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Soft House

Kennedy & Violich Architecture

Project Name

Soft House

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Year Completed


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Project Description

By Katie Gerfen from ARCHITECT July 2014

It is rare that a theoretical research project gets a shot in the arm years later, but for Boston-based Kennedy & Violich Architecture (KVA), that is the story of the Soft House. The prototype—a single-family residence where hard surfaces were replaced with soft ones that not only harvested, but distributed solar energy and ambient light—won one of the first R+D Awards in 2007. Though that project never got built, the ideas remained. So when KVA was invited to take part in a competition for the Internationale Bauausstellung IBA Hamburg to design a multifamily residence that re­defines sustainable living, the Soft House was reborn.

KVA—working with Buro Happold Engineering, Knippers Helbig Advanced Engineering, and a local wood builder—designed a series of four attached row houses along a canal in the city’s Wilhelmsburg quarter. Each unit is 2,411 square feet on three stories and incorporates three separate entrances so the bottom floor can be used as a stand-alone workspace or rental property.

The team wanted to use a wood structure because of the material’s carbon-sequestering attributes, but instead of a conventional frame the team turned to brettstapel, a German technique. “It is a very smart way of joining wood,” says Sheila Kennedy, AIA, a principal at KVA. Stacks of fir planks were connected by hardwood dowels that expand with humidity, creating a solid frame. The building was then clad in layers of mineral wool insulation, a water barrier, and a larch wood rainscreen. Photovoltaic ribbons form a canopy on the south side of the structure, moving and flexing with the sun to capture the most energy possible. The brettstapel timber structure is exposed on the interior floors, walls, and ceilings. “People who visited the house during the exhibition period commented on the smell of the wood,” Kennedy says, calling the result “incredibly peaceful.”

The living areas can be subdivided with a translucent curtain that runs along a curving track installed in the ceiling. The track is electrified by DC power, which offered a 15 percent energy savings overall because the power from the photovoltaic cells didn’t have to be converted to AC. The curtain offers shade, but also ambient light, given off by LEDs sewn into the fabric. While the structure was designed to Passiv Haus standards as a part of the brief, it is also a very active house, Kennedy says, noting that the energy-harvesting systems integrated into the structure allow for large windows that are atypical in passive homes.

One unit is currently occupied, and two others are under contract. But Kennedy hopes that the complex will continue to push the envelope over time: “We realized that if we could use a simple architecture, then it would be the infrastructure that could be moveable, upgradable, and replaceable.” The IBA will monitor the structure’s performance and will share the data with the architects. And as for the ideas that spurred the project in the first place, the team is continuing their research, and is taking the lessons learned from the German model and applying them to a multifamily structure closer to home, in Boston.

Project Credits:
Project Soft House
Client Internationale Bauausstellung IBA Hamburg (City of Hamburg)
Design Firm Kennedy & Violich Architecture, Boston
Design Team Sheila Kennedy, AIA, and Frano Violich, FAIA (principals); Veit Kugel (senior associate); Kyle Altman, Jeremy Burke, Stephen Clipp, Iman Fayyad, Patricia Gruits, Katherine Heinrich, Heather Micka-Smith, Chris Popa, Shevy Rockcastle, Phillip Seaton, Alex Shelly, Nyima Smith, Sean Tang, Diana Tomova, Sasa Zivkovic
Project Developer IBA Hamburg (IBA); Patrizia Projektentwicklung (Soft House)
Site Supervision Architects 360grad+ architekten
Landscape Architects G2 Landschaft
Structural Engineer Knippers Helbig
Climate Planning Steinbeis Forschungsinstitut für Solare und Zukunftsfähige Thermische Energiesysteme
HVAC and Mechanical Engineer BuroHappold
Soft House Manufacturing Consortium Global Solar Energy; Svensson Global; Philips Color Kinetics headquarters; Philips Research Eindhoven; Automatic Devices Co.; L-Tronics; Holzbau Merkle; Textil Bau
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