective of environmental sustainability and resource availability is really challenging enough as it is. So “just” this will be our objective and the focus and scope of this article; although economic, social, political and legal awareness and innovations are definitely required to reach our objectives, for technology alone is not going to save us. Renewability ratesThe below broad definition of “circularity” addresses not just closed loops for materials but also for energy, waste and emissions. According to Huesemann & Huesemann (2011), we have reached full circularity and sustainability when:
Interestingly, this definition effortlessly merges the notions of “circularity” and “sustainability”, where many other definitions have not reached this level of understanding. It is about rates and boundaries. Planetary boundariesThe problems of NOT living according to circular/sustainable standards, are displayed clearly in the Planetary Boundaries dashboard. Besides global warming, there are highly concerning overshoots in biochemical flows (nitrogen, phosphor), “novel entities” (chemical pollution, heavy metals release, plastics, etc.), land systems “change” (desertification, deforestation), and freshwater depletion and pollution. And as a consequence, there is a dramatic (genetic, functional) loss of biodiversity. While this view gives necessary useful information about the “whole” system, it is justified that we as Built Environment are mostly focused on global warming, as that is where we have most impact (we are responsible for and can mitigate 40% of all CO2-eq. emissions). The other problems are primarily caused by agriculture and industry. One other domain that we can act on is biodiversity (for example by creating biophilic cities). Resource depletionThe Planetary Boundaries approach is perfect for ecological monitoring, but it does not monitor the availability of resources. For materials circularity, we need other indicators. Mass (kg, ton) based indicators are widespread (“50% circular”), but should be rejected. One kilogram of clay is not the same as one kg of beryllium. Not in footprint, and not in availability. We need to offset (physical, technological, economic and geopolitical) availabilities versus the rate of depletion. Critical Raw Materials (CRM’s) reports show great urgency. At first sight they seem hardly relevant for the Built Environment (concrete, steel and timber are not scarce for the time being), but CRM’s are used in wind turbines, solar panels, batteries, and electronics, so this should make us think twice about scalability of renewables and the way we approach the key domain of energy transition. Technology versus economyPoliticians and corporations have high hopes (and high interests) to believe that technology is going to solve all of our problems. This is a blind and convenient assumption that needs critical reflection. Optimism and pessimism are both too simple. While some technological innovations will be crucial (e.g. harmless batteries, microbial protein, eco-restorative techniques, or passive building principles), others are certainly not (classical industries with lots of “shadow impacts”), and yet others should be met with critical skepticism (e.g. AI claims all sorts of future benefits, also for sustainability, while rapidly depleting Critical Raw Materials and sharply increasing energy consumption). There is good tech, bad tech, and maybe tech. Techno optimists tend to see only half of the picture. The share of renewable energy is higher than ever (this is what they see and say), but meanwhile the amount of fossil fuels being burned globally is growing (this is what they don’t see and/or don’t say). It looks good in relative terms, but in absolute numbers, renewables do not so much replace fossils, they are added on top. The reason for this is fairly simple: economic growth. Not just in developing economies such as China and India, but also in the West, where cars get ever bigger and drive more/further; houses get bigger, with all rooms being climatized 24/7; travel goes further ever more often. Ease and comfort are never questioned but constantly enhanced. The direct rebound effect says that once technology gets more efficient, it could theoretically lower impacts (techno optimists will tell that part of the story), but it might not: we will instead use more of it (lighting, heating, transport, devices, etc.), which will cancel out part of the progress. Should we not use more of that technology, we are still not on safe grounds: we might have lowered our impact on that account, but then we will spend our savings on other consumption. It is never enough, we are apparently unsatiable. Money will be spent, at some point, causing new impacts and depletions. This is the indirect rebound effect. Either technology should improve so much so radically, that it outpaces (for the time being) the subsequent growth of overall consumption; or government should limit consumption by regulation and taxation, to actually accomplish sustainability gains. Review of solutionsBefore getting into a review of numerous (possible) solutions, let’s create and introduce 3 key criteria:
These criteria together make it possible to evaluate, coordinate and prioritize solutions. The reviewed (possible) solutions below are categorized by scale level: society, spatial planning, old and new buildings, elements and components, raw materials. SOCIETYBeyond growthThe movements behind postgrowth, degrowth, economy of sufficiency and doughnut economy all target economic growth to eliminate ecological overshoots. This could mean a mere freeze, or going a step further and promote a redistribution of wealth (i.e. some groups can grow, others reduce consumption) to achieve social inequality and address historical debt or justice. Which version is favored is a matter of political ideology; but reducing growth is essential to solve our environmental problems. This strategy is however also in direct conflict with our present-day system: it requires a revolution or far reaching economic, political and cultural transition, not just here, but around the world.
Impact: very high Fair Price (i.e. including shadow costs)Shadow costs express either prevention costs (the money it would take to avoid negative impacts, for example by choosing green alternatives) or damage costs (the money it requires to avoid societal damage, such as dike improvements to battle rising water levels). Shadow costs are typically used as mathematical “trick” (“monetization”) to add the apples and pears that come out of a Life Cycle Analyses, e.g. Global Warming Potential; and Depletion of Resources, and arrive at one number. They are used to express the “total” environmental impacts of design/product/material A versus B, and then to pick the one with the best (read: least bad) environmental score. But they are not actually paid. Only in the case of the (European) carbon taxation do shadow costs get included in a Fair Price for goods and services. Paying a fair price has powerful consequences: some products and services get more expensive, others might get cheaper if they are restorative in nature. But also: if prevention costs are paid, they can be used to do the actual preventing.
Impact: very high SPATIAL PLANNINGClimate adaptationClimate adaptation does not aim to mitigate climate change, but seeks to prepare for it, and become more resilient. Examples are introducing more green in cities to deal with peak loads of rain as well as urban heat islands (while stimulating biodiversity), making rooms for rivers, shifts in spatial planning to favor higher grounds, and (bold) civil engineering interventions.
Impact: none on mitigation, high on adaptation Land + nature restorationEarth undergoes desertification, deforestation, pollution/degradation and biodiversity loss. But these processes can also be reversed. Deserts can become green again when retaining water (nomadic grazing also helps in some conditions). Forests can grow when the meat industry (being the driver behind deforestation in tropical forests) is revolutionized, by shifting to microbial protein or in vitro meat. Oceans and rivers can – to some extent - be cleaned from plastics, and chemicals. Industrial era agriculture can embrace ecological principles (with the help of precise agro-robotics). Dikes now have diverse vegetation rather than monotone grass. Cities adopt greenery in public space and in and on buildings. This is one of the more hopeful and positive angles.
Impact: very high Energy infrastructureSpatial and urban planning relies heavily on new energy infrastructure, such as heat nets (hot residue water), power grids (electricity), and gas pipes (biogas, possibly hydrogen in the future), combined with supply and storage stations on various scale levels. This new infrastructure includes interesting innovations such as asphalt solar collectors and pv panels on parking lots and between rails. The production and implementation impacts of these are offset with the subsequent ongoing benefits.
Impact: high Mobility and transportationMobility (automotive, airplanes, ships, etc.) makes up a quarter of global greenhouse gas emissions). Shipping is linked to global trade (currently undergoing changes). Flights are mostly linked to tourism and other reasons for travel (study, work), which seem to become ever more affordable for ever more global citizens. Breakthrough technological would help a lot here. Automotive is closer to home. Electric cars effectively cut carbon emissions, but (still) rely on Critical Raw Materials. The low-tech reduction strategy would be to switch to hikes, bikes and public transport, which takes financial and cultural-behavioral incentives besides spatial measures.
Impact: very high BUILDINGSDenser use of buildingsThere is a housing crisis in The Netherlands. Some say we need 1 million new houses in 2030. But there is also another take on this: we can use houses more efficiently. Many people live alone or with just two as singles, divorcees or elderly parents in a house that was built for a whole family. Dutch people inhabit substantially more m2 floor area than ever before in history, and also much more than neighboring countries. These are mismatches in the housing market, but the problem is not merely physical. There are financial penalties on moving in together for those receiving benefits, there are obstructions (banks, corporations) on subletting a room, and legal obligations to hold ownership of a vacant first house while in fact living in a second house on a “holiday park”. Taking away these obstacles would solve roughly one third of the problem. A similar approach can be taken towards office buildings. On average only one third to maximum one half of their capacity is employed in work week hours! Sharing, or splitting, enhanced by transformable adaptable interiors and good social architecture, can significantly reduce the impacts of the real estate sector.
Impact: high Durable designGood buildings last longer. The longevity of buildings depends on the quality of architecture (is the building loved and appreciated?) and the social conditions (Bijlmer decayed due to social-economic problems rather than isolated design issues, although the design did allow the problems). The longevity of buildings also depends on the match between demand and supply. Houses that are too small or factories or offices that are no longer in demand all create a mismatch and decrease the lifespan of buildings. The answers to this are found in flexibility (the same building can accommodate several functions, without big adaptations) and adaptability (adaptations can easily be made). Open Buildings combine these strategies, to create Transformable (interior) Monuments (infra)structure). They are moreover strongly rooted in the legacy of TU Eindhoven, starting with John Habraken and currently Tom Frantzen as his heir. Open, flexible, adaptable buildings typically require doing a bit more (surplus in structure, infrastructure, collective spaces) at the start, and they also have some impacts in transformations (interior replacements) while earning back these upfront investments in the longer term, as the structure lasts longer.
Impact: looking at just materials impacts, medium RetrofittingApproximately 30% of global carbon emissions is caused by heating, cooling, lighting and ventilating buildings. Since new buildings are “near zero (operational) energy”, this amount rests on existing stock. Retrofitting old buildings (globally) is therefore still the most effective measure to mitigate greenhouse gas emissions.
Impact: very high User behaviorUser behavior should also be addressed. Simple yet effective measures such as shading or operating windows according to outside conditions are poorly understood, and energy-efficient buildings invite higher comfort levels rather than just energy conservation (e.g. 24/7 heating/cooling in all rooms of the house while wearing a t-shirt).
Impact: medium Low-tech passive buildingsNewly constructed near Zero Energy Buildings also bring another challenge. Their energy use is (potentially) low, but their embodied impacts (e.g. embodied carbon) are markedly higher than those of old buildings, due to the much-increased use of metals (HVAC, photovoltaic panels, batteries, heat pump, smart grid, etc.), as well as double/triple glass and insulation. PV, wind turbines, batteries and the like also require Critical Raw Materials. Passive design goes a long way to reduce the operational energy demand without inviting lots of embodied investments.
Impact: medium ELEMENTS AND COMPONENTSReuse nowApplying used (second hand) materials and products right now, has a substantial positive impact right now. It saves the mining/sourcing and manufacturing impacts (most prominently carbon emissions, resource depletion) of new/virgin materials.
Impact: high, looking at just materials impacts DemountabilityDesign for disassembly (demountability) has no beneficial impact now, but it facilitates reuse later (at the End-of-Life stage). Demountability requires alternatives for particularly the habit of concrete casting. Most other materials and products are already based on (dis)assembly.
Impact: high, looking at just material impacts Biological materialsBiological materials (this phrasing is preferred over “biobased”, as that can have many non-biological additives) have several interesting advantages. One is that they are renewable (within a rate, there is a maximum harvest and a limited amount of space and nutrients). While finite resources are gone or entirely in circulation at some point, the volume of biological materials can grow, and facilitate some economic growth “forever”. Surely enough, renewability is futile in case of deforestation. Tropical rainforests are indeed in serious decline, but that is not due to a demand for construction materials, but due to agriculture, biofuels, biomass incineration. These practices should definitely be addressed, with urgency, but not by our discipline. Forests on the northern hemisphere are in contrast growing in volume (not in biodiversity unfortunately, they are largely monocultures), enough even to build all new houses (t)here with just a very small portion of annual excess harvest. This number goes down even further when applying lightweight timber frames instead of solid timber panels. Another property of biological materials is that the trees or crops took carbon dioxide from the atmosphere while growing. There are fierce debates on whether wood is therefore “carbon negative” or rather carbon neutral (the materials will ultimately release carbon back into the atmosphere at the moment of incineration or composting). What is often overlooked is that forestry is only carbon negative as long as the amount of biomass increases. Stable volumes do not release nor take carbon into/from the atmosphere. Global Warming is best mitigated by additions to nature. Either way, if we assume stable volumes of biomass (stationary forests and croplands), biological materials are close to “carbon neutral”, as their harvesting, transport and production impacts are fairly low.
Impact: medium Lightweight designLightweight design is a very straightforward strategy to use less resources, hence lower the impacts of production and mitigate resource depletion. It however works only if the applied material has low impacts in the first place. Aluminum is very light and material efficient, but still has very high carbon emissions and shadow costs despite that feature. But for concrete, lightweight is a very promising direction. Per kg, concrete is actually very innocent in terms of embodied carbon and ecological costs. It is the immense volume of concrete that is employed, that gives it such a bad reputation (which is not entirely fair; the built environment consists of numerous large objects such as buildings, roads, tunnels, bridges and paved surfaces; so, the big volume is inherent). Topology optimization is a promising relevant direction. For timber, using lightweight instead of solid panels means the impact is even lower, and the less forest we need for production, the more can be left to flourish as nature.
Impact: medium MATERIALSInnovations in the production of materialsInnovations in production of materials provides gains per kg. Examples are cement substitution, carbon curing and dense packing for concrete; hisarna process for steel; and efficient forestry for wood. Any improvement makes a big difference, and all of these should be developed. However, it is highly unlikely that the gains per kg will beat the substantial global growth in resource consumption (our processes may become 10% or 20% “cleaner” but meanwhile we might use 30% or 50% more to build all those new cities).
Impact: medium to high, looking at just materials impacts Innovations in recyclingThe Smart crusher process is an interesting innovation in concrete recycling. Traditional crushing breaks the concrete in smaller parts, with limited application (typically becomes roadbed, which is a case of downcycling), but smart crushing breaks the cement, resulting in a pile of gravel, a pile of sand, and a pile of reacted (can be reversed chemically) and unreacted cement. Ready to be used for new concrete without quality loss. Recycling – and by extension, “circularity” – also provides a dangerous illusion. If we reuse or recycle everything we have today, and we do so forever, we still need substantial amounts of virgin resource production, to cover for global economic growth. For The Netherlands goes that demolition materials cover only 40% of new construction. The steel industry likes to say that – indeed - they have very high production impacts, but steel can be recycled (which is true, goes for other materials too) and then have a much lower negative impact (which is also true, although it is still at the high end). The reality is however that 69% of steel has a virgin source. Demand should be reduced by a factor 3 to close the loops and go by secondary resources. This is a factor 5 for aluminum. For Critical Raw Materials (used in solar, wind, batteries, and electronics) the number will be even much higher.
Impact: medium to high, looking at just materials impacts ConclusionThe problem analysis provides a lens onto causes and consequences, and seeks to end confusion. Reviewing (potential) solutions with the criteria impact, feasibility and horizon makes it clear what can and cannot be expected from these approaches. This article aims to promote effective efforts. |