Twenty-Year Payback for Embodied Carbon of Triple-Glazed Windows
Triple-glazed windows may save more energy than double-paned windows, but a recent study conducted by U.K.-based consulting firm Inspired Efficiency and footprinting expert Circular Ecology finds that in terms of their life-cycle carbon footprint, they don’t necessarily come out ahead.
Researchers determined that the embodied carbon of an average triple-glazed window is 51 kgCO2e greater than a double-glazed window with the same frame type because of the carbon dioxide emissions that are released from extraction, refinement, transport, and processing of the additional layer of glass and pocket of gas between the panes. It would take almost 20 years for a triple-glazed window to pay back this additional embodied carbon—longer than the lifetime of many windows.
That doesn’t mean you shouldn’t specify triple-pane glazings; there are other benefits, including operational cost savings, construction cost savings from smaller mechanical systems, improved thermal comfort, and acoustics to name a few. Furthermore, if customers are seeking to reduce their carbon footprint, frame choice has a far larger impact, according to the researchers. Choosing wood over PVC saves 25kgCO2e—10 years’ worth of operational savings—so over 20 years, a triple-pane, wood-framed window will have a lower carbon footprint than a double-pane window with either a PVC or aluminum frame.
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Published August 3, 2014