>>2793779Think about it. When you sweat, it means you're hot. If you're hot, your sweat needs to cool you down by evaporating close to your body. It can do that best if you're wearing something really close to your body, or nothing at all (unless you're sweating so much it is literally dropping down from you). Well, a mesh shirt is the closest thing you can do to wearing nothing next to your body while still wearing clothes.
>InsulationYou can wear insulation above your mesh. In fact, brynje makes clothes that are mesh on the inside, merino jersey just above the mesh on the outside. It traps little air pockets next to your body, which makes the total insulation higher than just the merino jersey (though lower than two merino jerseys over each other). Since mesh is light, it is still decently effective on a per-weight basis, though not as effective on a per-bulk basis. Which doesn't matter much because the bulk of a mesh shirt is minimal. Just know that you cannot replace a jersey with a mesh and expect the same warmth, especially not if you're not wearing something close-fitting above it.
