As parts of the United States experience life-threatening temperatures, the first, most effective line of defense may be a thin layer of rigid foam between your home and the sun.

Unless you’re a building scientist, you probably don’t think about home Insulation much. Or you didn’t think about it until temperatures started to hit triple digits in the United States for a week at a time. Now, along with purchasing air conditioners, you’re probably looking at upgrading your insulation, replacing some old windows, finishing a bedroom in the basement (where air stays cooler), or moving to a cooler climate.