Vacuum-Insulated Panel (VIP)
According to Arizona Roofing Systems, the best roof repair company in Mesa, AZ, VIPs are thermal insulators made up of a gas-tight enclosure surrounding a rigid core, from which a qualified person has expelled the air.
Membrane walls: They prevent air from entering the panel;
Panel: Consists of a rigid, highly porous material -fumed silica, aerogel, perlite, or glass fiber -to support the membrane walls against atmospheric pressure after expelling the air.
Chemicals: Known as getters, they collect gases leaked through the membrane or off-gassed from the membrane materials.
The “hardness” of a vacuum
The vacuum’s pressure, or its “hardness,” is its essential property. We often measure that with Torr units. One Torr is exactly 1/760th of a standard atmosphere (1.3 x 10-3 atm), or approximately 1 mm of mercury.
A very hard vacuum expels more of the air molecules, leading to a greater negative pressure. The walls of a typical Stanley Thermos bottle contain a relatively hard vacuum of 10-6 Torr. The hard vacuum enables it to keep coffee hot all day. The force in a flat vacuum insulation panel is typically no more than 1/1000th as strong (10-3 Torr).
The harder the force, the more difficult it is to maintain it. Manufacturers make Thermos bottles with a circular design for optimal strength. With flat panels, it is hard to achieve comparable strength and maintain such a hard vacuum, particularly at the edges.
Using vacuum to insulate our houses
Vacuum insulation panels are useful in protecting some high-tech demonstration homes, such as entrants in the Solar Decathlon Student Design competition. The high cost makes them impractical for real buildings.
There is also another issue – puncturing that vacuum insulation panel will significantly reduce its insulating performance.
Manufacturers first used vacuum insulated panels in commercial applications such as refrigerators, freezers, and cold shipping boxes. VIPs have lately appeared in building applications as regulations that are more stringent have come into place.
The US Department of Housing and Urban Development carried a research on the market potential of VIPs in residential buildings. The study concluded that VIPs had become a ‘feasible and important’ means for designing energy efficient buildings. Kingspan Insulation launched OPTIM-R™ in 2012.
They offer very efficient insulation (achieving an R-value of 50) within a very slim profile, making them useful on roofs where adding bulk is costly. Researchers found that VIPs were robust if installed with care and that R-50 insulation can offer favorable payback in one-story buildings in regions with extreme climates and high utility costs.
They are ideal for the transportation of heat sensitive products and insulation of residential and commercial appliances since they have low thermal conductivity (increased R-Value), improved product life, and an environmentally sound construction.
VIPs are also a thin and lightweight alternative to the bulk created by conventional insulation materials.
How VIP works
Heat transfer can occur from conduction, convection, or radiation. VIPs consist of an evacuated nonporous or fibrous core material sealed off with an impermeable enclosure, which results in a thermal conductivity that is lower than conventional insulations.
Since the vacuum creates an atmosphere with hardly any molecules, it becomes harder for heat to spread into the space, making heat transfer to surrounding molecules nearly impossible.
Without the presence of gas in the vacuum insulation panel, heat transfer by convection currents also cannot occur. Heat loss through radiation is also important to consider, as there is no way you can completely prevent heat loss. However, the highly reflective coating of the VIP can avoid a significant loss of heat. Panasonic’s Vacuum Insulation Panels have a thermal conductivity value of about 0.0018 W/mK.
Why not use conventional foam insulation
Standard foam insulation can be as much as 20 times less efficient than Panasonic’s VIP. Traditional insulations have a much lower R-value than vacuum insulation panels and bring with them a host of environmental concerns. Urethane foam, for example, contains several harmful chemicals and can be very toxic if exposed to high amounts. Panasonic’s Vacuum Insulation Panels are composed of 75% recycled material, are completely recyclable, have a low Global Warming Potential (GWP), and are RoHS compliant. Furthermore, according to Arizona Roofing Systems, a roofing company in Mesa, Arizona, they do not off-gas at all, making them an overall greener option for thermal insulation.