One of the most significant, imminent physical transformations in home kitchens will come from an unlikely source: the refrigerator. Whirlpool Corporation recently unveiled SlimTech, which it claims is “the first vacuum insulated structure technology in a refrigerator in the North American market,” transforming this traditionally prodigious box into a much thinner appliance.
Vacuum Insulation Panels (VIPs) consist of compressed micro-porous powders encapsulated within a reflective, high-barrier film. They are dramatically more effective than conventional insulation. In refrigerators, the novel material allows a 60% reduction in door thickness compared with typical polyurethane foam, allowing a 25% increase in overall interior volume and up to a 50% reduction in energy consumption.
Although VIP technology dates back to 1930, the insulation has thus far been used primarily in small-scale, controlled applications (such as transporting COVID-19 vaccines) due to its high cost. That said, Whirlpool’s contribution marks a milestone in scale and consumer accessibility. And as concerns about increased climate volatility and energy demands continue to grow, buildings are the next obvious target for VIP applications.
Kingspan offers a VIP product called OPTIM-R, an ultra-thin insulation that exhibits an impressive five-times performance gain over conventional alternatives. The airtight panel, comprised of a microporous core sealed within a reflective envelope, offers R-28 per inch. (By comparison, compressed fiberglass batt insulation provides an R-value of about 4 per inch). Given the high cost of VIP technology, which can be as much as $10-12 per square foot, ideal applications include space-constrained adaptive reuse projects. Terraces and balconies may also be insulated without creating significant elevation differences between the interior and exterior.
Elevate manufactures VIPs designed especially for commercial roofs. The system consists of Panasonic Advanc-R VIP technology, foam adhesives, and protective Isogard HD boards installed above and below the insulation. The 2’ x 2’ or 2’ x 4’ panels contain a microporous glass fiber matrix and boast an R-value of 66 at a mere 2-inch thickness for the whole system. Advanc-R VIPs exhibit a Class A rating for fire and smoke and weigh only 1.4 pounds per square foot. The Elevate system is advantageous in situations where roofing height constraints are limited or maximizing available interior height is essential.
In addition to energy performance considerations, VIP technology continues to improve in other areas of environmental sustainability, such as the embodied carbon of the material components. The fumed silica comprising the core is typically heated at 3,000°C, requiring significant processing energy. Harjit Singh, an engineer at Brunel University London, has devised an alternative VIP core material using perlite—the volcanic glass typically used for horticultural purposes. Perlite is processed at a much lower 1,000°C and is widely available commercially. Additionally, Singh’s perlite-based prototype encapsulates the core within a plaster-coated mesh, providing enhanced protection over the metalized PET used with most VIPs. Other advances include the development of improved recycling techniques and the elimination of harmful refrigerants and fire retardants.
Despite their impressive thermal performance, VIPs present challenges for building construction applications. The relatively high cost mentioned previously limits VIP use in projects without severe space limitations. VIPs are also vulnerable to damage, as a single puncture in the outer surface compromises the vacuum and reduces the panels’ insulating capacity. Furthermore, VIP performance gradually degrades over time, and the long-term viability of the material will require further study.
Nevertheless, VIPs' remarkable operating energy and space-saving contributions cannot be ignored. Impressively, a comprehensive study in Energy and Buildings estimates that the carbon reduction requirements of the Kyoto Protocol would be readily achieved “if every non-insulated building currently existing in the European Union is insulated with a layer of only 2 cm thick VIPs.” Given their extraordinary properties, VIPs may eventually disrupt the building insulation market, making facades thinner, spaces more voluminous, and buildings less energy-intensive.
