Research has shown that windows are left unlocked and open at a much higher rate than doors. An open window that is visible from the street or alley may be the sole reason for your home to be selected by a burglar. So take a few precautions to help make your house less of a temptation to a would be burglar. 

• Use secondary blocking devices to prevent sliding windows from being opened from the outside. 
• At a minimum, use wooden dowels to block horizontal sliding windows (and through-the-frame pins work well for vertical sliding windows). 
• For ventilation, block the window open no more than six inches and make sure someone can't reach in from the outside and remove the blocking device or reach through and unlock the door. 
• Secure double-hung sash windows by drilling a hole that angles downward through a top corner of the bottom window into the bottom corner of the top window on both sides of the window. Place an eyebolt or nail in the hole to prevent the window from being opened. 
• Replace louver windows with solid glass or some other type of ventilating window. If this cannot be done, glue the panes together with a two-part epoxy resin. 
• Secure casement windows with key-locking latches. Make sure that the protrusion on the window that the lock is attached to is made of steel and not worn, and that the window closes properly and is not bowed or warped. 
• Secure sliding-glass windows as described above for sash windows or by the same types of locking devices used for sliding-glass doors. 
• Consider installing security bars on side, rear, or other windows that a burglar might break to enter your home. Make sure that retaining bolts cannot be removed from the outside. Check to make sure that bars comply with Fire Code requirements for inside release to permit an occupant to escape in the event of a fire. 
• Reinforce the glass in viewing windows on the lock sides of doors so a burglar cannot break them and reach in to open the door. 
• Check to see if there is a key lock available for the type of window that you have on your home. 
• As a deterrent, place highly visible decals on the glass door near the latch mechanism that indicates that an alarm system, a dog, or block watch/operation identification system is in place.