Red Light, Green Light

I'm probably the only one that is confused as to the association of the red vs. Green light atop the elevator bank with down vs. up. I honestly don't know which is which (red up or red meaning down) and I thought it was only this screwy building, but no. I was in another buiding and there it was. Red light. Green Light. Well WTF? Did I miss something? How does a color make an association with going up or down in the elevator? Was there a sale on colored bulbs? What's wrong with the good old fashioned arrow?

I must have been out that day in kindergarten because I just thought Red meant Stop and Green meant GO. I didn't realize it hailed vertical direction as well. I serious don't want to get IN the elevator when it's red (stop) and I sure as hell don't know which direction it's going. This must be some sort of old-age indicator.