Comment on Businesses Wasting Energy by David.
Having owned businesses, I will say that many do it for safety reasons. Some businesses will turn off half the light banks, which uses less electricity. I think that is a better way to go in this situation than leaving them all on.
The idea of using motion sensors sounds good as well. Then lights could go off at night or just leave a few key ones on.
In the businesses that my family has owned and managed, we all have turned the lights out at night.