High Performance Thermal Insulation: Silica Aerogels in Construction Technology

Earths average surface temperature has risen 1.1 °C since 1880, with roughly two thirds of this warming occurring since 1975. Despite progress in the global production of renewable energy technology the transition is not happening fast enough; currently renewable resources supply only about 19.3% of the total world energy demand. The United States is a world leader in the production and expenditure of energy, accounting for 18% of the total global energy consumption in 2016, 40% of which was used for the heating, cooling, and lighting of commercial and residential buildings. Currently, traditional air-based insulation products are being used in thicker and more numerous layers in an attempt to keep up with contemporary codes and standards. One promising alternative to traditional insulation is silica aerogel. With an extremely low density and a remarkably small thermal conductivity, silica aerogel could save energy, space, and weight in new and retrofit structures. Silica aerogels are currently most widely used in the construction industry in the form of a fibrous blanket embedded in aerogel. These blankets are typically made using low temperature supercritical drying with CO₂, a process that takes days to complete. At Union College we use a patented process known as Rapid Supercritical Extraction (RSCE) where the precursor solution is poured into a mold and subjected to high temperatures and pressure via a hot press to achieve a supercritical state and create aerogel. This process results in an aerogel in a few hours. The focus of this project was on making aerogel blankets using the RSCE method and comparing them to commercially available products. Specimens were made using both rock wool and quartz felt as the fibrous batting. The thermal conductivity of each sample was measured using a hot disk system and their flammability was quantified by a vertical burn bench test. The thermal conductivity of the commercial, quartz felt, and rock wool blankets were found to be 0.035, 0.037, and 0.046 W/mK respectively, less than or comparable to that of commercial fiberglass insulation (0.045 W/mK). A mock building was designed and constructed  to demonstrate the practicality and the energy savings afforded by the use of aerogels in construction.