Serena Williams served as a guest judge alongside host Karlie Kloss for the Bravo series' finale runway show

By Morgan M. Evans
March 12, 2020 03:07 PM

Just like most fashion trends, on Project Runway, one day you’re in and the next day, you’re out.

But when it comes to designers looking to help save the planet — that’s one trend that is here to stay. Just ask fashion industry stars Serena Williams and Karlie Kloss.

The tennis champion joined Project Runway judges Brandon Maxwell, Nina Garcia, Elaine Welteroth, mentor Christian Siriano and host Kloss, as a guest judge for the series’ final runway show during New York Fashion Week.

In the episode, each of the finalists displayed uniquely special collections, but there was one designer who championed sustainable fashion, and Williams thinks that is a trend that will never go out of style. (To find out which collection it was, you’ll have to tune in to the finale, tonight on Bravo!)

“I think it kind of has to stay,” the designer and tennis star said. “We have to somehow figure out how to live on this planet and not destroy it and so this really speaks to me personally. It has to be incorporated into design as well because fashion is a really big part of a lot of bad things that are happening and it’s just the honest truth, so it’s about how do you create those collections that are more sustainable and takes less pressure from what we do.”

Karlie Kloss on Project Runway

Agreeing with the 23-time grand slam champion, Kloss, 27, said she was happy to see the sustainable trend transforming into more of a lifestyle.

“I am so glad it is at the forefront of the conversation in our industry and on the planet right now and I think it needs to continue to be,” the model said, adding that more industry power players need to be more aware of manufacturing practices. “Just being more cautious of how fabrics are created and re-using fabrics,” Kloss told PEOPLE while praising the same designer Williams highlighted for their zero-waste collection.

“I think it is as small as the decisions we make every day — what we choose to buy and how we get dressed. I think for me, I am really cautious and I think that is the first step,” the Express collaborator continued. “Something even like denim and the amount of water that goes into creating denim — I’m much more cautious of rewearing and repurposing my denim instead of buying a new thing and there’s lots of small things people can do to collectively like that to make a big impact.”

While at the February taping of the finale, the S by Serena designer — who previously presented her Spring 2020 collection at an event with Vogue editor-in-chief Anna Wintour — told PEOPLE what it was like to be on the opposite end of the runway as a Project Runway judge.

Designer Serena Williams speaks with Anna Wintour during the S By Serena Presentation during New York Fashion Week
Dia Dipasupil/Getty

“It’s definitely different. You grow up looking up to people like Anna and so many amazing fashion designers and now you’re just in the room making decisions and it’s different,” Williams, 38, told PEOPLE. “You grow and you’re doing what you want to do and I think this is just us reaching our goals.”

On Thursday night’s episode of the Bravo fashion series, Williams and the Project Runway judges will decide which of the remaining four finalists — Victoria Cocieru, Geoffrey Mac, Nancy Volpe-Beringer and Sergio Guadarrama — will show their collections at NYFW and who will be named the season 18 winner.

Find out who makes it to the runway at 9:00 p.m. ET on Bravo.