ned bonzi PhotograPhy, nedbonzi.com
ned bonzi PhotograPhy, nedbonzi.com
in addition to being a marvel of energy efficiency, the home makes use of sustainable options, with energy star appliances, fsc-certified lumber, salvaged
materials, drought-tolerant landscaping and a rainwater-catchment system for irrigation.
estration, due to its construction quality and high-performance glazing. Optiwin’s 3-wood, triple-pane windows with tilt and turn hardware have
thermally broken frames and multipoint locking
hardware that insure a nearly perfect seal.
Once the windows were installed, the first
blower door test was performed to determine
the building’s airtightness. On pins and needles,
the entire team waited to see if they had achieved
their goal. They weren’t disappointed and, in
fact, were stunned when the test results showed
0.4 air changes per hour at 50 Pascals, more than
30 percent better than the Passive House standard requires. Later they discovered they had
achieved these results with an unfoamed wiring
chase open to the outside!
of the home’s efficiency, only 30 percent of the
heat pump’s capacity is required for heating, and
next to nothing is needed for cooling. According
to Milburn, “It looks like this will operate maybe
a week and a half out of an entire year.”
Although the house originally had a chimney,
they are a dramatic source of air leakage and con-
ductive heat loss, so it was removed during the
renovation. To give the homeowner the option
of a cozy fire, the design includes an EcoSmart
ventless bioethanol fireplace. In the kitchen, the
gas cooktop is filtered by a recirculating vent
hood before an ERV duct in the kitchen exhausts
the pre-filtered air. The clothes dryer is a con-
densing dryer that needs no vent to the outside;
moisture removed from the clothes is captured
in a trap, which can then be emptied.
To provide the energy needed to operate the
mechanical systems and get to near-net zero, the
designers included a 2.15-kilowatt photovoltaic
(PV) system on the roof. The system comprises
10 SANYO HIT Power 215N PV modules and
an SMA Sunny Boy 5000-US inverter. This
small system covers 100 percent of the home’s
hvac Systems Slash energy demand
Ventilation in a Passive House is essential,
with its sealed envelope. Milburn chose the
UltimateAir RecoupAerator energy recovery
ventilator (ERV) with MERV 12 filtration as
the basis of the mechanical system. Ducts in the
bathrooms, laundry room and kitchen exhaust
moisture and odors before the ERV strips energy
from the outgoing air stream. The RecoupAerator has a 95 percent heat-recovery rating at full
flow and preheats (or cools) incoming fresh air
with the recovered energy.
Supplemental heat is supplied by a water-to-air heat exchanger coupled to a solar thermal
system, comprising three 4- by 6-foot Helio-dyne GOBI Blue Sputter panels on the roof and
a Heat Transfer Products SSU-80SB 80-gallon
solar storage tank. A Rinnai gas-fired on-demand
water heater provides backup heating for the
domestic hot water supply.
For backup space heating and cooling, Milburn selected a Mitsubishi Mr. Slim split-ductless
system, the smallest one on the market. Because
as u.S. vendors come on board,
Ph costs Will Fall
The project was completed in October 2010.
Since net metering began in March 2011, the
homeowner’s monthly combined electric and gas
bills have averaged less than $15. (The house was
unoccupied for years before the renovations, so
no historical data are available for comparison.)
The O’Neill retrofit was selected by the U.S.
Department of Energy’s Building America pro-
gram as a prototype home. To validate predicted
performance and track actual energy usage, the
DOE installed monitoring equipment during
construction, making all data available online for
immediate analysis. In addition, Lawrence Berke-
ley National Laboratory installed equipment to
monitor the electrical loads of the plugs.
beth Sereni, marketing and content manager for Pas-
sivWorks Inc., has worked with builder Rick Milburn
since early 2009. After working with Rick and seeing
the enormous potential for reducing energy demands
in the United States, she has become a Passive House
advocate and ad hoc writer.
graham irwin, principal of the Passive House consult-
ing and design firm Essential Habitat, has more than
20 years experience in the construction industry as a
builder, designer and consultant. A long-time environ-
mentalist, he recognized the value of Passive House
immediately and was one of the first Passive House
consultants trained in the United States.