Matthew Chalifoux, principal with EYP Architecture & Engineering, based in Albany, N.Y., is hopeful that when the ongoing “greening” and fire safety project at the Birch Bayh Federal Building and U.S. Courthouse in downtown Indianapolis is completed, “you won’t be able to tell what we’ve done.”

The $69.3-million Birch Bayh Federal Building project, funded by the American Recovery and Reinvestment Act, is providing work for nearly two dozen companies. Much of the work is being performed behind the scenes.

It’s a primarily behind-the-scenes project, which is why Chalifoux won’t mind if the general public doesn’t notice. The $69.3-million project, funded by the American Recovery and Reinvestment Act, is providing work for nearly two dozen companies, with a new fire protection system, high-tech HVAC controls and a “green” roof that will be covered with vegetation and also harvest rainwater to flush the building’s toilets.

The 105-year-old Beaux Arts landmark is in fine shape, and it’s the contractors’ goal to keep it that way. That poses a challenge for companies such as Ryan Fireprotection Inc. of Noblesville, Ind., which is installing more than 10 mi of sprinkler line and 3,725 sprinkler heads, protecting six times the area that was covered before.

The sprinkler heads are tucked unobtrusively so as not to disturb the architecture, including the main floor’s stone-covered walls and vast mosaic tile ceilings, which are decorated with an estimated 1.4 million hand-laid tiles.

“This building was not designed to have systems like this,” Chalifoux says. “This is about installing a modern, required system in a way that’s invisible.”

Perhaps the most unusual part of the project is the rainwater harvesting system. It will connect roof drains to five 2,000-gallon holding tanks that will collect rainwater to be filtered and fed into the building’s high-efficiency toilet fixtures. Doing so keeps rainwater out of the city’s combined sewage system and is expected to reduce the use of city water by up to 30%.

Creating this kind of system has benefits for the building owner and the city’s sometimes-overtaxed sewer system, but it also is a boost and a public proving ground for the green-construction industry, Chalifoux says. “This is the kind of industry being developed through LEED technology and conservation technology,” he adds.

About 30,000 sq ft of the new roof will be planted in drought-resistant vegetation that will soak up some of the rainwater not diverted to the toilets and pump about 18 trees worth of oxygen into the air. The roofing system doubles the roof life, provides better insulation and can be installed without any need to upgrade the structural system, Chalifoux says.

Improving energy efficiency is the project’s other main goal. The building’s HVAC system dates back to the 1950s and features about 300 manually operated, pneumatic controls around the building, says Greg Bielefeld, general manager with E Solutions Inc. in Indianapolis.

When the work is complete, those manual controls will be replaced by a single computer keyboard interfacing with more than 30 different systems. The result will be greater comfort and about 10% energy savings.

Here’s the other part of not being noticed: All of the work is taking place at night because the building is fully open and functioning during the day. Construction workers arrive about 7 p.m. and work until about 4:30 a.m. By the time the building’s occupants and visitors return in the morning, all traces of construction are gone.

“During the day it’s as if nothing is going on,” Chalifoux says.

It’s the largest Indiana project funded through stimulus funds, and it will continue through August 2012, Chalifoux says. “This building has had 100 years of life already, and if we do our job properly, we’ll be able to extend it for another 100 years,” he adds.