Despite the fact that we are now living in the 21st century, aerogel insulation seems like a material out of science-fiction. It is the lightest solid known, although by volume it is 99% air. It is breathable, but it doesn't absorb water. It is incredibly strong for its weight. But most importantly, it is a fantastic insulator.
Some specialty insulation companies are now producing aerogel products that can be used for building insulation, although the largest market for the material is still in industry. Aerogel insulation is also exciting because it provides good benefit with a thin profile. For instance, shipping-containers, which have a narrow width to begin with, can be insulated without giving up too much valuable space to attaching insulation to the walls.
A couple products are now available on the market, although their use is still constrained because of the relatively high cost of the material. Aspen Aerogels makes an aerogel blanket called Spaceloft, and Thermablok produces narrow strips of aerogel that may be a more cost-effective way of utilizing aerogel insulation without breaking the bank.
Aerogel is such a good insulator that a blowtorch on one side cannot light a match on the opposite side. While that is an extreme case, it demonstrates the effectiveness of the material. (And if you are a numbers geek, a typical aerogel insulation blanket has a thermal conductivity of 0.091 BTU-in/hr-sq.ft.-F at an ambient temperature of 32 degrees Fahrenheit, corresponding to an R-value of more than R-10 per inch. That's nearly double the insulation value of the best rigid insulation boards currently available.)
Aspen Aerogels' Spaceloft Insulation, is a 57-inch wide roll of aerogel material available in 0.20 in. and 0.40 in. thickness. Spaceloft is a useful product for insulating existing walls in retrofit situations where it is important to minimize the amount of floor area lost to building up wall insulation. An old brick building can be a beautiful thing, but brick makes a poor insulator. Instead of building a new insulated wall against the existing wall that would be 4" thick (or more), a Spaceloft blanket covered by drywall can achieve similar energy-efficiency in a wall covering that is less than an inch thick.
According to Martin LaMonica of CNET, Spaceloft blankets have been used by the Rhode Island Housing Authority to retrofit a 50-unit housing complex that was built with no insulation in the 1940s.
Thermablok manufactures aerogel in 1-1/2" wide strips rather than broad sheets. In stud wall construction, the cavity between the studs is filled with insulation, but the studs themselves can conduct heat and cold, a process known as "thermal bridging," which reduces the thermal performance of the wall. By covering the studs with strips of aerogel insulation before the interior drywall or exterior sheathing is applied, the thermal bridging is broken, and the thermal performance of the wall can increase by 30% or more. This can be an efficient use of aerogel material in a cost-effective way.
Thermablok strips can be installed on the exterior of the studs during new construction, or can be applied on the interior during remodeling as well as new construction. This makes it suitable for energy efficiency retrofits. As with Spaceloft blankets, because Thermablok is so thin (about 1/4" once installed), it can be used to improve performance without taking away great amounts of space from inside the building.
Thermablok strips have been used in the Solar Decathlon house from the California College of the Arts and the University of Santa Clara, California (also known as the Refract House shown above). Suggested retail price for Thermablok tape is $1.99/ft.
Photo credits: Thermablok, Aspen Aerogels, DOE.