CLO Values Explained: Primaloft, Coreloft, Thermatek & More

In summary, the CLO value of synthetic insulation shows you how warm your jacket is. Sure, it’s not the only parameter affecting your warmth. But, almost the most important one and, unfortunately, the hardest to achieve... Because producers rarely share CLO values for their items. And trying to find them on the Internet is really time-consuming. So I decided to create a detailed table with publicly available CLO values of synthetic insulations. Also, I calculated these values for insulated jackets made of them.

If you need more info about synthetic insulations’ CLO values and other characteristics, keep reading it.

Synthetic Insulations

Synthetic insulators are typically designed to mimic down's properties.

Ultra-fine fibers in their structure create heat-trapping air pockets, keeping your body heat... though not as good as natural fillings [1].

But, when it comes to water resistance, they don't collapse and lose their insulating power when wet, unlike down jackets. Also, their drying time is shorter.

So, I'd say synthetic insulated jackets might be good choices for damp conditions or high-output activities. And, you can clean them easier than those with down.

Plus, they're more affordable and hypoallergenic. But still, keep in mind that synthetic jackets are less packable and heavier than down ones.

How Warm Are Synthetic Insulated Jackets?

Truth be told, it's pretty tough to tell how warm a synthetic insulated jacket is.

For a start, I'd say you'll need more synthetic insulation than natural down to achieve the same warmth. It means your ultra-warm synthetic jacket will likely be heavier than its down counterpart.

Of course, you'll want to wear lightweight synthetic jackets during high-intensity activities. To offset the weight, some brands use lighter insulations in their jackets, like 40 g/m². Or only in the jacket's sleeves, hood, and neck.

These active insulation jackets sacrifice a little warmth but still can work great trapping air. Also, they're remarkably breathable. My best picks in this category are Arc'teryx Proton LT and Patagonia Nano-Air. 

What is a CLO?

CLO value is an important factor in determining a synthetic jacket’s warmth. Metaphorically, like FP * FW value in down jackets…And the higher the value is, the warmer the insulation is.

Synthetic insulators provide more insulation per thickness. This is why any insulation can achieve desired CLO value after setting the right amount of thickness. But of course, your jacket will become heavier in the end.

Manufacturers rarely share the CLO values of their products. Let's say they disclosed these values; which standard did they use to measure them? To correctly be able to compare them, this info is also crucial.

Against all odds, I combed through the CLO values of synthetic insulators. And, to give you some ideas about jackets' warmth, I've prepared a detailed table.

But, I'd like to point out that I got the values from forums like Reddit and producers' technical data sheets and catalogs. That is, they aren't based on scientific investigations and aren't totally reliable.

In the table, you'll see some calculations related to synthetic insulated jackets. For example, the Patagonia Nano Puff Hoody contains the Primaloft Gold Eco having 0.92 clo/oz/yd². And the jacket's insulation amount is 1.77 oz/yd². So,

Calculated CLO of Patagonia Nano Puff Hoody = 0.92 x 1.77 = 1.63

As I said earlier, some jackets have different insulation weights on various parts. So, I calculated the CLO values considering the percentage of their body surface area covered [2].

Synthetic Insulation Types

There are three major categories of nonwoven insulations: Short-staple, continuous filament, and cluster fiber. Also, it's possible to knit synthetic insulations.

Nonwoven Insulations

Short-staple insulation

These insulators feature densely packed short fibers to trap air and keep your body heat. But, the fibers can move around and form cold spots.

Short-staple fillings provide a soft feeling. They're compressible and have good warmth-to-weight performance. But, they can lose their insulating ability faster than other synthetic ones. Meaning that you might need a new jacket after a while.

PrimaLoft, Coreloft Compact, and Thinsulate are examples of short-staple insulation.

Continuous filament insulation

These insulations are made from continuous filament fibers.

They’re stiffer and less packable than short-staple insulators. But, their web structure is more durable and retains loft longer.

Climashield, Coreloft Continuous, and PlumaFill are at the forefront of the market.

Cluster fiber insulation

There are small fiber tufts in this insulation type. They're designed for closely mimicking down to minimize heat loss.

The North Face ThermoBall Eco and Freudenberg comfortemp are examples.

Knitted Insulations

These insulations don't need to be quilted because they're self-supporting knitted structures. So, the jacket's outer layer doesn't have to be high-density to keep the insulation.

After all, the jackets with knitted insulators are highly breathable. That’s why they're convenient for high-output activities.

But, to put it bluntly, they won't offer excellent insulation performance.

Polartec, Octa Loft, and Pontetorto are well-known knit insulations.

What Kind of Synthetic Insulation is Best for You?

As I mentioned above, various synthetic insulation producers are on the market. And each brand features a lot of varieties in their product range.

Let’s look at the most widely used synthetic insulations in a little more detail.

After that, it is up to you to choose!

PrimaLoft

PrimaLoft is a well-known brand in short-staple insulation. It has three main categories: Gold, Silver, and Black.

And they've tons of subcategories...

PrimaLoft Gold insulators have the highest CLO values among others. And that way, they might maintain your warmth even in harsh weather.

Generally speaking, PrimaLoft Silver ones display slightly worse insulation performance. So I'd say they'll be appropriate for wearing in a little warmer climates.

And the PrimaLoft Black is the most basic insulation. You can opt for a jacket with this insulation for everyday use.

PrimaLoft also designs insulators in collaboration with some outdoor clothing brands. LifaLoft (Helly Hansen) and ThermoBall Eco (The North Face) are some of them.

By the way, I'd like to say I have been impressed with PrimaLoft's cross-core technology. The aerogel used could enhance your warmth without increasing your jacket's weight. Patagonia DAS Parka and L.L. Bean Primaloft Packaway are examples.

Climashield

Climashield produces continuous fiber insulations made of long and hollow fibers.

Filaments in their structure allow recovery after applying forces during stretching or washing. So, they might help maintain the insulation performance of your jacket for a long time.

The company has a wide variety of insulations like Climashield Apex, Contur, Prism…

Each insulation has a prominent characteristic. For example, Climashield Apex is touted as lightweight warmth. And Climashield Prism is a high-performance insulation material produced using AquaBan technology. So, it can repel water effectively.

Speaking of which, Arc'teryx ThermaTek is thought to be a rebrand of Climashield Prism.

Coreloft

Coreloft is synthetic insulation used exclusively by Arc'teryx. There are two kinds of this insulation: Coreloft Compact and Coreloft Continuous.

The Coreloft Compact is thought to be a rebrand of Thermore Classic. And the Coreloft Continuous is of Climashield APEX.

The Coreloft Compact is made of staple fibers in various sizes that are crimped to trap air for more warmth. It's compressible and soft but might lose loft faster because of short fibers.

As you might guess from its name, the Coreloft Continuous includes filament fibers in the structure. That’s why it features higher integrity and more durability. But you can compress it less. Also, I'd say this insulation has some limits on its weight.

You can compare Arc’teryx synthetic insulated jackets using its comparison page.

FullRange & PlumaFill

Exclusive to Patagonia, FullRange is a product of Toray Mills, Japan. This is why it’s believed to be a rebrand of Toray 3DeFX+.

FullRange, which is quite stretchy and breathable, includes multi-denier polyester fibers. For now, Patagonia uses this insulator only in Nano-Air products.

PlumaFill is another innovative synthetic insulation of Patagonia. Microfilaments in this insulator spiral a central fiber to mimic down very well. It’s pretty warm and compressible. You might want to check out this page for more info.

Conclusion

Your synthetic insulated jacket's warmth is mainly related to its insulation's CLO value. And the higher the value is, the warmer you feel.

But, companies infrequently share their products' CLO values. And finding them is a bit challenging and time-consuming.

So, I prepared a table with publicly available CLO values of synthetic insulators. And I added the calculated CLOs for synthetic jackets to the table. Also, you can find some details in the post about the common synthetic insulations in the market, like Primaloft, Climashield, etc.

I hope this information will help you when choosing a synthetic insulated jacket.

I recommend you also check out my other post, "Best Synthetic Insulated Jackets".