The objective this project is to substantially increase thermal insulation of existing windows and transparent façade elements to reduce energy loss and to increase thermal comfort while causing minimal disruption and at reasonable cost. This will be accomplished by utilizing vacuum insulating glazing (VIG), installed in a frame and applied over an existing window on the interior side of a building, in a solution known as a secondary window system (SWS). Vacuum insulated glazing technology has been under development for the past 30 years.

Based on thermal modeling using Lawrence Berkeley National Laboratory’s WINDOW and THERM software tools, the project team will determine expected thermal and solar-optical performance and fine-tune design and placement of the SWS to maximize performance. Baseline thermal performance of the existing windows will be first measured in situ prior to the installation of SWS. The measured period of performance will be 3-6 months in the winter period allowing for full characterization and any thermal model calibration, as appropriate. During this period laboratory measurements of the thermal performance of SWS components and same or equivalent window system setup (depending on the availability of the baseline window) will be measured in a thermal chamber to validate thermal modeling results of the baseline window plus SWS. After the installation of SWS, in situ measurements will be performed on the site resulting in measured savings and documented in the final report. Based on the calibrated model, annual energy simulation will be performed for different weather locations and using EnergyPlus software tool (National Laboratory of the Rockies 2025) to extend results to other locations.

Vitro Architectural Glass, North America’s largest glass manufacturer with over 250 years of combined glass manufacturing experience, is providing VIG solution VacuMax™ with R-values of up to R20. A VacuMax™ VIG unit is an engineered solution comprising two lites of fully tempered safety glass, separated by a non-leaded proprietary metal edge seal and a vacuum space and held apart by an array of small metal pillars. Advanced Impact Technologies (AIT) Thermolite division is a technology provider for the framing and integrating VIG into the SWS. AIT possesses expertise in surveying existing windows, fabricating framing that fits precisely into the existing opening and installation.

Successful demonstration of SWS windows will yield significant annual energy savings due to increased insulation of the building envelope. Reduced heating, ventilation, and air conditioning system size in deep retrofits will also offset the increased cost of premium VIG glazing. Increased resilience to the extreme weather conditions will positively contribute to the readiness of the military site. The installation of the SWS is projected to take less than one day, so it can be done overnight or on weekends, eliminating any downtime. By extending the results to other locations using calibrated energy simulation will provide guidance to other facilities and bases when it is appropriate to apply SWS VIG solution. (Anticipated Project Completion - 2028)