It depends on several factors as far as material weight, yardage, and type of material. A kilt made with a lighter weight material or less yardage can feel cooler as it is less insulating. More layers (added my pleating with more yards of material) will normally add more insulation then a heavier material. Simply put: If you are choosing between a 16 oz 5 yard kilt or a 13 oz 8 yard kilt the 16 oz will most likely feel cooler yet not as cool as a 13 oz 5 yard kilt. As I understand it, wool wicks away moisture better then PV, so some people will feel cooler in wool while others will feel cooler in PV. There is no best answer for everyone when looking for the best kilt to stay cool in during hot weather as there are a lot of personal and climate factors involved.