Overseer Dilemma

The new house was almost complete. Just the finishing touches were being ironed out.
The site overseer was onsite with the new owner discussing finer details.
The colour scheme for the rooms was the current task. They walked from room to room.
For the kitchen she asked for a nice shade of blue. The contractor wrote this down and then quickly walked to the window, opened it, and yelled out "GREEN SIDE UP!"
In the master bedroom she told the painter she would like it painted in a soft yellow. He wrote this on his pad, walked quickly to the window, opened it, and yelled "GREEN SIDE UP!"
The lady was somewhat curious but she said nothing.
In the 2nd bedroom she said she would like it painted a warm rose color. The painter wrote this down, walked quickly to the window, opened it and yelled "GREEN SIDE UP!"
She couldn't control her curiosity.. She had to ask.. "Why do you keep yelling 'green side up'?"
"I'm sorry," came the reply. "But I have a crew of blondes laying turf at the house across the street.