Influence of climate on the environmental and economic life cycle assessments of window options in the United States

•Life cycle impact assessment and costing were used to analyze windows.•Extreme climates saw significantly larger energy savings from retrofitting windows.•Low-solar gain windows were best environmentally due to electricity reductions.•Each climate had a window choice which had a payback period of 10 years or less.•Retrofitting Atlanta's windows would reduce CO2 emissions by 0.5 MMT a year.

Life cycle assessments (LCA) of building materials often exclude the use phase due to variability in buildings and difficulties in isolating energy use for specific components of a building. For this study, a basic single-pane window was selected as a baseline to compare to two basic double-pane windows and four energy-efficient windows in a single-family home. Seventeen United States cities were investigated to represent 17 climate regions. Using energy simulations, along with life cycle inventory and economic data for windows, a cradle-to-grave LCA and life cycle cost (LCC) analysis were conducted. Environmental and economic impacts are normalized and weighted to identify the best overall performing windows. Environmentally, the low-solar gain windows always performed best due to the reduction in electricity needs, whereas economically they performed best in warmer climates but high-solar gain windows performed best in cooler climates. Thirteen of the seventeen cities had window options with a payback period less than five years when all retrofitting option were compared. When projecting the impacts of retrofitting a large number of homes, it was found that metro Atlanta could reduce CO2 emissions by about a half a million metric tons of CO2 annually with any of the energy efficient window choices.

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