You can spend all kinds of money in locks, access control systems and other high tech solutions to "guarentee" the perimeter of your building is secure and still find doors unsecured. In some facilities this is a constant cat and mouse game between administrators and employees. Here are few suggestions:
1. Change your lock core function. $$ For those with keyed locks consider having the cores of those locks converted to the "store room" function. This function only allows the key to be turned in one direction to open the door while the door remains in the locked mode. This prohibits employees from inadvertently turning their key in the wrong direction and leaving the door unlocked after they enter. For commercial building with panic hardware on the inside you would "dog down" the push bar when you want the entrance opened to the general admission. This is equally important if you have card access as you can override the card swipe by mechancially unlocking the door which would give access to anyone who simply pulls on the handle.
2. Sticks and stones. $ I look for these around loading docks and other doors that employees like to go in and out of without having to bother with their keys or card access. Remove these improvised door wedges and follow up with employees who frequently violate building security protocols to let them know that building security is a priority.
3. High tech. $$$$ If you want to be notified everytime a door is left open or adjar you can install a security system that will send you text or emails to notify you of when a door remains adjar or open for more than a few seconds. With these systems you can block out notifications during times of the day when you typically experience high volume at entrances such as the start of a school day or an evening concert.
Hope you find these three solutions helpful. This is John Baker for safetysolutions4schools.com