Lightweight Quad-Pane Windows

Advances in film and thin-glass technology have made lightweight quad-pane windows a cost-effective alternative to typical double-pane windows.

Researchers from the National Renewable Energy Laboratory found 24% average HVAC savings compared to high-performing double-pane windows. View full-size infographic. [PDF - 296 KB]

GPG Findings 048, November 2021, Lightweight Quad-Pane Windows. Opportunity: Windows areresponsible for how muchenergy use? 34% OF COMMERCIAL BUILDING HVACENERGY IS LOST TO WINDOWS. An improved building envelope minimizes HVAC loads and contributes to Net-Zero goals Technology: How are Lightweight Quad- Pane Windows made? 4 PANES IN INSULATED FIBERGLASS FRAME WITH WARM-EDGE SPACERS & KRYPTON GAS. R-8 RATED FULL-FRAME INSULATING VALUE 2 configurations: 2 outer panes of low-e glass containing either 2 panes of thin glass or 2 layers of suspended film. Measurement and Verification. Where did M and V occur? NATIONAL RENEWABLE ENERGY LABORATORY (NREL) assessed quadpane windows provided by Alpen High Performance Products at the Denver Federal Center. One option used thin glass and one used suspended film. Results: How did Lightweight Quad- Pane Windows perform in M&V? 24% AVERAGE HVAC SAVINGS compared to high-performance double-pane window SUSPENDED-FILM CONFIGURATION SAVED 1% MORE ENERGY THAN THIN GLASS OPTION. HVAC CAPITAL SAVINGS REDUCES REQUIRED SIZE OF HVAC EQUIPMENT; MODELING ESTIMATES $120K IN EQUIPMENT SAVINGS FOR A 498K SF BUILDING. SAME INSTALLATION IDENTICAL THICKNESS, COMPARABLE WEIGHT, ~10% MORE EXPENSIVE THAN HIGH-PERFORMING DOUBLE-PANE. Positive Return on Investment Across Climate Zones Payback < 3 years at average GSA utility rates, $0.11/kWh and $7.43/MMBtu. Higher-efficiency windows can reduce HVAC capacity requirements and should be factored into the economics of any new construction or major renovation project. Deployment: Where does M&V recommend deploying Lightweight Quad- Pane Windows? ALL NEW CONSTRUCTION END-OF-LIFE WINDOW REPLACEMENT Thin-glass configuration is more cost-effective. Suspended-film version offers versatility in low-e coatings, meets tempered glass requirements, and is about 1 lb lighter per square foot than the thin-glass configuration. [PDF - 296 KB]


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Last Reviewed: 2022-05-06