Marmot Windproof Technologies
What is windproof? A better question is; what does windproofness do?
Essentially wind takes away heat and moisture away from the body. What we experience is cooling. This sounds negative, but it can also be beneficial. At times of high aerobic activity the body will need to release more heat and moisture to cool itself. Best way – convective wind + evaporation of moisture.
Most of what we do in dressing for outdoor activities is attempt to balance heat/moisture retention and heat/moisture loss.
Here are the 5 ways we lose heat:
| Convection | air moving heat away | |
| Evaporation | moisture turning from liquid to vapor, thereby absorbing energy/heat from the body |
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| Conduction | contact with cold surfaces; sitting in the snow or holding a metal ice axe shaft |
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| Radiation | accounts for a relatively small amount of heat loss | |
| Respiration | beyond our control, unless one happens to be a Tibetan Monk |
Convection is normally controlled by the outer layers of a clothing system.
Evaporation is controlled with moisture moving base layers like DriClime and wind or waterproof shells.
Conduction is controlled by insulation and common sense.
Radiation is controlled by the clothing system in general and accounts for very little heat loss.
Respiration can be controlled by wearing something over the mouth and nose.
How is windproofness measured?
The most common method to measure windproofness or air permeability is called the Fraser-o-meter or Fraser Air Permeability Test. This measures the number of cubic feet of air that can pass thru a square foot of fabric in one minute at a pressure differential equal to 30 miles per hour wind speed. The results are given in CFM - cubic feet per minute.
Note: Air permeability and breathability are not synonymous. Breathability should be considered as Moisture Vapor Transmission and moisture can be transmitted even through non-air permeable fabrics. That said, higher air permeable fabrics are generally more breathable.
So, we know that wind will take away heat/moisture and we know how to measure windproofness. Now we have to put them together to get an idea of their affect on the user.
The different technologies today try to either balance heat retention and heat loss or maximize one side or the other. Key is to keep the body as close to its normal operating temperature of 37 degrees Celsius, as possible.
Note: moisture vapor transmission will also increase with permeability and higher wind speeds and promote cooling.
Here are some examples for reference:
| Marmot Tropo Softshell Marmot MemBrain Gore-tex |
0 cfm | Total windproofness and waterproof barrier. Needs venting to allow one to cool down faster, allowing a bit more range in colder weather without sacrificing warm weather and higher aerobic conditions. Best for conditions that are colder and wetter. |
| WindStopper Softshell | 2 cfm | Superior windproofness and excellent weather protection with some air permeability. Still needs venting to allow one to cool down faster, allowing a bit more range in colder weather without sacrificing warm weather and higher aerobic conditions. Best for conditions that are colder and wetter. |
| DriClime WindShirt | 3-8 cfm | Excellent wind resistance, can be worn almost all day in most conditions as part of a layering system. Good protection for insulation. |
| Marmot Quicksilver Softshell | 10-15 cfm | Excellent balance of wind resistance and MVT (Moisture Vapor Transmission) Wider comfort range, less need to vent. Best for activities with wide swings in activity levels and less wet conditions. |
| Malden Wind Pro | 60 cfm | Being fleece it is generally more insulating that the above. Allows for fewer stops to change layers than regular fleece. Best for colder conditions without large swings in activity levels. |
| 200 wgt Fleece | 200 cfm | High air permeability, good insulation when used with a shell, not very protective in windy conditions when used alone. Best as a layering insulation garment in colder conditions. Shown here to give an idea of the range of air permeability. |
