> I can't help thinking that it's an obvious energy waste. Probably depends on who pays the power bill. Maybe some commercial leases include power ? Also, in

> I can't help thinking that it's an obvious energy waste. Probably depends on who pays the power bill. Maybe some commercial leases include power ? Also, in NYC a lot of people work insane hours, so even one person staying till 9 or 10pm pretty much requires all the lights to be on. The housekeeping staff usually start about 7-8pm and assuming an 8 hour shift, thats 2-3am at least that they'll be there. Overall I bet lights are a very small fraction of a building's electrical bill. Think of an elevator and how many amps it requires to power a motor the size of small car lifting 900+lbs of people 30+ stories all day. One guy going to the top floor probably uses enough power to light the building for half a day.