Project Type: Single Family Residence
Location: Danby, New York
Year: Fall 2010
Related Works: Mass Regimes, Green Building & Design, Inhabitat, The Architect’s Newspaper, DWELL, EnCoding Architecture, Eliciting Environments, PITA’15, Liceaga Award, NYSCA’13, Berkman Fund, ACADIA’14, IJAC’15, MRS’15
The Hsu House is a small home designed using passive solar principles to create an inexpensive, ecologically sensitive, energy efficient dwelling for a growing young family. Rising out of a hillside south of Ithaca in upstate New York, the bifurcating roof covers a house organized around a three story main living space which functions as both a spatial nexus and a natural ventilation stack. The volume is divided by an interior south facing cast-in-place concrete heat sink mass wall, which stores energy and animates light, creating an all season solarium that, in the summer, opens and unfolds into the natural landscape. From the outset, the intention was to minimize the cost of finishes and fixtures and spend the budget on structure and systems. Consequently, the material palette is simple: bamboo, drywall, cement board and concrete; while the forms and spaces are more complex. The Hsu House is Silver LEED certified, with all walls being super-insulated underneath the cement board cladding. It incorporates a rainwater collection system, a high efficiency forced air heating with HEPA filtered heat recovery ventilation, a TPO high albedo membrane roofing system, energy star lighting and appliances, and high efficiency plumbing fixtures. Designed to be naturally ventilated, the house has no cooling systems. The house was originally designed to incorporate a custom thermosyphonic solar thermal heating device on the south façade, which will be installed in the spring of 2012 and should further reduce energy use and carbon footprint.
Design Principals: Dana Cupkova + Kevin Pratt | Design Team: Man Kim, Jamie Pelletier, Monica Freundt, Kyriaki Kasabalis | General Contractor: Hansen Design & Construction | Mass Wall Formwork Fabrication: CCC&M, LLC; Frank Parish, Cornell
The HSU HOUSE was carefully designed in an iterative process using thermal and daylight simulation software to balance day lighting and thermal performance. The relatively harsh climate in upstate New York precludes large areas of fenestration, and yet, with less than 30 percent of the total envelope glazed, the house is well lit at all times when the sun is above the horizon.
The exterior surface of the house features solar-responsive cement board siding pattern that transitions from dark to light according to its orientation.
Natural Ventilation: The central space of the house is three stories high, and openings in the envelope were strategically placed in relationship to the prevailing winds, thus the main body of the space operates as a ventilation stack during the summer. The cooling effects of the air movement are supplemented by radiant cooling from the mass wall, which is ground coupled and does not receive direct radiation in the summer months. Consequently, the house was built without any air conditioning; the best way to conserve resources is to omit the systems that use them.
Mass Wall: Given that the house was designed to be built with lightweight materials, a mass wall dividing the solarium from the main space of the house was considered necessary to damp diurnal energy fluxes and store absorbed solar radiation. The mass wall is 23 feet long, 14 feet high; its width varies from 5.5 to 16 inches. It was designed with three primary criteria in mind. First, wall surface area was maximized to increase the rate of thermal transfer between the sun, the wall, and the interior environment. Second, the shape was designed to allow light from the solarium to pass through the structure, allowing illumination of the north side of the first floor of the house. Third, the mass wall was designed as the sculptural focus of the house, defining the entryway, the kitchen, the solarium, and the edge of the triple height main living space.
A large number of parametric iterations were tested in relation to performance, aesthetics and fabrication constraints of the MASS WALL The primary concern was maintaining a level of porosity that would create a sense of lightness, allowing for views through the wall and to counteract the tendency of the concrete to read as a massive and unwelcome subdividing element in what is, after all, a fairly compact and spatially diverse living space.
The MASS WALL was parametrically modeled, while constrained to its fabrication logic. A series of iterations were tested in numerical simulation. Once a final design was arrived at, more than 100 guides were cut using a CNC milling device, which were then used to hand cut a high density polystyrene form liner that allowed for the wall to be completed in a single three hour concrete pour.