Nestled in seven pristine acres of Hudson Valley forest, this intimate little spec home is sustainable, but not in the way you might think. It has no solar panels, no geothermal system, and no wind turbines, yet it’s expected to consume only one-tenth of the heating and cooling energy used by the average three-bedroom home. How does it work?
Like a thermos.
Think of it as a 1,650-square-foot version of that super-insulated bottle that keeps your coffee hot or your iced tea cold, except in reverse. Its ultra-tight shell keeps extreme temperatures out, most of the time with little to no mechanical intervention. And its main power sources are things nature provides for free: sunlight, shade, earth, and breezes.
Created by architect Dennis Wedlick and custom builder Bill Stratton, the “Hudson Passive Project,” as it’s known, doesn’t follow the same certification playbooks most American green builders have come to rely on. Rather than adhering to LEED or similar blueprints for sustainability (“I equate LEED with the IRS,” Wedlick says. “It’s about as much paperwork and it’s easier to cheat ... .”) the house is built to stringent standards set by the Passive House Institute in Germany. Under this rubric, certification is an all-or-nothing deal that’s wholly contingent on hard metrics (BTUs and pascals), not a points-based system. And the emphasis is on passive engineering and resource conservation. The design relies on simple architecture—not technology—to capture or shield the sun, depending on the season. The construction then ensures that not a single unit of precious thermal energy escapes before it is fully maximized.
Just how tight is this home’s envelope? Very. It received a blower door test score of .149 (the average score for a conventional home of similar size is 5.0). Based on the meticulous energy modeling that drove its design, Stratton predicts that its utility bills will come in around $1,200 per year—a notable cut below the $5,000 most local residents pay for their heating bills alone.
“Photovoltaics, wind, and geothermal technologies are often touted as the answer, but green energy alone is not the solution,” Wedlick says, noting that even renewable energy becomes wasted energy if it is allowed to seep right back out of a leaky building.
“Imagine sleeping outdoors on a cold winter night with a sleeping bag that has holes in it every 16 inches,” he explains. “That’s what happens when the blankets of insulation keeping a house warm can only be fitted between wall studs that stand every 16 inches, instead of completely wrapping the exterior structure.”
How does this unconventional house do it better? With a carefully engineered combination of solar orientation, calculated thermal bridging, and an extremely thick skin.
Seems Right Simple massing reduces the number of cracks and crevices where temperate air could potentially escape. Thermal energy loss is also mitigated by stacking and concentrating the utility core (yellow highlighted areas in the floor plans) to allow shorter duct runs.
For starters, let’s talk anatomy. Inspired, in part, by the Iroquois “long houses” that peppered the Hudson Valley landscape for centuries before modern A/C, the building is essentially one big rectangle with a high ceiling, and that’s no accident. Simple and economical to build, this form works in tandem with a large, south-facing window wall to make the most of what nature provides. In winter, the cathedral ceiling affords extra volume space to retain the sun’s heat. In summer, those same tall ceilings—combined with strategically placed skylights and operable windows—allow warm air to vent up and out when the house is open to the breeze. The plain box has other advantages, too. Its simple shape minimizes the number of joints in the envelope, reducing the potential for air leakage. “Simpler building forms also allow more compact mechanical runs,” Stratton points out. When duct, plumbing, and electrical runs are shorter, less energy is lost during transmission.