Down, synthetic or wool

Table of contents

• What is isolation?
• Down vs synthetic vs wool
• Combination of different insulation types
• Which is the best choice for you?

What is isolation?

Before we start, first the question: what exactly is insulation? In the outdoor world, by insulation we mean the ability to retain body heat on the one hand and protect the body from the cold from outside on the other. Both facets aim to keep you warm. Applications of insulation are therefore mainly found in clothing (e.g. jackets, ski trousers or gloves) and sleeping bags.

On the market, you will find different materials used to provide this insulation. The most common insulation materials in the outdoor world are down or synthetic in nature. Wool is also regularly (and increasingly) used as an insulation material. These materials have different properties, making one more desirable for one activity, but at the same time less suitable for another adventure. We will now look at this in more detail.

We can get to the most inhospitable places thanks in part to jackets with high-quality insulation. In this photo in the form of Mammut's Eigerjoch Pro IN Hooded jacket.

Down vs synthetic vs wool

As mentioned, in this blog we are going to compare the three types of insulation material mentioned above. But first, it is worth remembering that there are also big differences within each of these three types. Not all down is of the same quality. Not all synthetic fabrics have exactly the same properties. So take this knowledge into account when making the comparison below.

1. Heat-to-weight ratio

By heat-to-weight ratio, we mean the ratio of the amount of heat retained compared to a given amount of weight of insulation material. In other words, how much heat can you retain with 1kg of down, 1kg of synthetic insulation material or 1kg of wool. In this area, down is the undisputed winner. Using two sleeping bags from Mammut, you can see this clearly. The down sleeping bag Mammut Protect Down Bag has a fill weight of 950g a a limit temperature of -18°C, while the Mammut Protect Fiber Bag - a synthetic sleeping bag - needs a fill weight of 1770g for the same limit temperature. Wool is also no match for the warmth-to-weight ratio of down.

5. (Wear) comfort

Which material is best when it comes to (wearing) comfort is less undisputed. After all, this often also has something to do with personal preference. What we do know is that many people find a down sleeping bag more comfortable than the other variants. But when it comes to clothing, you hear this a lot less. Not entirely unimportant in terms of comfort is smell. This brings us to one of wool's strengths. Thanks to the protein molecules present in wool fibres, odour-forming bacteria are simply destroyed. It is therefore highly odour-resistant. Not only nice for you, but especially for your companions.

6. Lifespan

In terms of longevity, there is not really a clear winner. Down feathers are naturally durable, but down products tend to leak over time due to the small holes that can form in the upper fabric. Furthermore, this relatively thin upper fabric of down jackets can tear quite easily, causing you to lose a lot of down quickly. You can also damage the fill power of your down if you keep it compressed for too long.

Synthetic materials do not have the natural durability of down. They tend to slowly lose their shape and the fibres break down over time. Especially if they are frequently compressed. However, the upper fabric of synthetic insulation jackets is often sturdier and more hard-wearing, so they are less likely to tear when you scrape along rocks, for example. This obviously adds to the durability of the synthetic insulation jacket, but it has little to do with the properties of the synthetic insulation material. Insulation material made of wool scores a generous enough score when it comes to durability. In general, this material lasts longer than synthetic insulation material. Wool also suffers less than down from leakage.

Ortovox uses Swisswool as its insulation material, sourced from Swiss sheep.

7. Price

In terms of price, down is clearly the least attractive choice. Especially when it comes to down of the highest quality. The demand for it is high, while its supply is relatively low. It is not that insulation materials made of synthetic materials and wool are cheap, but prices are generally more attractive than down. Of course, there are also major differences within these types of insulation material. These are more or less related to its quality.

8. Sustainability & ethics

In terms of sustainability and ethics wool is the big winner, provided it is sourced to certain standards. For example, according to the Responsible Wool Standard. In principle, this also applies to down, of course. If it has been obtained according to the terms of the Responsible Down Standard, you can assume that it is ethically sourced down. The only problem is that there is only a limited amount of this type of down available. An increased demand of this also automatically creates a higher demand for less ethical down, which we discussed in detail in our previous blog

Synthetic insulation material is made from oil. Its production therefore releases greenhouse gases. Fortunately, we do see more and more brands opting to use recycled materials. Another problem with synthetic materials is that microplastics can be released during washing.

Combination of different insulation types

Some manufacturers make jackets and sleeping bags with a combination of several types of insulation materials. Grüezi Bag combines, for example, wool with both down and synthetic materials in many sleeping bags Fjällräven uses both down and polyester in some of their insulation jackets. This hybrid construction can give the benefits of both materials while limiting the imperfections of each. In some cases, the two types of insulation are combined in the same space, while in other cases the insulation may be in different areas of the jacket or sleeping bag. You can see the latter very clearly in some insulation jackets, where parts of the jacket that are more prone to accumulating moisture are filled with synthetic insulation material, while down filling is used in the other areas of the jacket.

Which is the best choice for you?

As you have read, each type of insulation material has its own advantages. It is important to choose an insulation jacket or sleeping bag that best suits the activity you have in mind. We hope we have made this search a lot easier for you by providing all this information. If you have any questions or would like advice on a particular sleeping bag or jacket? Then of course you can always contact our customer service team.