Glass wool or hemp fibers

I am currently facing the decision of which insulation material to use for converting the attic. Hemp fibers appeal to me from an ecological point of view, but I have read that glass wool is supposed to insulate better. On the other hand, the manufacturer of the hemp fibers claims that their product protects better against heat in summer. The glass wool has a WLG of 32, the hemp fibers only 40. Actually, I am especially concerned about heat protection, and I would even accept compromises in insulation for that. But is it really true that hemp fibers provide better heat protection?

Hemp fibers are heavier than mineral fibers, so they store (relatively) more heat, which is transferred more slowly to the interior rooms in summer. The same applies to wood fiber insulation materials.

Aha, so the hemp fibers really do provide better heat protection. It is really important to me that it is no longer so scorching hot under the roof in summer, so I will choose the hemp fibers. Thanks for the info :)

In addition to the hemp fibers, a roof sheathing made of wood fiber insulation would also be advisable (also for summer heat protection); it is available hydrophobized, so that the construction site can withstand a few rainy days with an uncovered roof.