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Family room with built-in shelving and seating.
The keys to the Passive House system are
airtightness and moisture control. Success in these
areas requires not just careful design, but precise
construction. McGrew found an eager partner in
contractor John Allen of AllenBuilt Inc., who became a
certified Passive House builder himself.
“Once you change your approach to putting the
building together,” said McGrew, “it’s not difficult. The
mentality in the U.S. has traditionally been to slap it up
quickly. Passive House requires that you take a little
more time and have more supervision. I put together a
very clear set of drawings, and I drew a detail for every
kind of penetration [where any element intersects with
the building envelope].”
The house is built primarily of wood, a renewable
material that naturally sequesters carbon. Outside
walls consist of 2x6 studs with high-grade cavity
insulation plus continuous expanded polystyrene
(EPS) insulation on the exterior. Windows and glazed
exterior doors are triple-pane. The roof is framed with
2x12’s with cavity insulation plus a continuous layer
of 3.5” insulation on the outside. All penetrations
for plumbing and other necessary components are
thoroughly sealed. With modest supplementation from
photovoltaic panels on the roof, the house is effectively
Living room. Project: McGrew House net-zero-energy.
Washington, DC Meanwhile, McGrew also worked to ensure that
the project was responsible in terms of storm water
Architect/Certified Passive House Consultant: Robin McGrew, management. She took advantage of DC’s River Smart
AIA, LEED AP, PHIUS CPHC Homes program, which offers incentives for installing
Structural Engineers: Linton Engineering, LLC rain barrels, a rain garden, a water infiltration garden,
Mechanical Engineers: Think Little
Civil Engineers/Permit Services: CAS Engineering-DC, LLC and shade trees. These measures reduce the strain on
Energy Modelling/Passive House Consulting: Peabody Architects the city’s sewer system.
Third-Party Verification/PHIUS Rater: Conway Energy Perhaps not surprisingly, the spartan white
General Contractor: AllenBuilt, Inc. exterior of the house evokes contemporary residential
architecture in northern Europe. The simple form
All photos © Allen Russ/Hoachlander Davis Photography
PASSIVE-HOUSE AGGRESSIVE 69
