Straight Green : New Use for Old Sciences
January 3, 2012
By now, most people have heard or read about the solar panel company Solyndra and its spectacular descent into bankruptcy, taking with it a massive $535 million federal guaranteed loan. Following closely on Solyndra’s heels, Michigan-based Evergreen Solar Inc. also filed for bankruptcy, costing taxpayers millions of dollars in loans resulting in the loss of more than 800 jobs and shuttering a taxpayer-assisted $450 million manufacturing facility.
Not all federal giveaways have ended so badly. Last year, the Department of Energy gave $76 million from the American Recovery and Reinvestment Act to 58 building efficiency projects. Of these, Dow Corning received $1.24 million to develop a better insulating material for EIFS. I was given a preview of this new material shortly after Dow Corning received the grant and was asked to provide comments and observations on the early ideas that had been generated by Dow Corning in the development of the new product, which Dow Corning calls a Vacuum Insulation Panel or VIP.
A year after I was first introduced to this new product, Dow Corning has settled on its final form and integration into the building enclosure, offering some very exciting possibilities to greatly increase the energy efficiency of buildings.
WHAT IS A VIP?
In 1882, a Scottish scientist named James Dewar invented the vacuum flask, a double walled, metal-coated glass bottle with the air sucked out of the space between, to be used to store liquid gases and keep them cold. It turns out that the vacuum, combined with the metal coating, is a very efficient way to control heat transfer. Thermos took advantage of Dewar’s unpatented invention and is still making Thermos bottles today, more than 100 years later.
Vacuum Insulation Panels share the same physics as the vacuum flask but are made with slightly different materials. The core of a VIP is made of a porous material, like glass fibers or silica, and then wrapped in a metallic or mylar film which is then vacuumed and sealed. Developed commercially for use in refrigeration equipment, they are not new to the world, but they are new to the building industry. The first VIP-lined fridge was offered for sale in 1997 by Sanyo. VIPs pack a tremendous amount of insulating value in a very compact space, something the refrigerator/freezer industry has capitalized on in producing fridges and freezers that use significantly less energy while simultaneously providing more storage area.
The Achilles’ heel of VIPs is also the greatest challenge that companies face in their race to develop VIPs for use in buildings; vulnerability to puncture. If a VIP loses its vacuum, the insulating value is reduced to a fraction of what it was. Researchers at Dow Corning think they have solved this problem in developing a sort of hybrid insulating panel using a sister product, Styrofoam, as a protective jacket enveloping a 1-inch VIP, snugly nestled in the middle of the 2-inch thick board insulation. Dow Corning calculates a total R value of 30 for this hybrid board insulation, reduced from the R-40 value of the VIP due to thermal bridging at the edges of the VIP.
The Dow Corning panels are designed to be fastened only at the edges, allowing the field of the panels (and the VIPs) to remain free of penetrations. This system has been developed for both EIFS and rainscreen cladding, the latter using a proprietary secondary support system attached to the backup wall at the panel edges. The rainscreen system is designed to accommodate a large range of cladding materials including metal wall panels, composite metal panels, wood siding and fiber cement siding.
There are other exterior enclosure assemblies that seem like a perfect fit for VIPs, taking full advantage of the high insulating value while offering protection from damage-spandrel panels in curtain wall assemblies for example. Instead of being limited to R 4 per inch mineral fiber insulation within the mullion depth, VIPs could easily be used instead (or in combination) to achieve an R value of 40 to 80. Curtain wall shadow boxes are also an obvious match. VIPs have also successfully been incorporated into precast concrete sandwich panels and cross laminated timber wall panels in Germany. VIPs have also been used in flooring underlayment and in roofing assemblies. Once protection of the VIPs is considered, there is virtually no end to the possibilities of their use in the enclosure.
Other Important Considerations
Cost: Currently, VIPs cost $5 to $10 per square foot. Design teams that are interested in incorporating this material into the enclosure will have to carefully evaluate the cost for the panels and the associated benefits and offsets. About $10 dollars a square foot may be within reason if the need for even more expensive and exotic enclosure systems like triple paned glazing, double low-e coatings and ultra-high performance curtain wall framing can be eliminated. Dow Corning expects that its current price of $10 per square foot can be reduced to something closer to $6 per square foot for orders exceeding 5,000 square feet.
Size: VIPs are currently available in sizes no bigger than about three feet in either direction. Dow Corning’s VIP comes in a 2-foot-by- 3-foot size. The good news is that the panels can be made to nearly any configuration within the available size. Square, rectangular, L-shapes, T-shapes-anything is possible. Non-standard shapes and sizes also increase price per square foot, however.
R Value Warranty: Dow Corning predicts that its VIP will retain 80 percent of its insulating value 25 years after manufacture. For a 1-inch thick panel at R 40, this works out to be R 32 at 25 years which is still many times more than any other type of insulation. In the event that the panel is punctured and the vacuum is lost, Dow Corning states that the R value of its VIPs will maintain R 7 per inch. Because this is an experimental product, however, Dow Corning does not stand behind this in any way. The product data sheet states:
“VIP is provided as is, with all faults and without warranty of any kind, either express or implied, including but not limited to, the implied warranties of merchantability and fitness for a particular purpose.”
MORE VIPS COMING TO NORTH AMERICAN MARKET
Dow Corning is not the only company that is pursuing a VIP product for the commercial building industry in North America. Panasonic also offers a VIP with an R value of 30 per inch and has successfully installed the panels in a demonstration project, a 3,500 square foot, three-bedroom residence called Harmony House in Burnaby, British Columbia Canada. The home uses VIPs in the wood framed walls, protectively sandwiched between rigid insulation board and spray applied polyurethane foam insulation within the stud cavity spaces. This yields a whole wall insulating value of R 37.7, taking into account the thermal bridging at the studs.
R-Box LLC is a North Carolina based company that will be offering a unique product that uses VIPs-The Insulated Electrical Box, or EBOX for short. These insulated electrical boxes have a VIP at the back of the box that is installed flush against the exterior wall sheathing, greatly reducing the heat loss through the box to the exterior. The dimension of the VIP is larger than the box which creates a sort of flange that the cavity insulation overlaps, resulting in a continuous plane of insulation, no longer rendered discontinuous by an un-insulated electrical box.
VIPs seem positioned to take a prominent place in the construction industry as a super-insulator used to dramatically increase buildings energy efficiency. As national and regional energy codes become more and more stringent, materials like VIPs will be paramount to designers to solve the problem of how to meet these new energy code requirements. While the cost of these panels seems high a first glance, they can offset costs for other, more exotic strategies for meeting energy code requirements such as triple paned glazing, double low-e coated glazing and ultra-high-performance glazed framing systems. As designers and manufacturers develop more ways to use the panels and increase their applicability, Dow Corning is convinced that the cost will come down and maximum panel size will go up. It looks like the federal government got one right, this time, and that their grant to Dow Corning has resulted in a viable, innovative product that has the potential to save taxpayers millions and millions of dollars in buildings energy use.