I recently gutted my basement in an early 1900s home that was finished in the mid-80s, and discovered a window! This window is directly under my front door, hidden by a deck that I've never really looked under in detail, so I've never noticed the window. The window is about a foot above grade, and again, covered by a deck, so it is not exposed to snow/rain.
I'm debating what to do with this, all my other windows are upgraded to newer windows about 4 years ago, but this is still a single-pane old-style window. I'm not sure if I should remove it and try and block it in with cinder blocks (Foundation is an old poured foundation), or is it acceptable to leave it as long as it's insulated and sealed? (I'd probably also cover the exterior of the Window with XPS and pressure treated plywood or something similar) The previous basement had fiberglass insulation, vapour barrier then drywall right over it, which I know won't cut it. My plan for finishing is hanging XPS boards directly against the concrete, sealing all the seams, spray-foaming any gaps around the boards, then 2x4 studs and Roxul batts as insulation. The R7.5 from XPS, plus R14 from Batts should give me approximately R22.5, which should be plenty.
Any advice? I know the "Best" thing would be to remove it, but is it acceptable to cover up a window should anyone ever find a need for it?
I've marked the "Answer" as to leave it. Excellent discussion for and against removing the window, but as mentioned, I think I'll leave it, insulate it and cover it from the outside. Who knows what other problems removing it could cause.