Outlook for "Smart" Windows Appears
Better than Ever
- New materials and processes will finally make large,
variable-tint windows affordable.
- Energy use could drop by 30 to 40 percent in some
buildings, potentially saving the nation billions of dollars.
- The technology is robust and durable, independent
tests show, and commercialization is under way.
Substantial savings in energy costs and a new multibillion-dollar industry are in the
nation's future as a result of a joint research venture that developed innovative
materials and processes for making affordable windows that tint at the push of a button.
With co-funding from NIST's Advanced Technology Program (ATP), SAGE Electrochromics, Inc.,
teamed with 3M Co. and the Center for Ceramic Research at Rutgers University to develop
new electrochromic (EC) technology--coatings that control the transmission of light, heat,
and near-infrared radiation--and demonstrate the largest all-ceramic EC "smart"
windows ever made. In the early 1990s, SAGE patented an EC system consisting of five
layers of ceramic thin films, but the company's only product was a laboratory curiosity--a
2-inch-square sample--and device performance was not well understood. By joining forces in
the three-year ATP project, which ended in 1997, the partners developed EC technologies
for use on both glass and plastic.
The ATP project enabled researchers to design and deposit EC materials in a way that
eliminated hazardous and expensive materials, switch to a lower cost processing method
that balanced electrical, optical, and other properties to make a large-area light valve
device, and make several 1 x 1-foot demonstration windows. Tests by the National Renewable
Energy Laboratory show that the prototype windows are robust, durable, and maintain a
contrast ratio that meets Department of Energy (DOE) guidelines for energy-conserving
windows. SAGE has received follow-on contracts from DOE and other sources to scale up its
manufacturing process and signed an agreement with Apogee Enterprises, Inc., a large
Minnesota company with subsidiaries in the glass and coating businesses, to scale up and
market "smart" windows. SAGE predicts that its EC windows eventually can be sold
profitably for $10 per square foot wholesale, enabling retail buyers to recover the
additional investment beyond the cost of conventional windows within three years. Studies
by Lawrence Berkeley National Laboratory suggest that EC windows could save about
one-third of the energy used in some office buildings and that use of the latest
energy-efficient technologies in replacement windows and new U.S. residential construction
could save perhaps $5 billion annually. Future EC applications range from highway signs to
eyewear to aircraft windows.
ATP funding: $3,483,000
Non-ATP funding: $3,699,000
For more information
May 1999
|
