The Carrick neighborhood in south Pittsburgh had been making the most of its branch library for decades. Granted, the small one-story building carved into a slope was cramped and cavelike, with the only natural light filtered through the glass block of the library’s front façade. But that didn’t stop library staff from developing innovative programming for local youth and adults and establishing the library as a hub of the community.
When it came time for the Carnegie Library of Pittsburgh to invest in a new Carrick branch, the Carrick staff and community knew exactly what they needed from the new building: light, space, and views to the outside. The tight site made this tricky, though.
“We found a way to create a two-story scheme on the existing site,” says Laura Nettleton, owner of Thoughtful Balance and the design partner on the project with NK Architects. “But the community felt they were being shortchanged. It still felt too small, and it didn’t really flow. They weren’t happy.”
In response, the library purchased the adjacent corner lot and tore down the building on it. That allowed for more space for the new library, although the site’s slope still put the ground floor several feet underground at the building’s back edge.
“We saw this rebirth of the Carrick branch as a chance to offer library users and staff a transformation in indoor air quality, comfort, and energy use,” Nettleton says. The concept of Passive House was not new to the Carnegie Library of Pittsburgh. Nettleton had worked with its Director of Facilities Development Ron Graziano, to apply Passive House design principles to the recent renovation of the nearby Hazelwood branch. Though Hazelwood did not quite make certification, Graziano liked the outcome: 16% less energy use despite a doubling of space, lots more light, and peace and quiet. Despite a tight budget for the Carrick project, Passive House design got baked in early.
Value engineering discussions later in the process did reexamine this commitment to Passive House, but it was discovered that it would be more expensive to excise Passive House from the project than to keep it, because all systems would need to be reengineered. That was a useful lesson learned: There is a point of no return once you have committed to high performance for your project.
“So we knew we had a bigger site to work with. We knew the building would be Passive House. We knew the library wanted lots of light, space, and views to the outside. But we also knew that budget constraints meant an elevator was off the table. Given the slope of the site, a single-story building would have been like a pancake dug into a hillside,” according to Nettleton.
A second story was needed, and so was accessibility. Enter NK Architects principal Steve Fischer.
“Steve came up with the brilliant idea of tying it all together with an interior ramp,” says Nettleton. “We had enough space inside to wrap a ramp with sufficient length to negotiate two stories. It meant we could build the library on different levels.”
The bookshelf-lined ramp starts at grade just behind the circulation desk. It then takes patrons up to the periodicals room, perched several feet above the circulation desk. Winding further up the ramp, you arrive at the adult stacks, which overlook the main reading room and are naturally lit by a clerestory overhead, fitted with sunshades to protect from western and southern light. As you take the ramp further, you arrive at the main meeting room, which overlooks the street.
Thanks to the staggered heights of these rooms, each has its own direct access to natural light and views outside. This design also allowed the team to really set the youth gathering space apart, sited in the southern corner of the first floor. The library’s teen programs have become a treasured community resource, with a popular videography program and creative community-building activities, and the library wanted to give them their own dedicated space. Nettleton’s interior design helps make the space work for both teens and younger kids. The Sett In Stone carpet introduces a biophilic theme to the space. Larger, adult furniture occupies the teen section of the youth area, while smaller, kids’ furniture inhabits the younger area. A story corner will feature a graphic describing the water cycle and the process of photosynthesis. Larger windows look out onto the entry plaza, with its rain sculpture cascading off the front of the building. Swales capture storm water on-site, a critical feature of the site design, given that the closest storm water outlet is 250 feet down the street.
Despite the design breakthrough of the interior ramp and its success at solving the aesthetic and daylighting challenges posed by the site’s slope, the design team still had to address the thermal and structural challenges of retaining all the dirt against the building. The team was not confident that the existing retaining walls were up to the task, so before the old library was demolished, new retaining walls had to be built inside the old building. NK’s Todd Demangone worked with Skylar Swinford of ESCO to build the PHPP model for the project, assessing the thermal implications of the retaining walls and determining the best way to offset them. The building’s windows turned out to be the most powerful lever for the Passive House design team, which selected a package that met the library’s desire to use U.S.-made components for the building.
During Carrick’s design, the team discovered a thermal isolation pad that worked very well for its needs: a compressed foam sheet that thermally isolates structural elements cost-effectively. The sunshades for the clerestory are being hung using this product to avoid thermal bridging there.
If all goes as planned, Carrick will be North America’s first Passive House-certified library. But more importantly, this centerpiece of Carrick community life will be a light-filled, healthy, and cozy space to read, learn, and connect.
|Heat Energy||Cooling Energy||Total Source||Air Tightness|
|4.2 kBtu/ft²/yr||4.9||36.3||0.6 ACH50 (design)|
Featured image courtesy of Thoughtful Balance and NK Architects