Energy loss through building walls is estimated to cost the U.S. Department of Defense (DOD) about $200 million per year, accounting for 5 % of the total energy cost in DOD facilities. This article describes the demonstration of a high-performance insulation material, called modified atmosphere insulation (MAI), to reduce wall-related heat losses in a DOD building located in Ft. Drum, NY, in a cold climate. MAI has been demonstrated to achieve R32/in. (hr-ft²-°F/Btu-in) or greater and its use can significantly increase the thermal resistance of walls with a marginal increase in wall thickness, making it an ideal candidate for retrofit application. MAI is a variant of vacuum insulation panels produced at a substantially reduced cost resulting from a change in the evacuation process. By retrofitting walls and increasing thermal resistance, as measured by R-value, by R10-20 (h-ft²-°F/Btu), reductions of 30 % or more over baseline wall-generated space conditioning loads are possible. Further, with targeted applications for older or more poorly insulated facilities, greater energy savings can be achieved. In this article, the installation of MAI panels in an existing building at Ft. Drum and the resulting energy benefits will be described. Like vacuum insulation panels, MAI panels consist of an evacuated nanoporous core that is encapsulated within air- and vapor-impermeable barrier films. Addition of these impermeable barrier films can have implications on the moisture storage and movement within the wall systems. Therefore, in addition to the thermal performance evaluation, measurements and modeling will be used to determine the hygric behavior of the retrofitted walls.