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

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

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

“Lululemon’s marketing claims that its clothing is ‘designed by yogis’ and connects to a global community of mindfulness practitioners, sports leaders and health and wellness professionals,” the letter said. states. “Lululemon’s reliance on coal as an energy source is extremely damaging to people and the environment, especially in countries such as Vietnam, Cambodia, China, Sri Lanka and Bangladesh, where the products are made.”

Late on Tuesday afternoon, 1,698 yoga teachers had signed the letter.

Its advocates argue that the company’s GHG emissions are growing and not slowing down as the company continues to grow, 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” for use in factories around the world.

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

lululemon was down more than 21% in a period of one year from late Tuesday afternoon.