Commercial Secondary Windows Field Observations and Decision-Maker Interviews Report

The Northwest Energy Efficiency Alliance (NEEA) contracted with Energy 350 to observe and document the installation of commercial secondary windows (CSWs) at several commercial sites across the Northwest states of Montana, Oregon and Washington. CSWs are a window attachment product with insulative and noise abatement benefits that are designed to address existing low-performing windows in commercial buildings. The objectives of this study were to identify the techniques, challenges, workaround solutions, and perceptions of the CSW product and the installation process and to identify influences on decision-makers’ choice to invest in CSWs for their window retrofit.

From 2021 to 2022 and in concert with a suite of NEEA-sponsored field tests, Energy 350 conducted onsite observations of the CSW installations and follow-up interviews with select market actors. Findings from the observations and interviews suggest that when viewed as an alternative to a traditional window replacement, CSWs provide a clear cost-advantage. Installation crews reported that CSWs are relatively easy to install. Although CSWs were universally viewed in a positive light by all market actors interviewed in this study, the pursuit of CSWs appears to be heavily influenced by non-energy impacts, such as improved thermal comfort or noise abatement. While decision-makers agreed energy savings was a consideration, the research did not find it to be a primary driver.

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