High Performance Thermal Insulation: Silica Aerogels in Construction Technology

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 a remarkably low density and 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 fibrous blankets containing aerogel. These blankets are typically made using low temperature supercritical drying with CO2, a process that takes days to complete. Union College uses 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 an 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 the hot disk method 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). When applied to the exterior of studs in a typical New England home the application of silica aerogel insulation could result in 483 to 855 fewer kilograms of carbon dioxide being released into the atmosphere annually. A mock building was designed, constructed, and outfitted with an aerogel window and insulation to demonstrate the practicality and the energy savings afforded by the use of aerogels in construction. This report will cover the fabrication of an aerogel blanket as well analytical and experimental methods used to quantify the benefits of aerogel insulation