Smith notes that other glass products have since come on the market, such as Solarban, which is both energy-efficient and very clear.
On the building's other three elevations, the original steel windows were replaced with new aluminum-framed insulated-glass windows that mimic the profile of the originals — a modification allowed by the National Park Service because those facades are not considered "character-defining."
Just how did the project go from merely targeting LEED-CS 2.0 certification to achieving two Platinum ratings?
Gardi emphasizes that the team didn't "teach to the test" — that is, they didn't base the design on the LEED checklists, for the most part. Rather, the design evolved organically, informed by visioning exercises by Christman staff and SmithGroup.
As the architects developed the design, Gardi periodically reviewed it and estimated what level of LEED-CS certification it would likely achieve. It was only when the team realized the design was close to the Platinum level that they made an explicit effort to achieve the additional LEED credits. For example, they added a window to an interior office to ensure that 90 percent of spaces benefited from outside views.
At some point in the process, Gardi checked the LEED-CI 2.0 checklist and discovered that the office design had already reached a Gold level for that, too, putting the second Platinum rating within reach.
Christman took several steps to achieve LEED credits for innovation, contributing to both Platinum ratings. Those included planning a more environmentally sensitive housekeeping program, purchasing a high level of "green" power (100 percent of the Christman offices' needs for two years), and disseminating knowledge about the building's sustainable strategies through signage, a tour program, and a written case study on the project.
However modern its green insides may be, the building's exterior remains true to the original Elizabethan-revival style. Along with restoring the front windows, the project entailed analyzing and rebuilding the deteriorated facade.
Entering the building through its recessed bronze doors, visitors are welcomed by the showpiece of the interior restoration. In the main stairway, the Pewabic wall tiles, yellow sanded plaster, and verdigris bronze handrail finish were restored according to SmithGroup's research into the original colors and finishes. As the stairs climb, bluestone flooring gives way to a checkerboard of black and white linoleum tiles. The warm-colored historic finishes also continue into a first-floor corridor adjoining a row of restored walnut-paneled offices.
Before the renovation, this grand entrance had been choked by a lift system installed by the State of Michigan to provide wheelchair access from the front door to the first floor. The project team opted to remove the lifts and make the building's rear entrance accessible — a system that requires wheelchair users to be buzzed in before entering the building.
The first floor is occupied by the Michigan Municipal League and the third floor by lobbying firm Kelley Cawthorne. The Christman Company asked both tenants to sign ten-year leases to reduce the frequency with which the fit-outs would be altered, thus reducing construction waste.
Electrical submetering systems were installed in each tenant space to encourage lower energy use, and Christman provided sustainable design and construction guidelines for the fit-outs, which were designed by Mayotte Group Architects and built by Christman, with engineering by SmithGroup.
Smith recalls that when Christman purchased the vacant Mutual Building in 2006, "it was in pretty tough shape and deteriorating quickly."
While that presented some risk for Christman, the functionally obsolete building also offered a promising financial opportunity. The reuse project qualified for millions of dollars in economic incentives, including property tax reductions through the Federal Obsolete Property Rehabilitation Act, Federal New Market Tax Credits for developing a brownfield site in a low-to-medium income area, and state tax credits for redeveloping a brownfield site, as well as federal and state tax credits for rehabilitating a historic building.
Together, these incentives brought the project cost down from the actual total of $12 million to the effective total of $8.5 million, or about $132 per square foot ($1,420 per square meter) — a "remarkably reasonable price for corporate headquarters," says Gardi.
He estimates that it cost about $120,000 to get the project up to snuff for its two LEED Platinum ratings, relative to conventional construction. About 70 percent of that cost represents the time spent by Gardi and Smith to document sustainable features for the certification process. "It's remarkable how little LEED added to the bricks-and-mortar costs," says Smith.
The building's various efficiencies will mean lower energy use than in conventional offices, resulting in substantial cost savings over time.
The high-quality indoor environment at the new Chistman offices may also be saving labor costs. A recent study conducted by Amanjeet Singh, a masters student in construction management at Michigan State University, suggests that the new offices have reduced illness and absenteeism compared to the company's old offices. And, as Gardi is quick to point out, "Labor represents about 80 percent [of Christman's costs] versus 2 percent for energy."
Study results aside, he says the project is a clear hit with staff. "People love this building, love working in this building," he says.
Gardi adds that, having served as both general contractor and client, the company is pleased with how the project showcases its services, such as historic preservation, development of Class A offices, sustainable construction, self-perform capabilities, and integrated design. "It's worked out tremendously well," he reports.
Both Smith and Gardi emphasize the importance of integrated design. "Architects, engineers, and construction [folks] were working at the same table, and made a very concerted effort to understand each of the decisions they were making," says Smith.
Despite the challenges faced by the team on this complex project, Smith assures skeptics that "it's not that difficult" to do sustainable design.
Meanwhile, not satisfied with its two Platinum ratings under LEED-CS and LEED-CI, the Christman Company is applying for yet another certification: LEED-EB O&M, a measure of environmental friendliness in operations and maintenance of existing buildings. After a year of monitoring ends in summer 2010, the company expects certification at the Gold level.
The sixth-floor addition overlooks the Christman Building's atrium space.
A fifth-floor addition bridges the atrium, providing conference space above and below.
Extensive interior glazing in the Christman offices admits daylight to interior areas while providing a degree of separation.
The richly colored original materials in the main first-floor corridor were restored.
The "Mutual Cafe" is a common break room for all tenants of the Christman Building.
Christman Building ground-floor plan drawing.
Christman Building fifth-floor plan drawing.
Christman Building sixth-floor plan drawing.
A series of low segmental arches was preserved in the basement of the Christman Building.
From the main entry, a stairway with restored historic finishes winds toward the upper floors of the Christman Building.