This article originally appeared on the ARCHITECT website.
As concerns about climate change and humanity’s environmental footprint increase, carbon reduction will doubtless remain a prominent topic in 2019. Thankfully, certain scientists, manufacturers, and designers have acknowledged the problem, and many are taking steps to reduce greenhouse gas emissions with their products and research materials or methods.
The following list includes several recent material trends with the capacity to help change the carbon balance in 2019.
Discussions about carbon dioxide–emitting building materials all seem to focus on concrete—for good reason. Approximately 33 billion tons of concrete are produced worldwide every year, making it the second-most utilized material after water. Any serious effort to curb greenhouse gas emissions will require improving concrete’s environmental performance.
Piscataway, N.J.–based Solidia Technologies makes cement and concrete with significantly reduced carbon footprints. The company utilizes a cement recipe that generates less carbon dioxide than ordinary Portland cement (OPC), the industry benchmark. The chemical process forms silica and calcium-carbonate bonds between cement particles that are stronger than those in OPC. Notably, the Solidia Cement emits 30 percent fewer greenhouse gases than the Portland variety.
For its concrete offering, the company notes that the composite material sequesters carbon dioxide as it cures. Thus, in combination, the lower emissions and absorbed carbon add up to a 70 percent reduction in carbon footprint, a remarkable savings of 1.5 gigatonnes of carbon dioxide, according to the company.
Inflated Steel Structures
Fabrication represents another promising area for environmental improvement. Since 2003, Polish architect Oskar Zięta has been exploring the possibilities of inflating steel to create ultra-lightweight structures. Based on research conducted as a Ph.D. student at ETH Zurich, Zięta and colleague Philipp Dohmen devised a means to stabilize sheet metal by filling it with air. The process is named FiDU, short for “Freier innen Druck Umformung” (free inner pressure forming). The approach is demonstrated in the manufacture of the Plopp Stool, a three-legged seat composed entirely of thin steel sheets. Zięta's firm Zieta Prozessdesign fabricates the stool by laser-cutting templates out of the steel, welding sheets together at the edges, and inflating them from a single point—like a balloon—under high pressure. Impressively, the stool can support a load of two tons.
Zięta has utilized this technique not only to create a variety of furniture and accessories but also to erect occupiable structures. His NAWA pavilion, constructed on Daliowa Island in Wrocław, Poland, is a curvilinear vault structure composed of a series of inflated steel arches. Employing the same process as with the stool, Zięta Prozessdesign cut the arch plates, welded them together, and inflated them to create structural ribs with two points of contact with the ground. The final construction demonstrates what the architect calls “first FiDU manifesto in big scale”—a lightweight steel architecture made with pressurized air.
PET for Buildings
As I have written previously, the need to recycle plastics is now stronger than ever. Polyethylene terephthalate (PET), or type 1, plastic is the most recycled polymer today at a rate of just over 20 percent. However, PET is not a typical building material, so architects commonly specify plastics with much lower recycling rates (such as PVC, one of the most frequently used plastics in building construction, which has a recycling rate of about 2 percent).
The good news is that Armacell Benelux, a Belgium-based manufacturer of engineered foams, offers PET-based building products. The company’s ArmaForm Core material produces 34 percent lower carbon dioxide emissions compared with traditional PET foams—and considerably less than other polymer foams—and consists of 100 percent recycled content. Armacell offers a variety of PET building products including structural foam panels, thin sheet materials, and insulating foam cores. For example, the company’s structural foam panels consist exclusively of post-consumer PET bottle material and exhibit desirable properties for thermoformability, temperature resistance, and fatigue resistance. Armacell’s products are also 100 percent recyclable at the end of use.
Through a process remarkably similar to the carbon-fixing phenomenon found in plants, chemical engineering researchers at MIT and the University of California at Riverside have developed a carbon-negative material that continuously absorbs the greenhouse gas. The novel plastic converts carbon dioxide into a carbon-based reinforcing material, thus enabling it to become stronger over time and endowing it with self-healing properties.
“This is a completely new concept in materials science,” said MIT chemical engineering professor Michael Strano in a university press release. “What we call carbon-fixing materials don’t exist yet today” beyond the biological world, he added. The self-healing polymer does include a critical natural ingredient: chloroplasts, derived from spinach leaves, that catalyze the chemical conversion of carbon dioxide to glucose. The chloroplasts are incorporated into a gel made of aminopropyl methacrylamide and glucose oxidase, which gains strength as the cells convert sunlight into carbon.
Although the substance is not yet robust enough to serve a structural purpose, it has promising applications as a self-repairing coating. In time, the discovery may yield a variety of new lifelike building materials. “Materials science has never produced anything like this,” said Strano.
Another bio-inspired invention emulates the self-assembly capabilities and transformative mechanical properties of biological tissues. Scientists at Northwestern University have devised a material that can grow, assume different material properties, and, if desired, can return to its original state. The organic substance is composed of two types of molecules: peptides (amino acid compounds) and DNA-infused peptides. When combined, the molecules self-organize into intricate superstructures based on the inherent double helix-forming tendencies of DNA. The material starts as a soft hydrogel but becomes mechanically stronger over time as the internal structures self-replicate. Notably, these frameworks are hierarchical, similar to the way that muscle and bone are composed of multiple structures at different scales—a property rarely found in synthetic materials. By introducing a third molecule, the scientists can reverse the self-assembly process, thus demonstrating an unprecedented level of control over material properties without the need for energy-intensive procedures.
Although this bio-designed substance will not likely have commercial applications soon, it indicates a provocative future of self-organizing materials based on a biochemical—as opposed to a high-energy mechanical—approach. “Now that we know this is possible, other scientists can use their imagination and design new molecules in search of these new 'dynamic’ materials that reorganize internally on demand to change properties,” said materials science professor Samuel Stupp in a university press release.