There are a plethora of companies that offer broad manifestos and advice on living better — Lululemon, the workout apparel company popular with yogis, even puts these words on its bags.

But now, thousands of yoga pants-wearing customers are demanding that Lululemon put its money where its mouth is.

The company is facing backlash from Yoga teachers around the world in the form of an open letter who are demanding that the company change its primary method of powering energy — burning coal — in its factories to something more sustainable.

“Lululemon’s marketing claims its clothes are ‘designed by yogis’ and offers connection to a global community of mindfulness practitioners, sporting leaders, and health and wellness professionals,” the letter states. “Lululemon’s reliance on coal as a source of energy is extremely harmful to people and the environment, particularly in countries like Vietnam, Cambodia, China, Sri Lanka, and Bangladesh, where its products are made.”

As of late Tuesday afternoon, 1,698 Yoga teachers had signed the letter.

The advocates allege that the company’s GHG emissions are growing, not slowing down, as the company continues to expand, noting that Lululemon is “one of the largest, fastest growing and most profitable fitness apparel brands in the world.”

The group is calling for an aggressive “100 percent use of renewable energy” to be used in factories around the world.

The letter comes just days after outdoor retailer Patagonia founder Yvon Chouinard pledged to give away his brand, valued at $3 billion, to a trust in order to fight climate change.

Lululemon was down over 21% in a one-year period as of late Tuesday afternoon.