Wear warm clothes. Sit under a blanket at home.

Another good one especially in larger houses is to make easily removable insulation blankets to put over windows in rooms you dont usually use or that dont need natural light or even over all of them after dark.

My simple tip. You A/C doesnt need to be set to 24 and everyone walking about in shorts. Set it to 18 to cut the cold and make everyone wear warm clothes with blankets.
What I cant tell you is how to convince the wife.

There’s two windows in my apartment that have a fly screen where the glass would be, so one idea would be to actually have glass in windows. If you have windows, double glazing is a thing that exists.