Wool’s Dynamic Breathability Revealed

A new scientific study confirms that 100% wool base-layer garments provide greater thermal comfort for outdoor ‘stop-go’ sports including hiking, cycling and rock climbing in both activity and rest phases. Wool’s unique natural structure allows the fibre to react to changes in body temperature, ensuring the wearer maintains an optimal microclimate in dynamic environments.

Until recently, only anecdotal evidence has long argued that wool base-layers are more comfortable for high intensity stop-go sports, before, during and after exercise, compared to base layers of made of other fibres. However, a three-year PhD study undertaken at North Carolina State University now validates this unique benefit of wool’s superior thermal comfort as unmatched by fabrics of non-wool fibre compositions of similar thickness and weight.

The solution is to select clothes that enable the body to maintain stable thermal comfort. Wool’s natural thermoregulatory capabilities makes it the ideal fibre to create a buffer between fabric and skin, insulating athletes against cold and releasing heat through the wool fibre’s breathable structure.

The combination of wool’s ability to absorb moisture, generate heat and then only gradually release that moisture, together with its hydrophobic outer layer deferring rapid evaporation and cooling, were concluded to be responsible for wool’s dominance.

- Angus Ireland, AWI Program Manager, Fibre Advocacy & Eco Credentials

Study proves wool’s superiority during resting phases

Garments tested as part of the study included 100% wool, cotton, viscose and polyester of similar fabric weight and thickness. To investigate the robustness of the study, each fabric was tested using ‘sweating manikins’, and then humans.

The sweating manikin study demonstrated that wool has the highest capacity to support the transition from an environment of 45% relative humidity to 80% humidity, with efficiency surpassing that of viscose, cotton and polyester. With the ability of the fabric to breathe and dry quickly, the study demonstrates the premier natural capabilities of wool to maintain enhanced comfort and thermal sensation, in comparison to other fabrics tested.

Figure 1 demonstrates that wool garments maintain greater thermal sensation during the resting phase.

Further developments by the North Carolina State University researchers involve modified laboratory equipment generally used by outdoor clothing designers to measure the thermal comfort of fabric, to show the dynamic phases of activity and rest experienced by athletes in stop-go sports including hiking, cycling and rock climbing.

When wearing wool, athletes maintain thermal comfort and retain more energy to use during their sport and competition. Ongoing research aims to identify the scale of this effect and its relevance to athletes.