Replacement Windows is a written note in Dishonored 2.
To the house staff,
Well them workers are comin tonight to fix up that window. It's the only time I could gettem to come, and they made a big stink about how busy they was for months now, and tonight's the only time they got fer us.
The note can be found during the mission A Crack in the Slab. It is by a window in the Great Hall of Stilton Manor in the past, and on the window in the ruined present. If the workers never installed the window, it is not available in the present.