Designed by BNIM Architects, the offices of the Iowa Utilities Board and the state’s Consumer Advocate are both housed within this new LEED Platinum facility in the Iowa Capitol Complex. The building has been organized into two wings, joined by a central lobby; the north wing comprises the State Utilities Board on two levels, while the south wing houses the Consumer Advocate Office on level two, with common spaces on level one.
Considering the fair share of challenges the design team was up against—from the fact that the project is built on a 6-acre former landfill (which posed its own set of foundational issues) to the existing coal mine found 80 feet beneath the site—BNIM created a powerful example of how outstanding performance and elegant design can come together successfully within a limited budget.
“From a site perspective, it was kind of an awkwardly proportioned site that’s kind of a left-over section of the southeastern section of the State Capitol Complex,” says Carey Nagle, lead designer on the project. “What made it a particular challenge was knowing the level of exemplary performance we were tasked with meeting. We were certainly going to have to take advantage of appropriate solar orientation, meaning elongated access in the east and west directions.”
The state wanted to achieve an energy use intensity of 28.0 kBTUs per square foot per year—the equivalent of a 60 percent energy savings beyond the energy code baseline (ASHRAE 90.1-2004). “It all started with the owner’s strong vision and goals,” explains Nagle. “Every decision had to be measured against that energy goal.”
In order to achieve it, a number of strategies were implemented, such as a roof-mounted 45kW photovoltaic array and the use of white Thermomass precast concrete for the envelope of the building. A geothermal field tied to dual stage heat pumps accounts for 39 percent of the total energy savings.
Inside, the design team relied on a very simple material palette, with more than 50 percent of the ceiling remaining exposed; this reduction freed up funding to achieve the project’s ambitious energy goals. Sixty-seven percent of the materials used were regionally extracted, harvested and fabricated, and 35 percent of total material content was recycled.
An overarching theme of interconnection between the interior and exterior was also employed. More than 95 percent of regularly occupied spaces have daylight and views. All employees have access to operable windows and a building automation system identifies favorable exterior conditions, actually sending an email to occupants when windows can be opened or should be shut.
BNIM’s design has set high standards that many others are hoping to achieve in the future. “The state had a goal of using this building as a demonstration and as a prototype of sorts to help others not only within local and regional government to achieve the same results, but also in the private sector,” Nagle says.