Employees of the two agencies that govern Iowa’s utilities—the Iowa Utilities Board (IUB) and the Office of Consumer Advocate (OCA)—might be the ones who keep the power flowing, but are not the type to leave the lights on. On the rare occasion someone forgets to shut them off, sensors in the new office building will keep energy use in check.
The two-story, 44,640-square-foot IUB/OCA office building, designed by BNIM Architects, is located at the southeast corner of the Capitol Complex in downtown Des Moines. BNIM knows this context well, and has built its practice on sustainable design expertise. The recipient of the national 2011 AIA Architecture Firm Award, the Kansas City–based BNIM has a Des Moines office less than two miles away from IUB/OCA’s new building, which is a recipient of the AIA/COTE 2012 Top Ten Green Projects Award.
The LEED Platinum plaque is anticipated to arrive any day at IUB/OCA, but the architects are confident that the building exceeds certification targets: the building uses 67 percent less energy than similar structures that meet baselines established by code, according to initial data. The impressive statistics aside, what makes this sustainable building really stand out is its comfortable, light-filled interior environment.
A tale of two agencies and climates
Since the two agencies, which are required by state law to share space, represent different constituents—utility companies and consumers—some separation between the entities was necessary. BNIM created a V-shape layout with two wings adjoined by a common double-height lobby defined by walnut millwork walls and an intriguing cantilevered metal stair. The north wing houses the offices of the IUB, while the OCA occupies the second level of the south wing. Communal spaces, located on the first floor of the south wing, include a hearing room, a conference center, and a lounge. These spaces provide opportunities for informal interaction between the agencies and their visitors.
The building is designed to adjust to Iowa’s extreme seasonal swings. “Energy drove every decision, from the layout of the floor plan to the building orientation and placement of glazing,” explains Carey Nagle, project architect on the BNIM team. Highly insulated exterior cladding, comprising white Thermomass precast concrete panels, zinc panels, and high-performance glazing eliminate thermal bridging.
Seeing the light
Energy efficiency was a primary design goal, and adequate daylighting goes hand-in-hand with that to reduce the need for artificial light. The architects kept the floor plate narrow and oriented the building to gain east-west exposure. They designed parabolic louvered sunscreens that strategically line the facades, while horizontal aluminum blades and interior vertical fabric panels allow light to penetrate deeply, no matter the season. Solatube skylights deliver natural light to the few spaces not adjacent to windows, such as conference rooms located in the core.
The IUB and OCA had previously rented office space within a converted warehouse with few windows, so the abundance of natural light in the new building has been a welcome change, according to Judi K. Cooper, deputy executive secretary of the Iowa Utilities Board. An open-office layout and workstations with low, translucent panels are not only effective from a daylighting perspective, but they also encourage employees to talk to rather than email one another. However, employees can still expect some email traffic—a building automation system gauges weather conditions and sends helpful messages indicating optimal times to open or close the windows.
Elevate everyday materials
Much of the building’s budget was earmarked for systems that up its energy efficiency, including geothermal wells and photovoltaic panels, so the architects kept interior finishes simple and economical. Careful detailing allowed them to achieve a clean look, with the aim to “elevate the everyday materials through design rigor, and allow single material systems to serve multiple roles,” says Nagle. For example, the precast panels that clad the exterior serve double-duty as the interior wall finish, eliminating the need for additional drywall and the extra dust created from its installation. Structural members as well as acoustical composite and finished concrete decking were left exposed, and since the building is under three stories tall, no fireproofing was necessary.
The Iowa Utilities Board and Office of Consumer Advocate Building serves as a model for energy efficiency—perhaps the ultimate example of “practice what you preach.” But the project also proves that neither comfort nor aesthetics should be sacrificed, even on a limited budget. BNIM’s design just might establish a new paradigm for performance, both measured and perceived.
Key Design Highlights
- Using a V-shape plan allowed the architects to provide the two entities the separate interior offices they require, while still encouraging interaction in common spaces.
- Building orientation, placement of glazing, and insulated cladding material selection offsets solar heat loads.
- Louvered screens protect against harsh sunrays but allow daylight to penetrate the interiors.
- Solatubes bring daylight to the spaces of the windowless core.
- Sustainable energy efficient systems include photovoltaic panels and geothermal wells.
Iowa Utilities Board and Office of Consumer Advocate Building
Designer BNIM Architects
Client State of Iowa
Where Des Moines
What 44,640 square feet on two floors