Outdoor clothing breathability - Is it all hype?
Breathability - The Spin
- Purchasing performance outdoor clothing can be mystifying.
- All brands claim to be the best.
- The buzzword is breathability, which is used time and time again.
- Numerous brands trying to outdo the others with the “best” breathability.
But what do they mean by breathability and how do they measure breathability in real world conditions?
The Test Standard For Breathability
The rate of breathability quoted is normally the rate, which is
measured by the ISO11092 test standard. This was devised to measure the rate
by which moisture vapour moved from the inside to the outside of a fabric.
The parameters of this test are not realistic!
In simple terms the test is like wearing your waterproof breathable jacket
in 35°C (93F) outside temperature and NO RAIN! That is equivalent to
the Sahara Desert. These conditions are not REALISTIC to what weather we
experience in the Western Hemisphere.
So why measure under these conditions?
A few members in the fabric industry to fit their products formulated it. In
these conditions, the test results prove favourable to one particular brand
of fabric, which is then able to claim to be the most breathable on the market.
Correct but only in hot and dry conditions.
The Science
WHY DO BREATHABLE FABRICS NOT WORK? – It is because of
the formation of Dew or Cold bridging that occurs when there is a differential
in temperatures. In plain language this is “CONDENSATION”.
Condensation forms inside waterproof and so called breathable garments
when it rains or the outside temperature is lower than the inside.
The average temperature in the western hemisphere is between 10-12°C
(50F and 52F) and can fall lower when it rains. Compare this to a car windscreen
on a cold morning or when it rains, condensation forms on the inside of the
car and the glass has to be force ventilated. Those that wear spectacles
understand this well.
Leeds University:
Research by Leeds University proves conclusively that all single layer waterproof/breathable fabrics stop working after one hour of use in wet and cold conditions the realistic conditions when a waterproof is required to work. The current industry testing standards for breathable waterproof fabrics emulates the Sahara Desert rather than wet conditions.
Conclusion
All breathable waterproof materials stop breathing after only 60 minutes in rain and wet conditions. So if you only pay £80.00 for a single fabric outer jacket, you will probably be quite satisfied. However if you have paid £150 or more then you will have a garment that works no better than the cheaper one in wet conditions.
Single layer breathable fabric garments do not work in cold and wet conditions.
Only the use of a dual layer system of garment construction can work in these conditions. Check out the superb Keela range to see how this works in action.
