Fast-fashion brands have revolutionized our closets and changed our parameters. Once upon a time, a 30-euro T-shirt was considered a bargain. Now even half that price would still be considered costly.

But since environmental activists started drawing attention to the high environmental price of bargains, eco-fashion has become the new trend - and all clothing companies want to be part of it.

H&M, for instance, one of the major fast-fashion companies - is currently carrying out World Recycle Week (18 - 24 April), aiming to collect at least 1,000 tons of old clothes.

But with big brands getting more sustainable, organic fashion spreading and second-hand shops increasing, the decision on where to buy the most earth-friendly clothing has become far from easy.

DW visited three fashion producers in Cologne, Germany, with very different eco-initiatives: H&M, Green Guerillas and Humana. Kirsten Brodde, project leader of the Greenpeace 'Detox my fashion' campaign, guided us through the complex world of sustainable fashion.

H&M World Recycle Week aims to recycle tons of old clothes around the world

Sustainable fast-fashion: a first step

Our first stop was at H&M. Yes, it is a big fast-fashion company. But it is also among the greenest, according to Greenpeace. "H&M is working towards sustainability and making real efforts," Brodde told DW.

The current green advertisement 'World Recycle Week' on H&M's store window seems to fit with this idea: recycle your old clothes and get a discount coupon as a reward for your green action.

But this time, environmentalists have not been entirely convinced. And none of the managers was willing to talk to DW.

"H&M's recycling week is a week of illusions since only one percent of collected clothes can be used as recycled fibers," said Brodde. "Working on extending the life of clothing is more important than inviting consumers to recycle their clothes and buy new ones."

The company says it will keep working for a sustainable fashion future. But according to Brodde, fast-fashion will never be sustainable. "Sustainability is contradictory with selling huge amounts of clothing," she is convinced

Organic fashion: a step forward

"Organic fashion should be produced without any textile chemicals," explained Brodde. "And clothing collections in such a store should be almost timeless and able to survive for a long time."

From the wood to the electricity, everything is said to be sustainable at Green Guerillas

So, leaving the big brands behind, we visited Green Guerillas, an organic and fair trade clothing store.

"Our products are certified by the Global Organic Textile Standards (GOTS)," Marlies Binder, owner of the store, told DW.

That means a big reduction in the use of chemical products, a total ban on critical substances such as toxic heavy metals or genetically modified organisms (GMO), and strict procedures to minimize waste.

Marlies believes the clothes she sells are produced to have a long life, and most of them are backed by initiatives for recycling and reusing. In addition, Green Guerillas only count on up to four collections per year - two main ones and two smaller ones.

Brodde reminds us that mass production of organic fashion could eat up all the progress achieved compared to traditional fashion.

Second-hand: the final step

For our last stop, we have chosen a fashion concept, in which production plays a minimal role. Humana is a worldwide second-hand chain aimed at supporting development projects in Asia and Africa.

Some of the H&M old clothes end up in HUMANA shops

In Germany alone, around 50 tons of clothes are collected per week and then distributed through the different stores and sent to the projects in Africa and Asia, according to Anne Marie Madsen, HUMANA regional manager:

"There is no need to produce a lot of clothing, it is already there," Madsen believes. "We have limited resources in the world and we don't have an extra planet to spare."

According to HUMANA, one t-shirt needs four tons of resources - including water and oil - to be produced, while a second-hand garment only requires 30 grams for the whole process of repair and distribution.

Madsen is delighted that over the last decade more people have started buying in second-hand shops - and are proud of it. "Ten years ago, customers did not want HUMANA bags. Now they walk proudly on the streets with it," Madsen said. "People are learning, this is a good development," she added.

This ADIDAS vintage jacket is a piece of proud for Madsen

After our little excursion into the world of fashion, one thing is clear: most actors are working towards a new sustainability approach in fashion. But the speed with which we "consume" the products is far from eco-friendly.

"In the end, it is all about slowing down the fashion industry," Brodde concluded.