New office building has pipes in the floor, so to speak, creating flexible and energy-efficient offices.

By JENNIFER BJORHUS, Star Tribune

Last update: December 4, 2010 - 10:29 PM

Two MarketPointe is packed with green features, from the high-performance glass in the floor-to-ceiling windows, to the sensors that automatically activate and dim the lights, to the water-saving dual-flush toilets.

There's even blue crushed glass in the pond-like feature in front of the building instead of water.

But the most innovative feature of the eight-story office building is something you can't see. It's underfoot. The building's floors are raised about 18 inches, and beneath the 40-pound concrete floor tiles is a pressurized space with power, voice and data cables, as well as the heated and cooled air that run above the ceilings in most buildings.

That may seem like a technical footnote only an engineer could love. But raised floors with under-floor air delivery (UFAD) can have a big impact on buildings -- including energy efficiency and workspaces where workers control their own temperature.

Two MarketPointe is one of only a handful of buildings in Minnesota, such as the Minneapolis Public Library, built this way, and it's the only multitenant office building in the Twin Cities with UFAD, according to Minneapolis-based Ryan Cos., which finished the building in 2008 and has plans for No. 3 next door to it.

More common in Europe, South Africa and Japan, UFAD is slowly catching on in the United States. About 7 percent of the new office construction in the country is now built this way, according to the Center for the Built Environment at the University of California-Berkeley, which tracks it.

"We're trying to get caught up here," said Brent Karkula, first vice president of CB Richard Ellis, which has offices in Two MarketPointe and is leasing it.

Two MarketPointe's floor was made by Haworth Inc. in Holland, Mich. There are other components to the UFAD system, such as the vents, thermostat controls and rooftop unit. It takes close coordination among all parties -- architects, engineers, developers and contractors, particularly on sealing off the under-floor space -- as well as whoever operates the building to make it all work right, said Bauman.

"Projects that have had trouble have typically fallen down in one of these areas, often through an inexperienced designer, contractor, building operator, or some combination thereof," Bauman said.

Tom Palermo agreed that air leakage is one of the biggest potential problems with the system.

"Once you've sat everybody down and explain it to them and keep an eye on it, it goes pretty smoothly," said Palermo, a partner at Eagan-based Master Mechanical, the heating, ventilation and cooling contractor on the building.

  
Raised floor with UFAD

Happier workers
The payoffs are notable. The most obvious benefit is flexibility -- running everything under the floor makes it a lot easier to get at to fix or reconfigure a space for a new tenant. That made UFAD a big hit in Silicon Valley during the dot.com boom, said Fred Bauman, a research specialist at the Center for the Built Environment.

"Just before the bubble burst, you could hardly get your hands on any raised-flooring material," Bauman said.

The system also eliminates the need for so many interrupting columns and allows for taller 10-foot ceilings. Plus, it enables a builder to use floor-to-ceiling glass that lets in more natural light and, for Two MarketPointe, allows some sweeping views from its spot on Interstate 494 at France Avenue.

Instead of forcing warm and cold air down through ceiling vents, the ductless air below wafts at a lower pressure up through the floor. The process requires less energy and helps keep the air cleaner, with fewer particles blowing around in it. Employees can easily adjust the vents in the floor to make their area hotter or colder.

Air flowing through vents along the base of the floor-to-ceiling windows create an extra "curtain" to help insulate against cold or heat from the glass.

"The whole package is meant to drive happiness and productivity," Karkula said.