Situated in the wine country town of Sono- ma, Calif., in a cul-de-sac of early-1960s ranch houses is one that is unique to this neighborhood, this state and, indeed, the
country. This little jewel of a modern farmhouse
is the nation’s first certified Passive House retrofit and California’s first certified Passive House.
Unlike many Passive Houses around the
world, this one looks more like a typical American house than an exercise in modern architecture. Homeo wner Cathy O’Neill wanted a retirement home that made a statement in energy
efficiency — one that set a benchmark — but
she also wanted it to be beautiful, warm and welcoming. In 2009 she purchased a rundown 1962
ranch based on its location and “good bones.”
To fulfill her wish of transforming this home,
she turned to Rick Milburn of PassivWorks,
with whom she had worked previously. Rick is a
staunch energy-efficiency advocate and a meticulous master builder.
Ph Standard Focuses on
efficiency, comfort
Rick and Cathy studied various eco-friendly building methodologies and decided on the
Passive House standard because
of its proven efficacy and simplicity. Three requirements are
needed to meet the standard,
which focuses on energy efficiency and the occupants’ health
and comfort:
1. Maximum heating or
cooling demand must not
by BETH SERENI
and GRAHAM IRWIN
exceed 1.4 kilowatt-hours (k Wh) per square
foot or 4. 8 kilo British thermal units (kBtu) per
square foot per year.
2. Total “primary,” or “source,” energy
demand must not exceed 11.1 k Wh per square
foot or 38 kBtu per square foot per year.
3. Air infiltration, or airtightness, must be less
than 0.6 air changes per hour at 50 Pascals.
Rick then completed the certified Passive
House consultant’s training at the Passive House
Institute US (PHIUS) in Urbana, Ill., and spent
three months studying before passing the rigorous exam. He enlisted Jarrod Denton, AIA,
of Signum Architecture to accompany him to
the birthplace of the standard, Germany, where
they attended the annual International Passive
Floor Plan
House Conference. They attended seminars on
design and building techniques and discovered
vendors of complementary materials.
O’Neill’s existing house in Sonoma presented some challenges. The 1,933-square-foot
(180-square-meter) eyesore had no street-front
entry. Its odd configuration consisted of two
structures connected by an outdoor breezeway.
Zoning rules and expansive soil on the site (soil
that expands and contracts due to moisture content) required that the footprint of the building
be unchanged and that the existing uninsulated
concrete slabs remain. Nonetheless, Rick and
Jarrod knew that they could remake it into something marvelous. Jarrod devised a way to connect the two existing structures with an angled
corridor that would comprise the new kitchen
and frame the courtyard. The result would be a
U-shaped house with an additional 400 square
feet ( 37 square meters) of space.
lail deSign grouP
extensive insulation,
airtightness are key
PaSSiv WorkS inc.
Because Passive House buildings have little
tolerance for air leakage, all electrical and plumbing pipes and cables in the interior walls were
run through holes bored through the framing
and all punctures to the exterior booted as on
the outside.
PaSSiv WorkS inc.
ned bonzi PhotograPhy, nedbonzi.com
Supplemental heat is supplied by a water-to-air heat exchanger coupled to a Helio-dyne solar thermal system.
To provide the energy needed to operate the mechanical
systems and get to near-net zero, the designers included
a 2.15-kilowatt photovoltaic system on the roof. This small
system covers 100 percent of the home’s electrical load.
ned bonzi PhotograPhy, nedbonzi.com
