A display case door assembly for a temperature-controlled storage device includes an opening into the temperature-controlled storage device and a vacuum panel mounted within the opening. The vacuum panel includes a first vacuum pane of tempered glass, a second vacuum pane of tempered glass, and an evacuated gap between the first and second vacuum panes. The evacuated gap has a predetermined thickness within which a vacuum is drawn, thereby providing a thermal insulation effect for the vacuum panel. The vacuum panel further includes a plurality of spacers disposed within the evacuated gap and configured to maintain the predetermined thickness of the evacuated gap when the vacuum is drawn therein.