How to measure the breathability (r.e.t.) of a material?
The breathability of a material is its capacity to eliminate the water vapour generated through perspiration. During intense physical exercise, highly breathable clothing is therefore essential to avoid staying wet. Breathability is measured in terms of it Evaporative Thermal Resistance (R.E.T.) coefficient. It measures the resistance of a fabric to the evacuation of moisture. The lower the resistance (hence, the lower the coefficient), the more breathable the fabric!
How to choose breathable clothing
The R.E.T. is measured with a numerical index:
- RET 20: The fabric has relatively low breathability and is therefore not suitable for physical activities
- RET >40: The fabric is said to be non-breathable
You will find this information in the technical features of our product datasheets for our jacket range in particular. It is particularly important to measure the breathability of this product because, in general, the higher the waterproof rating of a garment, the less breathable it is, because of the material or coating used to stop the rain).
Another way of having a highly breathable garment, in addition to the fabric, is to choose a product with mechanical ventilation zips for regulating temperature:
In order to benefit fully from the technical properties of your clothing, you must also manage your different layers of clothing according to the level of effort you make.
(NB: some brands also use the M.V.T.R. index ."Moisture Vapour Transmission Resistance" to measure the breathability. This index measures the quantity of water that a square metre of fabric lets through in 24 hours. The higher the index, the more breathable the fabric. For example, a garment with an M.V.T.R. of 5,000 is not very breathable, whereas a garment with an M.V.T.R. of 30,000 is extremely breathable).
