With its turrets, archways, and other rich ornamental details, Turnblad Mansion, which was commissioned in 1093, is known throughout Minneapolis simply as “the Castle.” Since 1929, this historic landmark has housed what is today known as American Swedish Institute (ASI), an arts and cultural center, and been part of a well-known residential neighborhood that has nonetheless endured some ups and downs. But a new LEED Gold–certified expansion, known as the Nelson Cultural Center, has given new life to the old mansion, reinvigorated its connection to the community, and become a vibrant destination for Twin Cities residents.
This summer, Sweden was named the most sustainable country in the world in a report by RobecoSAM, a Swiss investment group, in August 2013. The country’s strongly held environmental beliefs encompass both public and private ventures and include commitments to renewable energy and lowering CO2 emissions. When it came to designing the ASI expansion, Minneapolis-based integrated architecture and engineering firm HGA knew it needed to illustrate a deep understanding of Sweden’s culture, architecture, and holistic approach to sustainability.
Working in consultation with the institute, as well as Swedish designers Åke Axelsson and Karin Ahlgren, HGA designed the cultural center as a contemporary structure on the site of a former parking lot, which had formerly created an uninviting and confusing approach to the mansion. Encompassing 34,000 square feet and two floors, the new building provides a strong new entry point for the whole facility and offers gallery, performance, and meeting spaces, as well as a café. (The mansion is still open and houses additional galleries, a library and archives, and a performance space.) Despite its modern aesthetic, the new building complements the historic mansion in unexpected ways, including an exterior wrapped in slate tiles—the same material as the mansion’s roof—and an asymmetrical roofline that mimics the proportions of the mansion.
“We designed the new building to be respectful and not overpowering,” says Tim Carl, AIA, HGA's design principal on the project. “The mansion is still the centerpiece.”
Connectivity and open space were extremely important, according to the design team. Over the past 10 years, the institute had purchased the entire city block on which the mansion sits and envisioned the new cultural center and mansion working together as a campus, complete with inviting spaces that would link back to the surrounding neighborhood. The plan is built around the concept of a Swedish gård, or courtyard, framed by the two buildings. A largely transparent corridor links the mansion and the addition.
“We wanted to improve access to the mansion itself, both for patrons and also for supporting the collections,” says HGA project architect Andy Weyenberg, AIA. “We made sure to place the new stair and elevator tower in between the carriage house and the mansion, so that it disturbs the existing building as little as possible.”
The new building’s sustainable design elements deal with energy efficiency, water management, waste reduction, and environmentally sound materials. A geothermal heating and cooling system comprising 92 wells, as well as a maximum amount of daylighting possible and a vegetated green roof (planted with sedum and native grasses), have combined to produce a highly efficient building whose Energy Use Intensity (EUI) is predicted to be less than 70 kBtu per square foot per year. The system also reduces greenhouse gas emissions by approximately 272 metric tons per year, according to HGA.
Now, the site can handle 100 percent of its runoff, through the green roof, pervious surfaces, and an infiltration system basin under the parking lot. Low-flow fixtures have helped to reduce the building’s potable water usage by more than 40 percent below baseline. Low-emitting materials were chosen throughout the building, and more than 95 percent of construction waste was diverted from the landfill. And users are encouraged to visit the site via public transit, on foot, or by bicycle. The site has trails that connect to the city bike route system, and the number of parking spots is limited to the minimum required by code.
Although the rest of the landscape includes extensive native plantings, the courtyard boasts just a single Vårdträd—this “Guardian Tree” is a traditional Swedish symbol for faith in the future. “It was a very important for us to showcase the mansion and create welcoming outdoor spaces for people to enjoy,” says Bruce Karstadt, ASI’s president and CEO. “The courtyard that was formed between the two buildings is such an important space, where you’re able to appreciate both contemporary and historic architecture. The new building expresses our values in a variety of ways.”
By the Numbers
Building area: 33,452 gross square feet
Number of permanent occupants and visitors: 10 FTEs, 456 visitors
Percent of the building that is daylit: 96.33% of occupied spaces
Percent of the building that can be ventilated or cooled with operable windows: Zero
Total water used (gallons per year): 104,865
Calculated annual potable water use (gallons per square foot per year): 3.57
Total energy used (kBtu per square foot): 68
Percent total energy savings: 33% energy cost reduction
LEED rating: Gold
Architect, engineer, landscape architect, lighting designer: HGA Architects and Engineers, hga.com—Gary Reetz, AIA, principal; Michael Bjornberg, AIA, project manager; Tim Carl, AIA, project lead designer; Nancy Blankfard, Andy Weyenberg, project architects; Rich Bonin, Laurie Rother, interior designers; Craig Lemma, Scott Lichty, mechanical engineers; Sarah Jorczk, Gina Boogren, structural engineers; Helen Peterson, electrical engineer; Erik Hansen, civil engineer; Ross Altheimer, Erica Christenson, landscape architects; Tao Ham, Chrsyathani Stockwell, lighting designers
Client, owner: American Swedish Institute, asimn.org
Construction manager, general contractor: Adolphson & Peterson, a-p.com
Photographer: Paul Crosby, pcrosby.com
Air, moisture, and vapor barriers: Carlisle, carlisleccw.com
Ceilings: USG, usg.com
Cladding: Vermont Slate, vermontslateco.com
Curtain walls, windows and doors: Empirehouse, empirehouse.com
Flooring: Forbo, forbo-flooring.com; Altro, altrofloors.com; Lea Ceramiche, ceramichelea.it; Mirage, miragefloors.com
Glass: Viracon, viracon.com; Architectural Glass Art
Lighting control systems: Wattstopper, wattstopper.com
Lighting (interior and exterior): Pulse, pulseproducts.com; Cooper Lighting, cooperindustries.com; Kurt Versen, kurtversen.com; Winona, winonalighting.com
Millwork: Heebink Millwork
Paints and finishes: PPG, ppg.com