In their endless quest to tinker with, rethink, and perfect the ultimate alpine layering systems, Patagonia has arrived at some real winners over the years. Now that fleece is fully out of fashion, the race has been on to arrive at a better solution.

Enter the category of “active insulation”—warm but breathable jackets that can get soaked with sweat during aerobic output, or even take a beating from meltwater on a mixed climb, and still dry out surprisingly quickly.

Patagonia really broke trail into this category with the Nano Air hoody, which I reviewed in Chamonix several years ago, and have been using as my consistent pile jacket ever since. This year, Patagonia has produced an updated version of the Nano Air—streamlining it, and making it as functionally high performance as possible.

Introducing the Patagonia Nano Air Light hoody—easily one of the most outstanding achievements in this new category of “active insulation” that I’ve seen. (Currently, this piece, at $250, is for sale only at Patagonia.)

Nano Air LightPatagonia Nano Air Light

Simple Thermodynamics

The real key to achieving high-performance active insulation is an element of balance. Too much insulation, and the jacket can feel bulky, keep you too warm, and lose its mobility and climbing performance. Too little insulation, and you’ll just end up adding more layers that just detract from the jacket’s intended functionality.

As its name implies, the Patagonia Nano Air Light is a lighter version of the Nano Air—a little less insulation, and a little more performance. It also differs in that it’s a three-quarters-zipper pullover with no hand pockets (just one chest pocket). It’s also given a much slimmer fit, making it feel not so bulky.

There are also a few other small differences, including the form-fitting woven cuffs on the sleeves, which slide right into outer (waterproof) layers or into the gauntlet of a glove really well.

Patagonia uses 40 grams of what it has dubbed “Full Range” insulation—a multi-directional stretchy fabric that feels as cozy as your favorite hoody, but is built to withstand the rigors of high-output climbing, skiing, and mountaineering. Having tested other companies’ active-insulating jackets, I can attest to the difference of Full Range insulation. I like it the best. It moves well, stretches the right amount, breathes well, keeps me warm, and comes out of the washing machine feeling brand new every time.

Field Testing the Patagonia Nano Air Light

After four months of testing the Patagonia Nano Air Light, I’ve found it to strike that perfect mid-layer balance. I’ve tested it as an outer layer during uphill ski mountaineering in 20-degree conditions, with just a single wool base layer underneath, and was perfectly comfortable. I’ve also worn it underneath a Gore-Tex jacket for downhill skiing, and found that it didn’t create any uncomfortable bulk (including with the hood).

I’ve also climbed a number of rock pitches in 30-degree weather in this layer and I’ve managed to stay warm and still perform at a normal level in this jacket. The sleek cuffs on the sleeves are great for dipping in a chalk bag, and the form-fitting jacket fits neatly under a harness, and stays put.

In retrospect, as much as I’ve enjoyed the Nano Air Light’s precursor, the Nano Air, I have realized it’s a little too warm for uphill slogging, and a little too light to be a good belay jacket. The Nano Air Light is the ultimate mid-layer.

In the future, I’d love to see a full zipper jacket built with 40 grams of Full Range insulation. I’d also love to see a looser crew-style sweatshirt—no zipper—made out of Full Range that’s specifically designed for cold-weather rock climbers, perhaps with sleek warming pockets that can be accessed cross-body in the sides/armpits of the shirt (so you can warm one hand up while holding onto the rock with the other).

Bottom Line

If you’re a fan of active insulation, and you liked the Nano Air, I highly recommend upgrading to the Nano Air Light. If you’re anything like me, you’ll discover that it’s the single piece you’ll end up using and wearing the most.

Share

WHERE TO BUY