TODAY, THERE IS A WIDE RANGE OF CARBON-NEGATIVE MATERIALS ON THE MARKET THAT CAN HELP BUILDING PROJECTS MAKE A POSITIVE IMPACT ON THE ENVIRONMENT.
Carbon neutral. Climate positive. Carbon negative. Energy positive. Regenerative.
This medley of terms may be hard to grasp, and it may be difficult to distinguish one from the other, but the terms are appearing with increasing frequency in our conversations about the built environment and in the goals being set for architectural projects today.
As a starting point, carbon neutrality aims to balance an entity’s carbon dioxide emissions with emissions that it either reduced or sequestered over the course of its life. Climate positivity and carbon negativity (often used interchangeably), on the other hand, tip the scales much further. Carbon-negative materials, products, construction, and systems actually draw away or reduce greater quantities of carbon dioxide from the atmosphere than they generate in the first place — leading to outcomes that are truly “positive” and regenerative for the environment.
With that in mind, architects and designers who set out to achieve carbon-negative status for buildings today are considering not only the emissions generated during the construction, lifetime, and decommissioning of a building, but the embodied carbon of all materials used on the project. In their quest for a much lower carbon footprint, architectural studios are building the mechanisms for clean energy generation and reduced emissions into their designs, while actively seeking out and utilizing a palette of cutting-edge materials that are inherently carbon negative.
This is where things get exciting. Emerging from businesses led by interdisciplinary teams of scientists, engineers, architects, builders, artists, and biologists is a new breed of high-performing and climate-positive materials. Whether being crafted by established manufacturers or rising start-ups, these are materials whose ingredients or manufacturing processes have already sequestered or reduced carbon dioxide in the environment. There are still others in this growing field that are designed to actively capture emissions and toxins from the environment over the course of their lifetime and use.
The palette of such materials is diverse, from masonry blocks that have eliminated the need for heat-intensive firing and curing to boldly patterned concrete floor tiles whose colorants come from captured air pollution and soot, to robust panels for facades which have been molded from landfill-oriented plastic waste — to name just a few. The carbon-negative material solutions we are seeing today are scalable, inching closer to the price point of conventional materials, and suited for large and commercial applications. They include: substitutes for concrete (a highly polluting but essential material); new composites for interior walls, floors, and surfaces; modular waste-based panels for facades; and even bio-integrated solutions that incorporate living matter such as moss, mycelium, algae, and bacteria.
As architects, designers, and builders practicing in Texas, we have a clear motivation for exploring all of these material solutions for use in projects in the state and beyond. For one, the state’s carbon footprint is enormous: In 2016, Texas emitted almost twice as much carbon dioxide as the next-highest state in the country, California — 653 million metric tons compared with 361 million metric tons. While the Lone Star State tops the list of the nation’s biggest carbon polluters, it is also home to some of the country’s most prominent design firms, who are driving large-scale architectural projects in the state and globally. This presents an enormous opportunity to drive change, and to both test and implement a variety of carbon-negative material solutions. Presented here are a few product types and innovative materials that are particularly exciting to consider today.
When it comes to cladding or panels for facades, there is a wealth of carbon-negative and low-carbon material solutions being developed. A personal favorite is the biochar-based thermoplastic material developed by Berlin-based Made of Air (MOA). The company taps into waste biomass, such as wood waste from the timber industry and crop residue, and then, via a process of pyrolysis in an oxygen-free environment, transforms this into a biochar and combines it with a bio-binder. The resulting material (composed of 90 percent atmospheric carbon) is robust and suitable for all traditional thermoforming methods, allowing it to be used for detailed exterior paneling for facades, interior surfaces, furniture, automobile components, consumer goods, and more. The dense, smooth, fire-retardant material presents itself as a sustainable alternative for use in these applications. At the end of their life, these panels and three-dimensional forms cast from MOA’s biodegradable material can be shredded and sequestered in the earth. This cycle can be repeated continually, allowing for more and more atmospheric carbon to be directed into the earth.
MOA’s material is primed for use in the built environment, with several pilot projects already underway — one focused on facades and one on furniture. The company is currently working with Audi to develop panels for the facade walls at its iconic dealerships and has already tested the panels in a live project at Munich Airport intended to clarify how the material behaves in an external environment. What makes this material a double win in terms of climate positivity is the fact that the making of MOA materials also generates a surplus of usable heat and electric energy, in addition to the carbon captured by its raw materials. This energy can go on to serve other manufacturing processes or external applications, further reducing overall CO2 emissions.
In the Netherlands, Pretty Plastic has developed an eponymous, beautifully marbled, modular facade tile. This cladding is composed of recycled PVC material and gives discarded building products a second life. The recycled PVC is sourced from old window frames, downspouts, and rain gutters, among other plastic waste. The silvery and steely-grey diamond-shaped tiles are highly robust and suitable for facades and roofs; they are also easy to install and deinstall, as they are simply screwed onto a wooden framework. The design and materiality of the tiles capitalizes on the inherent longevity of plastic, delivering a product that has a long lifespan and can be removed and recycled again and again. In this way, the tiles are actively contributing to the circular economy and the goal of carbon negativity. The 100 percent recycled-material-based tiles are available in nine luxurious shades and, since their launch in 2019, have already been implemented in projects such as schools and permanent exhibition pavilions in the Netherlands.
Far from the world of plastics is the natural material hemp, the chief ingredient of UK-based Margent Farm’s hemp fiber corrugated panels. Hemp is a plant that aggressively captures carbon dioxide as it grows, absorbing and converting it to biomass while releasing oxygen, a process that sequesters carbon and regenerates its environment by doing so. Hemp is also high in cellulose content (60–70 percent of the plant), making it a strong and durable ingredient for corrugated panels. Margent Farm’s corrugated panels are made of hemp fibers that have been bound together in a bio-resin matrix, where the resin itself is made principally from farm waste such as oat hulls, bagasse, and corn cob. These hemp fiber corrugated panels offer a natural and carbon-negative alternative to corrugated steel, PVC, bitumen, and cement in architecture and interior design applications. The textured, rich brown panels can be used externally to create rain screen facades or as a ceiling or wall lining in interiors, and even as an acoustic treatment. Though being produced only in moderate quantities at Margent Farm, these carbon-sequestering panels are available in sizes as large as 1,200-mm-by-1,050-mm.
Several new masonry products today are trying to tackle the concrete — or, more specifically, cement — problem. The cement industry accounts for approximately 8 percent of global carbon dioxide emissions, which can be attributed to its manufacturing process and the massive scale of its consumption: Concrete is the most consumed substance in the world, second only to water. In an effort to reduce our dependence on concrete, while still achieving equivalent strength and durability, innovative new variants and substitutes are appearing.
North Carolina-based start-up Biomason is leading the way with their bioLITH tile. Eliminating the need for curing and firing, as in a traditional concrete masonry unit, bioLITH is a tile based on “biocement,” which has been grown using natural organisms. While traditional Portland cement releases carbon during production, Biomason’s process captures and utilizes carbon instead, in a method inspired by nature — one much like the growth of corals. To achieve this, the team at Biomason combines carbon and calcium to produce a biologically formed limestone-like material which, even at ambient temperature, yields a structural cement. Their biocement material consists of roughly 85 percent granite from recycled sources and 15 percent biologically grown limestone they develop. The result is an array of precast bioLITH tiles, which can be used in both exterior and interior applications in a variety of building types. The tiles are already being offered in a number of natural and gray hues, brushed and polished finishes, and varied sizes. Most significantly, the bioLITH tiles are the lowest carbon footprint cement tile on the market today, actively contributing to architecture’s battle against climate change. The tiles have already been used in residential and institutional projects, among them the Dropbox headquarters.
Another pathway is to create concrete masonry blocks but use lesser volumes of conventional cement and turn to manufacturing processes with less embodied energy. California-based Watershed Materials has developed a market-ready product called the Watershed Block, which uses up to 50 percent less cement in its production and offers a 65 percent reduction in embodied energy when compared to conventional concrete masonry. Watershed Materials achieves this via a combination of the following: integrating 100 percent recycled, locally sourced materials as aggregate instead of virgin mined rock (which needs energy and water to prepare) and folding in natural mineral based geopolymers. A range of different colored blocks is created as part of the company’s strategy to produce low-cost, low-cement masonry from a wide range of materials, including locally sourced minerals, quarry byproducts, and even recycled concrete. These Watershed Blocks have a significantly lower carbon footprint than do ordinary concrete blocks, yet they offer equivalent structural performance, while their textured, varied aesthetic is a bonus.
In the case of Netherlands-based StoneCycling, its WasteBasedBricks address the issue of carbon footprints dually. As the name suggests, the exotically colored, shaded and speckled bricks and slips are made from waste — with all varieties made from at least 60 percent waste sourced from construction and demolition debris from the building industry. Preventing this bulky debris from going to landfills is a climate-positive step, which is augmented by the fact that the production of StoneCycling’s bricks has been CO2 compensated through offsetting by the company. If the sustainability and waste content of these bricks don’t draw you in, their sheer variety of hues, surface finishes and effects, and trendy names (such as Wasabi, Truffle, Nougat, and Pistachio) surely will. The bricks have already been used in projects around the world — for interiors and exteriors, in residential and commercial applications, and for both walls and flooring.
Interior Walls and Floors
This is a rapidly expanding realm, where start-ups, individual designers, and large manufacturers are all constantly innovating to create products ranging from carpets to paints, to wall paneling — all with a lower carbon footprint than before. Nothing captures this trend better than the work that Mumbai, India-based design and material innovation start-up Carbon Craft Design is doing. In 2019, the company launched Carbon Tile, the first tile to be made with carbon emissions. They achieved this in collaboration with Graviky Labs, the makers of AIR-INK, who have been pioneers in recycling carbon emissions. Each beautifully patterned, graphic Carbon Tile is equivalent to cleaning 30,000 liters of air, providing a full day’s worth of clean air for one person, or preventing 15 minutes of car pollution. To create the tiles, captured air pollution is first processed to remove harmful heavy metal impurities and then fused with a mixture of cement and marble derivatives. The whole process consumes less energy than do conventional tiles. The resulting products are robust, meet all specifications for cement floor tiles, and are suitable for both residential and large-scale commercial applications. Uniquely pattered in a combination of white, gray, and black hues, the floor tiles are offered in two series: premium range IndusTile and standard range IdenTile, whose patterns are designed to reflect the unique identities of cities like New Delhi, London, New York, and Beijing.
Another simple and easy-to-implement material solution involves Graphenstone’s Ecosphere and Biosphere paint lines, which are suitable for use on interior and exterior walls and surfaces. By combining a natural, artisanal lime base with the supermaterial Graphene, the result is a highly resistant and long-lasting paint that is breathable, avoids condensation, is washable, does not yellow, and, most importantly, absorbs carbon dioxide. This is made possible because of its ingredients: Natural lime-based paint has existed and been used for hundreds of years and has always absorbed carbon dioxide during its carbonation process, helping reduce the volume in the air. By adding Graphene fibers to the blend, the paint becomes ultra-durable and can perform this role better and for longer. With the use of these ecological paints, the interiors and exteriors of homes or commercial spaces start to perform the role of adult trees, removing polluting carbon dioxide from the environment.
Meanwhile, Israel-based materials company Criaterra has developed “Advanced Earth Technology” and is producing a range of wall tiles and three-dimensional forms made entirely from diverse natural earths, vegetal fibers, and minerals. The tiles offer the same strength as do their cement and ceramic counterparts, but with a fraction of the energy use and emissions. Instead of firing materials, Criaterra’s manufacturing process aims at compacted “living” material that is pigmented with natural colorants and can simply biodegrade and return to the earth as nutrients at the end of its life. While catering to large-scale projects and offering aesthetic diversity in terms of colors, shapes, and textures, Criaterra’s wall tiles and 3-D forms, such as blocks and furniture elements, are highly resistant and durable, and achieve a 90 percent energy savings when compared to ceramics and a 92 percent greenhouse gas savings when compared to cement.
From living walls to fungal mycelium-based acoustic treatments, the inclusion of biological elements in architectural products is becoming increasingly common. Working in tandem with nature and building in living raw materials allows these products to achieve higher performance with lower energy requirements and emissions, simply by capitalizing on the properties that nature has to offer. The presence of living material can actively draw out carbon dioxide from indoor and outdoor environments while helping improve the sense of health and well-being for building or space occupants through biophilia.
Among relevant examples in this category are the mycelium-based acoustic tiles from Italian company Mogu. Grown in molds and on a base of textile residue, these fungal mycelium panels match the acoustic and fire ratings of synthetic materials and are easily installed and removed, all while offering a new, beautiful aesthetic and a diversity of shapes. The energy use and emissions are strongly reduced due to a growth and waste-based manufacturing process, while the panels themselves can return to the earth at the end of their lives and biodegrade with ease.
At the other end of the spectrum is the work of the young UK-based designer Poppy Pippin, whose terracotta Moss Tiles are a beautiful representation of what living facades can accomplish. Cast in an arresting concentric ring pattern, the grooves in the tiles encourage the growth of moss, which in turn has the ability to draw out carbon dioxide in urban environments, making facades an active, living tool for carbon sequestration.
These carbon-negative solutions are inspiring and encouraging, but the question is, what next? The architecture and design community in Texas can start to consider which of these materials or similar innovations create the maximum impact while still offering viable volumes for real-time projects and a digestible price tag. The case for implementing these materials, even the speculative and early-stage products, is strong. According to numbers from the U.S. Energy Information Administration, Texas produces about 12.7 percent of the nation’s carbon dioxide.
Putting aside the numbers for a moment, the unexpected and damaging winter storm that Texas experienced this February is undisputed evidence that the climate is changing. With greenhouse gas emissions as the chief contributors of such change, we can no longer wait to implement low-carbon solutions in every dimension of life in the state — from construction and infrastructure to manufacturing and transportation, to energy generation and use. Architecture in Texas offers the perfect canvas to test and roll out these solutions. There is not only a wealth of building opportunities but also plenty of patronage for innovative and prototypical architecture, which can pave the way for use of these materials at all scales, residential to institutional.
After contemplating these many globally and nationally sourced carbon-negative materials, it will be exciting to witness how and where they are implemented, both within the state and in design originating from here, and how their use will contribute to a broader low-carbon future.
Purva Chawla is founder and partner of the design consultancy MaterialDriven, which is based in Dallas, London, and Bilbao, Spain.