In 2009, I had the privilege of welcoming an international delegation to a tour of my favorite building, the John Hancock Center in Chicago, on behalf of the Council on Tall Buildings and Urban Habitat -- read the TECHNICAL TOUR article. Before that day, the highest I had ever been in the building was "The Signature Room", a restaurant that occupies floors 95 and 96. I have not yet made it to the roof and the 100th floor "garage" between the two antennas, but I did have an even greater wish fulfilled, a chance to get behind the Hancock's signature "crown of lights" on floor 99.

The crown is perhaps the building's defining accent, a strip of white that runs the perimeter of the 99th floor. By day, it elegantly accents the mass of the black building. At night, it is lit with 552 95-watt, 8-foot "cool white" fluorescent tubes. At the time, we noticed the lamps being used were the Philips Econ-o-watt 96T12 CW/HO/EW/ALTO, about US$75 dollars for a box of 15 according to advertised prices on the Internet. This exact lamp is apparently no longer made and there are newer, more energy efficient versions.

For you tech-heads out there:

  • F96 = Fluorescent, 96-inch length
  • T12 = Tube, 1-1/2 inch diameter
  • CW = Cool White
  • HO = High Output, rapid start, t
  • EW = Econ-o-watt
  • ALTO = Philips' ALTO Lamp Technology, offers "increased energy savings and low toxicity in a slim profile"; they have since moved on to ALTO II
  • Color Temperature: 4100 K
  • Lumens: 8000
  • Average Lifetime: 12,000 hours
  • Power consumption: 95w * 552 = 52,400 = 52.4 kwh (more current models are 88w which would total 49.5 kwh).

For many years, I had tried to figure out how the crown was structured. Now that I've seen it, the closeup photos make sense: fluorescent tubes are mounted vertically in white metal fixtures set behind regular windows. This setup is actually indoors. The eight-foot tubes are contained within "lockers" that have white backgrounds to reflect and diffuse the light.

Some color correction in the photo brings out the details. 8-foot fluorescent light tubes are seen as dark vertical lines. They are mounted in 3's in white fixtures. Further back, the inner surface of the lockers provides a continuous white background.

The Hancock's topmost floor within the body of the building is a double floor, 98/99, for mechanical systems.  In the section we visited, 98 was the floor we were standing on and "99" was a catwalk against the windows. Since we were on a tour, I couldn't climb the ladder to the catwalk and see the lockers close up.  I gave my camera to the building's chief engineer and asked him to take some photos for me.  He snapped a few, but my wide-angle lens was not quite wide enough. There's a better look in a 2014 feature story done by Geoffrey Baer of WTTW-TV in Chicago.

I don't know what the total amount of light produced by all 552 of the 8000-lumen tubes would be, but if you've ever flown into Chicago at night, you know the crown can be seen from a long distance away. Not long after the Hancock opened, the crown had to be turned off to keep migrating birds from crashing into the building -- see Chicago Tribune articles from September 5, 1969 and September 9, 1970.

At some point over the years, the Hancock's crown was lit with different colors for various occasions. Today, this is an organized effort coordinated by the Chicago Building Owner's Management Association ( and their "Building Lighting Partner Program" where members light their buildings in similar colors for various causes. How do you get colored light from a cool white fluorescent tube? Put a colored sleeve over the tube. In October of 2o09, Chicago buildings were being lit in pink for Breast Cancer Awareness Month.  The building's chief engineer showed us a blue color sleeve. It takes two-man crew roughly 40 hours apiece to complete a changeover.

The crown of lights lit in pink for Breast Cancer Awareness Month.

In 2009, we were told the fluorescents would eventually be replaced by LEDs, where changing colors would be as easy as a mouse click on a computer. The 2014 WTTW story made mention of this same plan. LEDs are commonly used en masse on Asian skyscrapers with great effect, and we are all familiar with displays on those "ribbon" scoreboards in sports stadiums. In a 2010 visit to the Arrowvision / Crownvision control rooms at Arrowhead (Chiefs) and Kauffman (Royals) Stadiums in Kansas City, I discovered they were using Adobe AfterEffects to compose their scoreboard animations. Scoreboards in both stadiums were designed and installed by Daktronics, based in Brookings, South Dakota, which also designed the new left field scoreboard in Wrigley Field.

The Cool White crown is a bow tie on a tuxedo, an elegant accent for the most elegant and overpowering presence on North Michigan Avenue, Chicago's "Miracle Mile". For my part, plain, pure white alone is just fine. I would have to be convinced that ever-changing colors or maybe a coruscating ribbon would be suitable. As one piece in a coordinated skyline display? Then, absolutely. (Y'know, Chicago looks funereal at night compared to Hong Kong, Shanghai or Dubai. It is way past time to lose the PC poverty of energy attitude and start looking like a world class skyline.)

Details on our visit to other locations within the Hancock including mechanical floors and the 44th floor reception area (for apartments) and the grocery store are in the Technical Tour article.