NEW YORK - Why does Target want the ceiling to feel high in some parts of the store and lower in others?

Why does it no longer paint all the walls red?

And why did it leave a large metal vault door intact against a wall of exposed concrete and brick in its soon-to-open store on the Upper East Side in Manhattan?

Joe Perdew knows the answers. Walking through stores with the affable leader of Target's store design is like taking a crash course in the principles of design and consumer psychology.

Perdew has been very busy the last few years as the cheap-chic retailer has been remodeling hundreds of stores and opening dozens of new ones every year in urban areas, repurposing spaces that might have previously been anything from a theater to a bowling alley. But he's not complaining.

"Literally, I've never had so much fun," he said on a recent walk around the 23,000-square-foot store at 70th Street and 3rd Avenue in New York.

In the past, Target tried to make its stores all look the same, he said. Not anymore.

"Just six or seven years ago, we wouldn't dream of doing a store like this," said Perdew. "It was a very different place. Now we're trying to make sure the stores are authentic and they're locally relevant...making sure you're letting the history of the building come through."

That's why Target decided to keep the giant vault door intact above escalators to the basement level – a remnant from when the hundred-year-old building was an FBI office back in the 50s and 60s. More recently, it had been a furniture store.

The store construction teams didn't know the vault was there until they began peeling back the walls. When they discovered it, they decided to keep it in homage to the previous uses of the building.

They also decided to leave a giant black "3" and a "5" on some of the columns on the lower level of the two-story store – the numbers marking what used to be parking spaces.

"Isn't that a riot?" said Perdew, laughing. "It literally was a parking garage!"

That's also why, for example, Target kept intact a retro sign outside a new store in Portland, Ore.. that went into an old bowling alley. And put "Target" on it to replace "Bowl".

But as for the exposed ductwork, piping, and fireproofing in the parking lot-turned-basement level of the Upper East Side store, Target's teams left those things visible for another reason. If they had dropped a ceiling over it to cover it up, the ceiling would have come down too low, said Perdew.

"We don't want it to become that low," he said. "There's a universal design principle that you want to expand ceiling heights when you want people to make holistic decisions and you actually contract them a bit, or shrink them, when you want people to make detailed decisions. So that's why it's OK to drop beams and stuff over produce because you're picking out that specific orange you want."

That's also why Target knocked out the mezzanine level of this building so it could have higher ceilings. It also replaced a bunch of vents with windows that wrap around the store to bring in more natural light. The pops of green that shoppers will be able to see of trees outside also makes for a more pleasant shopping experience inside, he said, referencing the "biophilia effect."

"It's bringing the outside in," he said.

Target is also being more judicious with its use of red in stores, relying more on neutral colors as a more modern backdrop against which splashes of red are used to have things pop out.

"The days of painting everything red are totally gone," said Perdew. "At the end of the day, it's got to be warm and inviting, easy and inspirational. Which means that juxtaposition between the warm and cool.

"You think about warm being welcoming and inviting and cool is about hip and aspirational. So it's that cross-section between the two."