Stairwell and hallway lighting. Motion sensors or timers?

[Steve Paduchowski]

I am wondering how other landlords are handling stairwell and hallway lighting. The building I am working on is a three family with 2 stairwells. Each stairwell has three windows and the lights on each landing are connected to a timer. I am considering adding occupancy sensors with a photocell on each landing as leaving the lights on for 10 hours seems like a waste. Thoughts? Thanks in advance.