Stitching Sustainability: How Researchers Are Using A Traditional Hobby to Combat Climate Change
Knitting sounds… kind of lame. But, what if this antiquated pastime could minimize the effects of climate change? It’s true. Knitting textiles has helped architects develop sustainable infrastructure, an area which has contributed to climate change, whether it be through waste, pollution, or resource depletion. In fact, in 2021, the construction industry contributed 40% of global emissions.
However, without realizing it, knitters, crocheters, and connoisseurs of the fabric arts use math to map their patterns. Working vice versa, researchers such as Hinke Osinga have crocheted “physical models of hard-to-visualize mathematical objects” like hyperbolic planes. As a result, these textiles can help visualize the intricate 3D geometries of the real world.
So, in 2019, architect researcher Mariana Popescu with ETH Zurich’s Block Research Group discovered a way of using these 3D geometries to find a sustainable way of designing infrastructure. First, they turned to structural geometry to reduce the amount of material needed.
Adding curvature to a structure allows it to hold more substance with the same amount of material. However, Popescu says, “If you really want to make good structures that use less material, you end up having complicated geometries that…have other features that are difficult to mold.”
This is where the textiles that fit 3D structural geometries come in. Popescu chose to use knitted textiles for the formwork. Knitted textiles can fill these curved, spatially complex 3D shapes, unlike woven textiles. They’re flexible, light, and require less support, allowing for “the design of very specific properties without… gluing, welding or stitching.”
These designs were prefabricated by knitting machines and turned into a knitting pattern by computation pipelines. The produced textile is then tensioned to form the shape and coated with a cement paste to create a lightweight formwork mold. No scaffolding was needed, creating a sustainable design-to-construction chain. Instead, Popescu’s team built a set of steel cables to hold the mold in place to cover with concrete - a traditional construction material.
First, they experimented using a lighter mold with a smaller, heavier bridge. It was successful, resulting in an unobstructed pathway as there was no need for support below. Then they tested it on an architectural scale with KnitCandela, a concrete shell structure built with textile formwork. Popescu described how the textile served two purposes: “an aesthetic exterior and a technical side that supported the geometry.” Even better, the formwork could be reused.
This research has future applications in construction. Besides saving time and money, these knitted textiles reduce carbon emissions during construction. The population has already hit 8 billion in 2022 and will continue to grow, so the solution isn’t to stop construction. Furthermore, these textile structures require less time to create compared to traditional formwork made of wood and foam and can be easily transported to places like war zones and natural disasters. While the cost of traditional formwork can range from one-half to one-third of the building’s cost, knitted formwork is cheaper. Ultimately, who knew knitting could prove to become a sustainable method of constructing buildings?
(2021, November). 40% of Global Emissions Come from Construction: Industry Leaders Discuss Vision for Change. BDC Magazine. https://bdcmagazine.com/2021/11/40-of-global-emissions-come-from-construction-industry-lead ers-discuss-vision-for-change/.
Juskalian, Russ. (2019, June 25). Mariana Popescu. MIT Technology Review. https://www.technologyreview.com/innovator/mariana-popescu/.
Klarreich, Erica. (2006, December 18). Crafty Geometry. Science News. https://www.sciencenews.org/article/crafty-geometry.
KnitCandela. Zaha Hadid Architects. https://www.zaha-hadid.com/design/knitcandela/.
Parametric Architecture. (2019, October 23). KnitCandela - 3D Concrete Pavilion by ETH Zurich and Zaha Hadid Architects [Video]. YouTube. https://youtube.com/watch?v=sOS1BNrJ-sI&si=EnSIkaIECMiOmarE
Popescu, Mariana. (2019). KnitCrete: Stay-in-place Knitted Fabric Formwork for Complex Concrete Structures. Research Collection. https://doi.org/10.3929/ethz-b-000408640.
Popescu, Mariana.(2019). KnitCrete: Stay-in-place Knitted Fabric Formwork for Complex Concrete Structures. BLOCK Research Group. https://block.arch.ethz.ch/brg/publications/962.
Ted x Talks. (2020, December 4). Knitting Architecture: Be Smart About Building Concrete Structures [Video]. YouTube. https://youtube.com/watch?v=UfVKdjdGBxg&si=EnSIkaIECMiOmarE.