Down jacket and thermal insulation: how to choose the right one?

When practicing outdoor activities, choosing the right down jacket is essential to ensure both comfort and performance. Whether you're climbing a mountain, spending a day skiing, or bivouacking in the great outdoors, thermal insulation and moisture management play a key role. Between down, synthetic wadding, weight, breathability, and other technical criteria, it's not always easy to navigate. This article guides you through the different aspects to consider when choosing the ideal down jacket, based on your activity and needs.

During an outdoor activity, our body acts like a real boiler, producing heat through metabolism and muscular effort . But this heat is constantly threatened by external elements: it escapes by radiation, dissipates on contact with cold air by convection, leaks at the slightest contact with an icy surface by conduction, and disappears in the form of sweat by evaporation. To maintain a stable body temperature around 37°C , the body adjusts blood circulation by heating or cooling the skin as needed. In the mountains or in cold weather, these mechanisms are put to the test, and poor thermal balance can quickly lead to discomfort, even hypothermia. The challenge? Finding the right equipment to keep warm when it's cold, without overheating during exercise .

One of the biggest challenges in the mountains or in cold weather is fighting against body cooling , especially when the effort diminishes: a prolonged break, reaching the summit or an ill-planned bivouac can quickly cause body temperature to drop. Humidity – whether from rain, snow or perspiration – accentuates this heat loss. Wind, on the other hand, further reinforces this icy sensation with the wind chill effect, making the temperature seem much lower than it actually is.

To deal with this, it is essential to adopt the three-layer system : a breathable first layer to wick away moisture, an insulating layer to retain heat (like a warm down jacket suitable for exercise), and a windproof and water-repellent outer layer to protect against the elements. This is where the technical down jacket comes into play: designed for extreme conditions, it offers a good compromise between insulation, breathability and lightness. And to combine performance and commitment, eco-responsible down jackets , made from recycled materials, allow you to stay warm while limiting your environmental impact. Choosing the right down jacket and knowing when to put it on is therefore crucial to avoid ending up wet, cold... and potentially in danger.

If the cold is a threat in the mountains, excess heat is just as much. Too much intensity can lead to excessive sweating, with a double consequence: a loss of water and mineral salts, and above all, wet clothes that will become freezing when you stop. Sweating in winter means condemning yourself to shivering later . Cold air, in addition, reduces the sensation of thirst, which can lead to progressive dehydration , affecting performance and increasing the risk of hypothermia.

The solution? Anticipate and regulate your body temperature . Adjust your pace to avoid excessive sweating, but also use ventilation zippers and adjust your layers accordingly. For example, Lagoped waterproof jackets are equipped with underarm zippers to allow ventilation without compromising protection. Finally, drinking regularly, even when you're not thirsty, is essential for maintaining good fluid balance.

In the mountains, wind is an invisible but formidable enemy. It accelerates body heat loss by replacing warm air in contact with the skin with cold air, a phenomenon known as "windchill." In concrete terms, a temperature of 0°C with a 30 km/h wind feels like -10°C, making the cold feel much more biting than it actually is. The stronger the wind, the faster heat loss accelerates, increasing the risk of chilling and hypothermia.

To protect yourself from this, it is essential to wear a windproof outer layer , such as a softshell jacket for intense efforts or a waterproof hardshell for more extreme conditions. You should also not neglect your extremities, as a large part of the heat escapes through the head and hands. Gloves, hats and neck warmers then become essential allies to retain maximum warmth.

The choice of insulation is a central element in the design of a technical down jacket . It determines not only the level of thermal performance, but also the environmental impact of the product. Natural down is often praised for its excellent warmth-to-weight ratio and high compressibility, ideal qualities for a warm down jacket . On the other hand, it loses efficiency when exposed to humidity and takes time to dry. Recycled down represents a more responsible alternative, reducing the demand for new animal resources, while maintaining similar performance—although its availability is still limited.

Synthetic wadding , usually made from polyester, retains its insulating power even when wet, dries quickly and offers better resistance to humidity - a major advantage in variable conditions. However, it is slightly less compressible than down. Recycled wadding offers the same advantages, while reducing the impact linked to the production of virgin fibers. At Lagoped , we have chosen a high-quality recycled synthetic wadding, made in Germany from recycled plastic bottles. This material allows us to design eco-responsible down jackets , high-performance, breathable and suitable for the most demanding conditions.

The thermal efficiency of a down jacket is not only based on the type of insulation used, but also on the density of its filling, expressed in grams per square meter (g/m²). This density determines the down jacket's ability to retain heat . A light weight, between 20 and 40 g/m², is ideal for mid-season jackets or intermediate layers. A medium weight (80 to 90 g/m²) corresponds to a versatile warm down jacket, suitable for most cold conditions. For extreme climates, a heavy weight (130 g/m² and above) is recommended, particularly for high mountain activities or winter expeditions.

In a technical down jacket, insulation is often distributed strategically: denser fill in the torso helps maintain warmth around vital organs, while lighter weight in the arms promotes freedom of movement and prevents overheating. This intelligent distribution also improves breathability and reduces the overall weight of the garment.

At Lagoped, we designed the HEYDO2 down jacket with 200 g/m² recycled G-LOFT® padding, a high-performance technical wadding made in Europe. The result: an eco-friendly, ultra-warm, breathable and compressible down jacket , designed for demanding environments and responsible adventurers.

The effectiveness of a down jacket depends not only on the type and weight of the insulation, but also on its structure. To improve breathability without sacrificing warmth, some technologies, such as perforated insulation, incorporate small, strategically placed openings. These perforations increase airflow and reduce moisture buildup by up to 30% , while maintaining excellent thermal insulation. This process allows perspiration to be wicked away more efficiently, thus avoiding the "sauna" effect during intense exercise.

G-LOFT®, used by Lagoped, goes even further with a spiral hollow fiber structure, inspired by the polar bear's fur. This design traps body heat while facilitating ventilation , ensuring optimal comfort. Unlike natural down, the synthetic fibers of G-LOFT® do not absorb moisture, which ensures effective insulation even in wet weather. Another major advantage: its "memory effect", which allows it to retain its loft and return to its original shape after compression, thus extending the durability and thermal efficiency of the garment.

This specific construction, combined with the right choice of weight and intelligent distribution of insulation, makes Lagoped down jackets reliable allies for facing the most demanding environments.

The CLO value is a unit of measurement that evaluates the thermal insulation of a garment based on its resistance to heat . A CLO of 1 corresponds to a level of insulation sufficient to maintain a comfortable temperature at rest in a room at 21°C. The higher the CLO value, the more insulating the garment. For example, a garment with a CLO value of 2 to 3 will provide suitable insulation for moderate physical activities in cold conditions, while a down jacket with a CLO above 3 will be suitable for extreme winter conditions. CLO values ​​are used to determine the thickness, loft, and breathability of the insulation, to choose the most suitable product depending on the climatic conditions and the type of activity.

At Lagoped, technical down jackets like the CORUJA model (CLO from 1 to 2) are perfect for physical activities, while models like the HEYDO2 (CLO higher than 3) offer optimal insulation for extreme conditions, such as during winter expeditions. The GRAND TETRAS WARM jackets and the URSK2 ski jacket are ideal for activities that combine active and static movements.

In short, choosing the ideal down jacket depends on many factors, from insulation to compressibility, moisture resistance, and lightweight. Each type of insulation has its advantages and disadvantages, and it's important to understand them to optimize comfort for the conditions you encounter. To find the perfect down jacket for your needs, one that combines performance and practicality, refer to the CLO values.

Stay warm, dry and ready to fully experience your outdoor adventures!