Aspen Aerogels, which makes insulating material for industrial applications, has started selling its air-filled aerogel blankets to make existing buildings more energy efficient. Aerogels are made by removing the liquid from gels, resulting in a material that is more than 90 percent air. The porous structure of that nanomaterial makes it difficult for heat to pass through. As a result, aerogels make very good and light-weight insulators. Aspen Aeorgels says that its Spaceloft blankets have two to four times the insulating value per inch compared to fiberglass or foam. It's also relatively easy to work with, allows water vapor to pass through, and is fire resistant. The product is more expensive than alternatives upfront, but it makes sense in certain cases such as masonry, curved walls and walls that don't have a cavity typically formed by wood framing that can be filled.
