Alpen High Performance Products Inc., a Colorado-based, longtime manufacturer of commercial and residential ultra high performance windows, announced that the U.S. General Services Administration (GSA) has finalized and published the results of its nearly year-long testing and evaluation of quad-pane windows manufactured by Alpen. The windows were tested and evaluated as part of GSA’s Green Proving Ground (GPG) program, which uses GSA’s real-estate portfolio to evaluate innovative and high-potential, sustainable building technologies that reduce energy in federal buildings.
Double-pane windows have been the industry standard for the last several decades in federal buildings. Until now, windows with R-values of 5 or greater have been made with triple panes of standard glass, making them typically thicker, heavier and substantially more expensive than traditional dual pane window units. The use of thin glass, similar in thickness to that used in flat screen televisions, or suspended film as the center pane(s) can significantly reduce overall window weight and structural requirements.
The U.S. Department of Energy’s National Renewable Energy Laboratory evaluated Alpen’s quad-pane windows at GSA’s Denver Federal Center Building 41 in Denver. For this study, Alpen’s high performance quad-pane windows (half quad-pane windows with suspended film and half quad-pane windows with thin glass center panes that are four to six times lighter than typical glass used in traditional triple pane glass units) were installed in the building, all with super-insulating fiberglass frames. Researchers measured glass and frame surfaces to compare and calibrate measurements with models created using Lawrence Berkeley National Laboratory’s WINDOW and THERM software. The modeling was measured against high-performance double-paned windows that employ a standard low-emissivity glass coating.
The report measured the incremental cost difference between Alpen’s high performance quad-pane solutions and a high performance dual-pane, aluminum-framed window. The quad-pane windows reported an average simple payback of only 1.8 years—substantially below the success metric of less than 15 years. For new construction and window replacements, the quad-pane windows have payback between one and six years, depending on climate zone and utility rates.
The testing showed significant expected reductions in HVAC loads in buildings using the quad-pane windows, ranging from 19 to 33 percent depending on climate zone. GSA determined that the quad-pane windows provide significant energy savings and are cost effective due to their superior thermal performance. Where weight was a concern for triple- and quad-pane windows using standard glass thickness, the report concluded that both configurations of Alpen’s quad-pane windows have the same form factor and a comparable weight as a standard double-pane window but with an average of 24 percent more energy savings.
The quad-pane windows are versatile in that they are suitable for fixed, non-openable as well as operable windows, with ultra-slim, modern profiles that work well with contemporary and commercial aesthetics. They are suitable for new construction as well as retrofits and replacements for residential, commercial, industrial, and high-performance buildings. “These quad-pane windows provided better thermal insulation and because they have the same weight and thickness as a double-pane window they were easy to install. By improving the building envelope, they can help contribute to our net-zero goals,” said Tyler Cooper, Supervisory Energy Project Manager at GSA Denver Federal Center.
“The conclusions didn’t surprise us as we’ve known for a long time that higher performance windows provide phenomenal value,” says Brad Begin, CEO of Alpen High Performance Products. “Both thin glass and suspended film technologies are readily available, and we are appreciative of the opportunity to partner with the U.S. General Services Administration and National Renewable Energy Laboratory through the Green Proving Ground program to be able to provide this field test and validated, third-party data.”
Begin adds, “With climate change advancing rapidly, we hope more designers, consumers, and decision makers use these test results to accelerate product choices to higher performance window options.”
Several other factors were tested and evaluated, such as thermal comfort, thermal performance and ease of installation. Click here to view the summary report.