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GPG OUTBRIEF 32
Ultralight Insulating Panels for Operable Windows
If you missed the latest webinar on a Green Proving Ground (GPG) assessment of ultralight insulated panels for operable windows, a recording of the webinar and presentation slides are now available.
Many thanks to the presenters and to the participants for their thoughtful questions, some of which are answered below:
Q: Is the 52% increase in insulation performance for the whole window or just the glass?
A: The U-value change from 1.15 to 0.55 was based on center-of-glass measurements. Rated U-values were validated via Intertek testing based on National Fenestration Rating Council (NFRC) standards.
Q: Could you explain how the insulation panel seals around the perimeter of the device to maintain the 0.5” gap and creates a seal along that perimeter?
A: The insulation panel seals to the glass surface by a plastic gasket on the insulating panel that presses against the glass of the primary window creating a dead air space between the glass surface and the plastic panel that is resistant to being washed by convective currents. The size of the dead air space is also spaced optimally to minimize the internal conductive and convective heat losses for an air-filled cavity.
Q: Are the panel tolerances forgiving enough that most building owners and occupants could take field measurements? Or would you likely need a vendor to size them to ensure they are correct?
A: The field measurements are easy to take, and most building owners/occupants can do it. However, the report recommends that the vendor take field measurements of the windows to avoid financial liability for incorrectly sized panels.
Q: Would you recommend this technology for fixed windows?
A: The primary benefit is for operable windows. If operability isn’t important, GPG has evaluated fixed-frame secondary windows that have higher performance. If air infiltration or noise are issues with the existing windows, consider alternative retrofit technologies that are mounted in a frame.
Q: Is this product permitted for use in historic buildings?
A: Yes. The technology does not impact the building facade’s appearance. The technology received approval by the GSA Historic Preservation Officer.
Q: Will cleaning agents damage the surface and reduce visibility over time?
A: The manufacturer has tested standard window cleaners as well as ammonia, bleach, and vinegar and not found any degradation to the panels. Cleaning agents should be wiped off with a microfiber cloth or Bounty Paper Towel; other paper towel brands can scratch the surface.
Q: The report said that some of the units fell off and had to be re-installed. Can you speak to that?
A: 27 out of 1,148 corner attachments separated from the glass: 44% of the detachments were attributed to the factory-applied fastener, 56% were attributed to field installation. The vendor has since improved the process for the factory-applied fasteners, and the field installation procedure now includes applying silicone sealant to reinforce the connection between the insulating panel and the primary window.
Q: What is the end-of-life plan for the plastic, and how much do they weigh?
A: The panels are estimated to have a 15-year life span and weigh 0.17 lbs/ft2. At end-of-life, the manufacturer states that the panels can be recycled.
Q: Are the lightweight insulation panels available commercially?
A: Yes. The ultralight insulating panel technology GPG evaluated was provided by WexEnergy. For more information, contact the manufacturer directly: Rachel Rosen, rachelrosen@wexenergy.com.
Reference to any specific commercial product, process, or service does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
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