From PET bottles to insulation: What's inside our underquilts

Part 3 of our series: An honest look at our sustainability decisions

The previous part of our series on materials, production, and the decisions behind them was all about what surrounds a product: packaging, or as little of it as possible. This time we’re looking at what’s inside: the insulation in our underquilts.

If you’re wondering what an underquilt is and which of our models is right for you, we explain this in detail in this post.

What actually keeps you warm if not down?

For our Moonquilt Compact and Moonblanket Compact, as well as the Moonquilt Allround , we use Thermore® insulation called Ecodown, with a weight of 115 g/m². The fibers in it are made from 100% recycled polyester from PET bottles.

It is important to us to be precise: it is the insulation fibers that are made from 100% recycled material, not the entire underquilt. The outer fabric, sewing thread, and other components are not included. We do not want to promise more than is actually there.

How a bottle becomes insulation

The process behind it: used PET bottles are collected, sorted, cleaned, and processed into polyester fibers. These fibers are turned into a lightweight, warming insulation fleece – exactly what provides warmth in our underquilts later on, without any down.

Thermore has Ecodown certified under the Global Recycled Standard (GRS), among others, as well as according to OEKO-TEX® Standard 100 and bluesign®. For anyone who wants to read the details: Thermore website. 

Why this makes a difference at all

The fact that PET is fundamentally highly recyclable does not mean that this happens everywhere. Recycling rates for PET bottles vary widely worldwide.

In Germany , around 97.6% of PET beverage bottles were sent for recycling in 2023. After accounting for processing losses, the net recycling rate was 95%.¹ In contrast, in 2020, only around 27% of plastic bottles in the USA were collected for recycling.²

Many PET bottles are still not recycled, but instead burned or landfilled, for example. If used PET bottles are instead processed into insulation fibers, they get another use before the material eventually becomes waste.

And to be honest: We don’t use recycled fibers everywhere

Despite our enthusiasm for PET insulation, we don’t want to pretend that this is the whole story. Our Moonquilt Pro models are filled with down, not recycled polyester. Down has certain properties (for example, in terms of the warmth-to-weight ratio) that recycled synthetic material cannot yet fully replace. That is why we continue to use it there.

This doesn’t fit perfectly with a post that is actually about recycled material. And that is exactly what we want to be honest about. We make compromises here, as does probably every brand that deals honestly with the topic. What we can do within this framework: The down in the Moonquilt Pro is RDS-certified (Responsible Down Standard). Specifically, this means: no force-feeding and no live-plucking. The standard also requires independent inspections and documented traceability of certified materials throughout the supply chain.³

RDS is primarily an animal welfare and traceability standard and says nothing about how resource-intensive down production is overall. However, it means that when sourcing our down, we rely on clear, externally verified standards. Both materials come with different benefits and challenges – and that is exactly why we look more closely at our choice of materials.

Just one building block

Different materials for different requirements: some underquilts with insulation made from recycled PET bottles, others with RDS-certified down, because we cannot yet fully combine both. That is exactly the point of this series: We do not want to claim that we have already found the perfect solution everywhere, but rather show what decisions are behind it and why we make them.

Insulation is just one of many building blocks. How and where we manufacture our products, from Bali to our European warehouse, is the next part of this series.

Sources

1. GVM Gesellschaft für Verpackungsmarktforschung (2024): Aufkommen und Verwertung von PET-Getränkeflaschen in Deutschland 2023, p. 33, accessed on 21.10.2026
2. World Economic Forum (2022): World recycling facts for 2022: Plastic, paper and more, accessed on 21.10.2026
3. Textile Exchange: Responsible Down Standard (RDS), accessed on 21.10.2026
   The RDS is a voluntary international standard for animal welfare in the duck and goose supply chain, as well as for the traceability of down and feathers from the certified facility to the final product. Individual sites are audited annually by independent certification bodies; live-plucking and force-feeding are prohibited.