Passive House design is the greenest of green architecture. Passive Houses—well insulated, virtually air-tight buildings that require little energy for heating or cooling—can decrease the overall energy consumption of buildings by an astounding 75 percent. The Greenest Home (Princeton Architectural Press, 2013), by Julie Torres Moskovitz, features homes that are not only remarkable for their high energy efficiency, but also for their elegant and forward-thinking designs. This excerpt discusses the Hudson Passive Project, and the economical benefits of these green home designs.
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Hudson Passive Project
Dennis Wedlick of Dennis Wedlick Architect (DWA), based in New York City and Hudson, New York, seized a moment late in 2008, after the real estate crash, to reflect on the mistakes of urban sprawl and the trend toward large homes. He decided to take the opportunity to design, with his staff and collaborators, an economically feasible and sustainable home that could serve as a prototype for home buyers. The model house born from this initial idea is the 1,650-square-foot Hudson Passive Project located in Claverack, New York, and completed in September 2010.
The building is simple in its design, with a cathedral form and south-facing glazing to optimize solar gains. Its shape was inspired by the original Long Houses built in this region by the Iroquois that were open at the southern end to receive the sun’s warmth and light. The building’s form and the use of large Structural Insulated Panels (SIPs) help minimize seams and joints where air leaking typically occurs. The east and west elevations of the house recall the basic, pure form of the Dutch barn, a shape native to the Hudson Valley, which was part of the early New Netherland settlements. The sides are clad in local granite rock, adding elegance but only negligible thermal value.
The structure is composed of custom-designed beams that hold the SIPs in place. Made from southern yellow pine, the beams are glue-laminated to form elegant arch-bow curves that allowed the architects to maximize the building’s span and minimize joints. Built off-site and set into place, the SIPs, which meet the airtight-layer and thermal-insulation requirements necessary for Passive House certification, are eight by twenty-four feet and faced with oriented strand board (OSB). Under the foundation slab are twelve inches of rigid extruded polystyrene (EPS) insulation.
From his many years of building single-family residential homes and realizing several client-driven sustainable projects, Wedlick knew that green architecture is not about using a high number of sustainable-energy technologies in a project but about reducing the home owner’s energy demand for running a residence. Once the architect had decided to create a Passive House prototype, he was not only able to convince his contractor and a team of talented consultants and manufacturers to collaborate on the project but also to persuade the New York State Energy Research and Development Authority to support the endeavor with a grant. As a result of the collaborative effort, DWA’s Hudson Passive Project was the first Passive House certified in New York State.
Paul Reidt, of Kochman Reidt + Haigh cabinetmakers, based outside Boston, was one of the team members called in to bring the project to fruition. The building’s A-frame shape resulted in a lofted space that was kept open at the second floor to allow the airflow to easily reach all areas of the house. Reidt’s refined cabinetry insert divides the second floor intimately and creatively to define two separate spaces—a TV room and a guest bedroom. The loft’s angled entry space is defined by the massive exposed structural beams that can be touched as one passes by.
Southern yellow pine lines the walls of the double-height ground-floor living area, continuing into the master bedroom to create a warm and comfortable interior. Sponsors, such as Waterworks, which supplied bath and kitchen fixtures, added luxury to the simple yet high-performing design. The house’s Heat Recovery Ventilator system consists of a manifold of supply and extract ventilation ducts that are cleverly hidden from sight.
During the winter months, the house hardly requires heating, as the sun warms the interior through the south-facing facade. The two-foot roof overhang shields against the hottest summer sun, and the low solar heat gain coefficient (SHGC) specified for the glazing prevents excessive solar heat gain during the warmest months. Operable skylights capture summer breezes, and a wall-mount air-conditioning unit is also readily available (but hardly ever needed). An electric instant tankless water heater provides hot water, and the small amount of supplemental heating needed in the winter is provided through a heat-pump system. There is no gas service to the building. Instead, an induction range and condensing dryer replace typically gas-driven household appliances.
During construction, meticulous site supervision helped the team achieve an airtight building that received an astounding blower-door test result of .149 ACH. When the SIPs, for example, first arrived on-site, there was an eighth-inch gap between the panels of rigid insulation. To remedy this open seam, holes were drilled in the OSB so that the gaps could be filled with spray foam and resealed. Today DWA’s Hudson Passive Project is one of the most energy-efficient homes in the United States and may have broken all records for airtightness.
Excerpt from The Greenest Home: Superinsulated and Passive House Design by Julie Torres Moskovitz published by Princeton Architectural Press 2013. Buy this book from our store: The Greenest Home.