There are miniblinds that open vertically covering a window in a bedroom.

The window slides right to left to open and, on summer nights, whoever is sleeping in the room gets hot and decides to open the window while leaving the blinds closed for privacy and to block light from coming in . In the morning they get up and leave the house while forgetting that the window is still open behind the blinds. Besides this being a security issue to leave the window open when no one is home, hot air comes in during the summer afternoons wasting electricity.

I need some way to remind people to close the window before they leave in the morning. Maybe some kind of wireless, battery-operated window sensor and door sensor that set off a buzzer if both are open at the same time. This way if the person opens the exit door to leave the house and that bedroom window is still open, they will get a reminder to go back and close the window.

Does anyone have any suggestions to make it difficult to forget that the window is still open?