Does Humidity Affect the Thermal Properties of Mylar Bivys?

Effects of Humidity on Mylar Bivys

Mylar bivys are designed to be waterproof and windproof, but high humidity can compromise their thermal performance. When warm, moist air comes into contact with the Mylar material, it can lead to condensation, which reduces the material’s insulating R-value. This condensation can also lead to a buildup of frost or ice, further reducing the bivy’s thermal performance.

Measuring the Impact of Humidity on Mylar Bivys

Studies have shown that a 50% relative humidity can reduce the R-value of Mylar by up to 20%. To mitigate this effect, it’s essential to maintain a dry environment inside the bivy. This can be achieved by using a waterproof and breathable layer, such as a silnylon or eVent fabric, as the outer layer of the bivy. A well-ventilated bivy design can also help to reduce condensation and maintain a dry environment.

Techniques for Improving Thermal Performance in High Humidity

To improve the thermal performance of Mylar bivys in high humidity conditions, consider the following techniques: (1) use a breathable and waterproof outer layer, (2) design a well-ventilated bivy to reduce condensation, and (3) use a moisture-wicking layer, such as a silk or merino wool liner, to maintain a dry environment. By implementing these techniques, you can minimize the impact of humidity on the thermal properties of your Mylar bivy.