Ten minutes into the first dune climb, I waited for it: that clammy creep down my back. It never came. I run warm, and most insulated jackets and I do not get along, so the Mammut Aenergy Air IN had something to prove. It felt like wearing a duvet, yet I could push hard into a steady westerly wind while the Dutch weather changed its mind every half hour.
The verdict after testing in the dunes and in town: the Mammut Aenergy Air IN Hooded Jacket earns an 8.6/10. Its Loopinsulation Active, a 100% recycled insulation, delivers duvet-like comfort with outstanding breathability for people who generate heat. It is not an expedition jacket, but it works as a daily autumn jacket and a winter mid-layer in the mountains. The main drawback is the missing hem adjustment, and at €320 it sits firmly in the premium segment.
Summary: Mammut Aenergy Air IN Hooded Jacket
- Product: Mammut Aenergy Air IN Hooded Jacket
- Overall score: 8.6/10
- Best for: Active hikers who run warm and want one jacket for both the trail and the city
- Biggest plus: Exceptional breathability under effort, without the clammy feeling
- Biggest minus: No hem adjustment to seal out the wind around the hips
- Price: €320 (RRP)
How Mammut positions the Aenergy Air IN between mountain and city
I connect Mammut with serious mountain kit. So I was curious how a Swiss brand with more than 160 years of alpine pedigree would handle a jacket that also belongs in town. Mammut is clearly leaning into recycled materials and everyday wear, but without the loud styling some other labels go for. In black, the Aenergy Air IN simply looks quietly capable. That restraint, I think, is exactly the point.
How does the Mammut Aenergy Air IN fit, and how comfortable is it?
The first thing I noticed was the feel. The fabric is extremely soft, like pulling a duvet or a favourite blanket around your shoulders. Even so, at 513 grams in size L, the jacket feels light and airy.
The cut is athletic and moves with you. The hood fits snugly, keeps the wind out and stays put when a strong gust comes in. One thing I missed was a way to cinch the hem tighter around my hips. It is a small detail, because the overall fit is good, but in the wind I wanted to pull it in just a notch.
What is Loopinsulation Active and how warm is the Aenergy Air IN?
Mammut fills this jacket with Loopinsulation Active. This is a 100% recycled insulation made from offcuts of its own rope production and recycled PET, which gives waste a second life. Its stretchy, accordion-like structure stays closed when you stop and opens up when you move. We explained the technology in detail in our deep dive into Mammut Loopinsulation Active.
The Aenergy Air IN is not expedition-warm, and it does not pretend to be. It is warm enough for daily autumn wear and works well as a mid-layer for winter in the mountains. Instead of carrying one jacket for the break and another for the climb, this one is designed to do both jobs. In my experience, it achieves exactly that.
Pockets, two-way zip and packability: the practical features
In daily use, I liked the large zipped side pockets most. They sit high enough to work with a backpack hip belt. The chest pocket easily holds a phone and keys. The jacket also has a two-way zip and packs down into its own bag, so you can stash it in your day pack on warmer days.
How breathable is the Aenergy Air IN on a windy dune hike?
My test day was properly Dutch: a hike through the dunes at 8 to 10 degrees, with a steady westerly wind and constantly changing conditions. Because I run warm, an insulated jacket normally leaves me clammy and overheated within minutes.
Not this time. I could put in real effort without that sweaty feeling, and that is when I understood how breathable this jacket really is. On the exposed stretches the wind stayed out. Whenever I stopped, the warmth came back quickly.
Does the Aenergy Air IN’s water-repellent finish handle light rain?
In town, the jacket surprised me again when I got caught in a light shower. I expected the soft fabric to soak it up, but the water beaded on the surface. There is clearly a water-repellent finish. It is a welcome bonus, but for proper rain you still need to pack a shell.
How does the Mammut Aenergy Air IN look in everyday use?
I got more comments on this jacket than on anything I usually wear. Colleagues and others remarked on how good it looked and how comfortable it seemed. I had not expected that from the understated black version, but it is definitely a plus in my book.
Verdict: who should buy the Mammut Aenergy Air IN?
This jacket won me over. It is comfortable, breathable and understated, and it feels at home both on the trail and in the city. If you run warm and want one insulated jacket for active autumn days and winter layering, the Mammut Aenergy Air IN is a do-it-all piece I can highly recommend. If you need expedition warmth or real rain protection, look elsewhere or add a shell.
Quick answers about the Mammut Aenergy Air IN
- Is the Mammut Aenergy Air IN warm enough for winter?
As a standalone jacket, it suits cool autumn days. In winter it works best as a mid-layer under a shell. - Is the Aenergy Air IN waterproof?
No. It has a water-repellent finish that handles a light shower, but you need a shell for proper rain. - What is the Mammut Aenergy Air IN made of?
The insulation, lining and face fabric are recycled. Loopinsulation Active uses rope-production offcuts and recycled PET. - How much does the Mammut Aenergy Air IN weigh?
My size L weighs 513 grams.
