System of clothing

Heat loss

We use functional outdoor clothing to be able to influence our body heat loss. It depends on the activity we are doing and on the environment where we are doing it. To feel comfortable in all circumstances, it is necessary to choose clothing suitable for various external conditions and various levels of exertion. During outdoor activities our comfort in terms of heat loss is influenced mostly by three sources: water (in various states), wind, and our own perspiration.

Waterproof qualities

It does not matter whether it is raining or snowing, the critical factor is that our clothing does not get soaked. In wet clothing our body loses heat 32 times faster. This is called wet conductive heat loss. And the con- clusion? Functional outdoor clothing must be waterproof. In accordance with ISO 811 standard a material is waterproof when it resists the pressure of 1,3 meter water column. During various outdoor activities the pressure is very often several times higher (sitting on the snow, pressure of a backpack strap on the back). The minimum value for practical usage of a given material during outdoor activities is thus a 20 meter water column.

Windproofness

Wind - or convective heat loss - is also a critical factor in heat management. Iťs importance can be seen in the so called wind-chill effect. Put simply: the stronger wind is, colder we feel. This shows that functional outdoor clothing must be windproof.

Wind:	Outer temperature:
	12 °C	10 °C	8 °C	6 °C	4 °C	2 °C	0 °C	-2 °C	-4 °C	-6 °C	-8 °C	-10 °C	-12 °C
	Colder we feel:
10 km/h	10 °C	8 °C	5 °C	3 °C	1 °C	-1 °C	-4 °C	-6 °C	-8 °C	-10 °C	-12 °C	-15 °C	-17 °C
20 km/h	6 °C	3 °C	1 °C	-2 °C	-5 °C	-7 °C	-10 °C	-12 °C	-15 °C	-17 °C	-20 °C	-23 °C	-25 °C
30 km/h	3 °C	1 °C	-2 °	-5 °C	-8 °C	-11 °C	-14 °C	-16 °C	-19 °C	-22 °C	-25 °C	-28 °C	-30 °C
40 km/h	2 °C	-1 °C	-4 °C	-7 °C	-10 °C	-13 °C	-16 °C	-19 °C	-22 °C	-25 °C	-28 °C	-31 °C	-34 °C

Breathability

Whatever we wear we will always perspire. This is how our body regulates iťs temperature. It is important that this perspiration does not collect on the inner side of our clothing, but that it diffuses freely. This is why functional outdoor clothing must be breathable. Under the term breathability we understand a rate of moisture vapour transmission. The most objective comparative method is method R_et value of the given material, which represents the material resistance towards moisture vapour transmission in m².Pa.W^-1 units. For simplification the following table can be used:

m².Pa.W^-1	Breathability
0 - 6	very good
6 - 13	good
13 - 20	satisfactory
20 - 30	unsatisfactory

Light weight. Durability. Top-quality style.

Functional outdoor clothing must be waterproof, windproof and at the same time breathable. It is about maximal functionality in various weather conditions and under various levels of exertion. Of course, we cannot forget light weight, durability, top-quality style, fashionable appearance, and many practical details.

Layering system of clothing

If we want to feel comfortable during our outdoor activities, we must wear appropriate clothing. The clothing which is suitable for the intended level of exertion and the expected weather. At the same time we should remember that it is necessary to change the system of clothing (add or take away its separate layers) according to weather changes or intensity of activity. Modern functional clothing systems usually consist of three layers, which jointly resist weather conditions, regulate heat transmission, and allow our body to stay comfortable.

Absorption layer - The absorption layer transmits moisture in liquid state, i.e. perspiration, away from the body. It is made of synthetic non-absorbent fibres and is in direct contact with the skin.
Insulation layer - The insulation layer reduces heat loss and is at the same time breathable, so that water vapour condensation does not occur. In some cases it also functions also as a top layer; in these cases more emphasis is put on its windproofness and water resistent qualities.
Top layer - The waterproof qualities of the top layer protest against unfavourable weather conditions (rain, snow, etc.). The top layer is also breathable and therefore protects the interior layers against the accumulation of moisture. It also provides sufficient wind protection.

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