JULIA LOUIS-DREYFUS has earned a new nickname on the set of her new HBO hit, “Veep” and it‘s NOT Elaine!

She’s the Eco-Warrior!

The 51-year-old actress/ environmental activist patrolled the set of the political comedy like a police sergeant, demanding that co-stars and crew minimize their carbon footprint during filming, say sources.

“Julia was desperate to make sure ‘Veep’ stayed ‘green,’ ” one source told The ENQUIRER. “She was insistent that all the show’s stars should recycle their old scripts and made sure all the bottled water containers were packed up and taken to a recycling facility.

“She was militant.”

Julia even told her :My Girl" co-star Anna Chlumsky that they should carpool together, in Julia’s electric car, of course!

“Julia earned the nickname ‘Eco-Warrior’ because it’s all she ever talked about when she wasn’t filming,” the source continued.

It’s not the first time the sitcom actress has attempted to persuade her cast mates to go green.

In September 2011, The ENQUIRER reported that Julia tried to convince her former “Seinfeld” co-star Jerry Seinfeld to become more energy efficient. But sources revealed that the opinionated comic, who owns a fleet of gas-guzzling cars – mostly vintage Porsches – didn’t want to hear it.

A source said: “JERRY JOKED to Julia that he isn’t ready to become a tree-hugger just yet, and that she should leave all the green stuff to Captain Planet!

“She was fuming that he made light of the situation.

"Julia’s a funny lady, but she’s dead serious about the environment.”