Adjective
insulative (comparative more insulative, superlative most insulative)
Serving to insulate
Oil is toxic when ingested and penguins' buoyancy and the insulative quality of their plumage is damaged by contact with oil. Source: Internet
Thawing of permafrost would affect the bears who traditionally den underground, and warm winters could result in den roofs collapsing or having reduced insulative value. Source: Internet