Commercial Secondary Windows Field Test

The Northwest Energy Efficiency Alliance (NEEA) contracted with Energy 350 to lead a field study for commercial secondary windows (CSW), a product that NEEA identified as an envelope improvement technology with energy-saving potential.

From 2020 – 2022, Energy 350 assessed the energy savings potential, reliability, non-energy benefits, and simple paybacks of six commercial secondary window installations in the Northwest. This report summarizes product selection, installation, field-testing, and energy savings analyses of those projects, from project initiation to completion. It also highlights opportunities to overcome existing barriers to market adoption of CSWs, including high upfront cost and lack of familiarity of the product by installers.

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