Sustainable Shoe Design 101

Designing for a healthier planet is a lot like flying a mission to Mars: The stakes are high. The resources are finite. The path is uncharted. And that’s what makes it an adventure.

“Imagine us all in a spaceship, all in our space suits. Mine is purple velvet,” says Nike footwear designer James Zormeir. “And we’re just like, ‘Sh*t, we gotta fly this ship!’”

Zormeir co-piloted that metaphorical vessel with a resourceful crew of fellow innovators to create Space Hippie, a trash-to-trainers sneaker collection made with 25 to 50 percent recycled material by weight. Released in summer 2020, the collection has since paved the way for a new era of sustainability at Nike — and, hopefully, the world.

The team’s ambitious moonshot of a goal was to make a zero-carbon shoe — a task that would require innovative thinking every step of the way. While they did end up cutting their carbon footprint by over 70 percent (more on that later), they didn’t quite get to zero.

And that’s OK. For this team, the end result was important — but so were the lessons learned and data gathered along the way.

In order to absorb those insights, the team had to keep an open mind. “We weren’t sustainability experts going into the project,” says designer Haley Toelle. “Throughout the process, we were always asking questions.”

We know you have questions too. So, in the spirit of shared understanding as we all tackle the climate crisis together, here are five lessons that Space Hippie taught us about sustainability — and that we’ll carry forward to every experiment from here on out.

We hear about sustainability all the time, from clothing to cars to coffee beans. But what does it really mean?

The definition is hard to pin down because it’s not as clear-cut as an item being “sustainable” or “not sustainable.” A lot of factors come into play: what it’s made of, how it’s made, how it’s shipped. As a result, sustainability is more of a spectrum.

“There are so many ways to measure it,” says Toelle. “Whether it’s through water, carbon, labor practices. It can be really confusing — not only as a consumer, but as a designer — to know exactly where to focus.”

That’s why it was key for the Space Hippie team to pick a target early on. They decided to zero in on striving for a zero-carbon shoe. Noah Murphy-Reinhertz, design lead on the project, explains their rationale:

“There are two things we [as a society] can be doing: putting less carbon into the atmosphere, and taking carbon out of the atmosphere,” he says, breaking down climate action into simple terms. “We’ve got to be doing both. But [the former] is something we can literally do today.”

Wondering how carbon connects to all this? Whether you’re manufacturing high-tech semiconductors or just turning on your toaster, you’re likely burning carbon-rich fossil fuels to do so. The resulting greenhouse gas emissions, like carbon dioxide (CO2), trap heat from the sun in our atmosphere, becoming the main culprits for climate change. While some CO2 occurs naturally and is a good thing (fun fact: without the greenhouse effect, Earth would be a giant ball of ice!), the cranked-up amounts we’ve produced over the past 200 years are throwing things off-kilter.

While the team didn’t hit that zero-carbon goal (this time), the Space Hippie “04” model clocked in at about 3.7kg CO2e (that’s carbon dioxide equivalent, a standard measure for total carbon footprint). For context, making one pair adds the same amount of carbon to the environment as driving a car 9.2 miles or charging 472 smartphones.

Compared to an industry-standard shoe at over triple that (12.5kg CO2e, according to a Massachusetts Institute of Technology study), Space Hippie was a big step in the right direction. So how did the team land it?

One thing we know is that the lion’s share of Nike’s carbon footprint (more than 70 percent) comes from the materials we use.

To their advantage, the Space Hippie crew had some past sustainable material breakthroughs to build on. Like Flyknit, a Nike innovation that debuted in 2012, which reduces environmental impact by using recycled polyester yarn in a highly efficient knitted construction.

“You take a plastic bottle, shred it, melt it, then re-extrude it — and you’ve basically got new polyester,” says Murphy-Reinhertz, describing how Flyknit’s base material usually gets made. Sounds awesome, but there’s a catch: “There’s a lot of heat and energy in that process.”

That means that on the sustainability spectrum, Flyknit emits less carbon than most other shoe materials. But it still burns some. The team saw an opportunity to innovate further — by replacing 50 percent of Flyknit’s recycled-poly content with T-shirt scraps from the factory floor.

“We’re literally putting [the T-shirt scraps] through a wood-chipper type operation,” explains Murphy-Reinhertz. “There’s very little energy there. No heater, no big hydraulic press. You wind up with a bunch of fluff. We take that fluff, and we twist it together with that extruded plastic bottle.”

They called the new hybrid Space Waste — and its planet-friendly potential is major. “That yarn [gave us a] 70 percent carbon reduction versus typical recycled polyester,” says Murphy-Reinhertz. “It’s the one thing we did that had the biggest impact.”

Space Waste yarn gave the team a satisfying carbon-cut on the upper of the shoes. But they’d need more breakthroughs if they wanted to get closer to zero.

“Our coworker had started on Crater Foam way before,” says Toelle, referring to a material solution that would integrate about 10 percent Nike Grind — rubber scraps from the footwear manufacturing process — as filler within the oil-based foams that make up most shoe soles. “They were trying to get it more uniform, and it kept coming out really bubbly.”

But since the Space Hippie team’s goal was strictly sustainability, a look that implied progress over perfection was acceptable — even encouraged. “It created this crazy aesthetic, and instead of us trying to perfect it, we were like, let’s just roll with it,” recalls Toelle.

Zormeir was all-in on this function-first approach. “I’d always had this axe to grind with what I call industrial design’s finish fetish,” he says. “So, I was really pumped about Space Hippie being a challenge aesthetically — and us saying no, the roughness is part of this idea of radical transparency.”

Having a unique vision is one thing. But to make it a reality, the team had to bring others on board too.

“The Crater Foam itself has ‘flaws’ due to the Nike Grind filler,” says Zormeir. “What I call the ‘rainbow sprinkle cake’ effect.”

“This goes against everything anyone has been taught about what a well-manufactured shoe is,” says Toelle, referring to quality-control teams at Nike’s partner factories, for whom “flaws” usually equal red flags. “But we were saying, we actually like the wabi-sabi nature of the materials. The imperfections are part of their character — and part of creating less waste. Please don’t throw them out!”

Once production partners started understanding that the unconventional appearance was part of a larger mission to reduce carbon footprint, the positive spirit caught on — sometimes to an extreme degree.

“One of our factory developers in Korea got a Space Hippie tattoo,” says Zormeir. “And I’m totally going to get a matching one with him.”

“At first, the name was a joke,” Zormeir says of Space Hippie. “It just stuck. And it gave us [a mantra]: If it's not fun, it’s not Space Hippie.”

Inspired by the space-exploration concept of ISRU (in-situ resource utilization), cross-pollinated with 1970s environmental philosophy, the name gave the team more than just a slogan to latch onto. Outer space vibes and values became a way of life.

“One of our team members, Fanny, was like, ‘Oh, just Mars that sh*t,’” recalls Zormeir. “Like in the movies, you’re on Mars, you’ve just got duct tape and plastic…”

“And just having to hack it,” Toelle continues. “The process [instantly] became more fun.”

Whether leaving each other sticky notes scrawled with smiley faces and “stay wavy,” or shouting affirmations from across their noisy industrial workspace, the team vibe took hold and kept the crew moving forward — collaboratively.

“It felt like a space station where everybody's input mattered,” says Toelle. “Like we were working not just towards the design, but towards a critical mission.”

It all comes back to a sense of “urgent optimism” that doesn’t shy away from bad news about the environment, but instead asks what we’re going to do about it. “If you don’t have a positive vision of the future,” says Murphy-Reinhertz, “why would anybody want to join you on the journey to get there?”

“The real magic in [finding] different ways of making a shoe is what else it unlocks,” says Murphy-Reinhertz. In the case of Space Hippie, it’s meant a new level of information sharing and teamwork.

“These kinds of projects shouldn’t be super-secretive,” says Toelle. “They should [help] people feel empowered.” Nike started to open-source learnings in sustainability with a circular design guide published online in 2019 to help inform the decision-making of innovators everywhere. That spirit of sharing is only growing — across the industry and within our own walls.

“We started to get traction from people around the company in kind of a grassroots way,” says Toelle, remembering in-person conversations before COVID. “We have this funny closet of a conference room that we put Moroccan rugs in, and we’d have design meetings with everyone on the floor.”

Zormeir is the ultimate meeting host. “[We’d have on] weird ambient music, and be like, ‘Here, sit on the Moroccan pouffe.’ The ocean-breeze scent is in the diffuser. Now that everybody’s jacked-down a notch, let’s go ahead and have some real talk.”

The collaborative energy flowed both ways, with Earth-friendly ideas trickling out to other teams. We’re already starting to see Nike classics like Air Force 1s with Crater Foam midsoles, and a Jordan 1 High whose canvas upper uses Space Waste tech.

The halo effect can’t stop at Nike HQ, though. Zormeir sees an opportunity for products to spark positive conversation. When someone eyes your sneakers and asks, “‘Oh, what are those?’, that’s a conduit to talk about sustainability to people in a way that they wouldn’t have gotten to,” he says.

Toelle agrees: “In innovation, a lot of times the goal isn’t just to design an amazing shoe. It’s to tell a story, to inspire people — and the shoe is a tool for doing that.”