If there's a Superman of home insulation, it's aerogel. It has an R-value of R-10.3 per inch of thickness [source: Meinhold]. So what makes aerogel so super? In a word, air. Chemical engineer Samuel Stephens Kistler first invented aerogel in 1931. According to legend, Kistler made a bet with a friend that he could replace the liquid in a jelly jar without causing the jelly to shrink. Kistler won the bet. So how'd he do it? He removed the liquid and replaced it with air [source: Meinhold].
Today, scientists make aerogel by removing the liquid from silica under high pressure and temperature. What's left is a material that is very light and more than 90 percent air. Aerogel's molecular structure makes it difficult for heat to pass through [source: Nusca]. As insulation, aerogel comes in sheets that can easily be tacked on to the studs in a wall. In fact one type of aerogel, ThermaBlok, has a peal and stick backing for easy installation [source: Thermablok]. Aerogel insulation is very expensive, though, and sells for up to $2 a foot [source: Meinhold].