Here's a thought. From what little I know about how deep bass sound waves propogate I think if you are going to damage your windows (and that is certainly possible) you are as likely to do it regardless of where you place the subs. Also, consider whether or not there is a bass node where you are placing the sub.
To prevent damage caused by 'window' rattling sound (which is not necessarily the province of deep bass alone) damp the window panes or just turn down the volume a bit.
FWIW I recently traced a 'buzz' like vibration in my room to a framed picture on the wall. This was not caused by excessive bass. Just placed a little damping materiel between the bottom of the frame and the wall and it went away.
To prevent damage caused by 'window' rattling sound (which is not necessarily the province of deep bass alone) damp the window panes or just turn down the volume a bit.
FWIW I recently traced a 'buzz' like vibration in my room to a framed picture on the wall. This was not caused by excessive bass. Just placed a little damping materiel between the bottom of the frame and the wall and it went away.