In living color

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November 26, 2002 // UPDATED 1:33 pm - April 30, 2007
By: Tim Neuenschwander
Tim Neuenschwander

The Target tower's vivid rooftop has become an instant landmark. Here's how they make it glow.

On a clear night in the dead of winter, lucky Minnesotans can catch a rare glimpse of the Northern Lights. Now, thanks to the combined ingenuity of two Minnesota companies, Downtown-goers can see a lofty display of the same name every night.

For a little more than a year, the shifting, multi-colored panels atop Target Corp.'s 34-story headquarters have grabbed attention in a style like the discount giant's advertising: vivid, hip and full of life.

According to Target spokesperson Douglas Kline, the company turned to fellow Minnesota corporation 3M to set the 1000 Nicollet Mall rooftop apart from neighboring Downtown skyscrapers.

"It was developed in partnership with 3M at our request," Kline said of the design. "It is currently the only building of its kind in the world with this lighting structure."

The innovative lighting display consists of 130 glass pipes, each 30 feet long and weighing about 320 pounds, said 3M technical specialist Stephen Pojar.

Spaced five feet apart, each pipe contains a micro-structured film that allows colors to be mixed and rotated.

A 575-watt white lamp sits at the base of each pipe, shooting light through a series of three wheels representing the primary colors. "The color wheels are on a motor, and as they rotate, the color of the light varies," Pojar explained. "It's adding more of one of the primary colors so it can keep on mixing. The film lining in the pipe then carries the light up through the pipe and distributes it evenly throughout the penthouse area."

According to Pojar, a computer program integrates the lamps, allowing an infinite number of colors, patterns and sequences. The software also allows for various lighting effects, including fade out, shimmer and strobe.

"Each [lamp] fixture is capable of over one million different colors by varying the intensity of the primary colors in it," Pojar said. "All these things are capable of happening very quickly, so you could roll colors through very quickly. You could have flashing colors. You could probably make them look like fireworks if you wanted to. It's just up to the creativity of the programmer."

A patriotic start Target threw the switch for the lighting project on Sept. 14, 2001. Even though the initial lighting was planned to coincide with the building's opening later that month, it was pushed up in response to the Sept. 11 terrorist attacks. In honor of the tragedies' victims, the building was aglow in red, white and blue.

More commonly, the rooftop is decorated in a collage known as "Fire and Ice," which Kline describes as "a glowing, modulating pallet of warm tones alternating with a glowing pattern of cool tones." There are no immediate plans for special color mixes, but Kline said that "Downtown denizens can keep their eyes skyward for seasonal colors as the holidays approach."

Don't poison the tenants 3M's Pojar said he made many adjustments to make the display safe and feasible.

The lighting structure was placed in the building's air-intake area, so designers had to work closely with Minneapolis building inspectors to ensure that the lighting used only non-combustible materials. Pojar said combustibles would raise the risk of noxious fumes seeping into the building if the lighting structure ever caught fire.

The 3M technicians also had to plan for Minnesota's harsh winters. Pojar said the lighting pipe supports had generally only been used inside facilities such as auto assembly plants, airplane hangars and swimming-pool complexes. To overcome the climate's obstacles, 3M turned to Denmark-based Martin Professional, which specializes in outdoor color-mixing light engines.

"I was looking at a couple of different companies, and Martin had over 100 light engines installed to light bridges in Chicago, an outdoor environment with a climate that was similar to ours," Pojar said. "We're going to be doing some more buildings the same way, and we're forming a good relationship out of all this."

Pojar said that louvers invisible from the ground are interspersed between the panels to allow fresh air into the building.

Just the beginning While Target required the lamps to be low-maintenance, Pojar said the lights will likely need to be changed annually, depending how often they're lit. Kline said that the lights are set on a timing mechanism and are first turned on at dusk. They then shut off at approximately 1 a.m., and are re-illuminated for the start of the morning commute if the season allows it.

Though the design was done specifically for the Target headquarters and conceived as a one-time project, Pojar said that 3M has plans to sell the technology more widely. He said that the company is currently working on a design for the Newport Office Center in New Jersey, whose lighting fixtures should be up and running by early next year.

The technical specialist added that 3M and Martin Professional are also collaborating on improvements for the current system, including a light pipe that could be mounted on the exterior of a building and not require a glass shield around it. The effect would create a strip of color around the building, which Pojar said would appear to be "a giant neon tube." He said the companies are hoping to introduce the improvements some time next year.

While the display makes the Target complex stand out in the Minneapolis skyline, Kline said that the true purpose of the project was to present citizens with a unique gift that would set the Minneapolis Downtown apart from other urban centers across the country.

"The Northern Lights just help provide another attractive beacon for Downtown Minneapolis," Kline said. "It helps provide interest and differentiation in Downtown Minneapolis. It adds to the cultural and attractive fabric of the Downtown. It seems to be becoming appreciated as a new local landmark."