New traditions, new technologies
While the tradition of structural expression in Chicago's high-rise office towers may have been lost, the tradition of technological innovation has not. The latest advances, however, are literally invisible: from novel glazing materials and efficient mechanical systems to emergency power and robust telecommunications infrastructures, these buildings are lighter, thinner and wired to the gills.
"Tenants today demand technologically advanced space and risers with robust fiber and copper. In older buildings, riser closets are too small and not centrally located," says Daniel J. Slack, senior vice president with development firm The Alter Group, Skokie, Ill. "They demand flexible and ever-increasing power. The best new buildings have a 12-kVA riser, [which] is like having a substation in the building; tenants can tap into the riser with an additional transformer to go beyond 7 watts per square foot."
"Ten years ago, the Internet, multiple phone suppliers and satellite and microwave antennas weren't heard of, so the vertical path to accommodate those isn't there" in older buildings, says Lohan Associates' James Goettsch. "So they're moving into these new buildings to make their operations more efficient. It's a business-oriented thing."
Other advances include HVAC systems using low-temperature chilled water, which Slack and Goettsch say are very energy efficient and help offset the heat loads from computer-intensive offices-while using risers that are 10 percent smaller. Those systems would not be as economically favorable, however, if not for a utility-owned district-energy system that runs chilled water through the streets.
The building envelope is the beneficiary of accelerating advances in glazing technology. "There are entirely new technical possibilities, like low-e glass that has more than 50-percent light transmission, so it's not like a mirror," says Goettsch.
"That allows more light into the building, which makes people more productive," adds Slack.