SOLAR TODAY - January/February 2011

Louisiana’s extreme climate made the
home’s environmental strategy as impor-
tant as the formal and spatial strategies. the
home is super-insulated and extremely well-
sealed, preserving the conditioned air inside.

insulation. As a result, the wall is much thicker than is typical, comprising
parts that each play a role in reducing the energy bill.

The walls use a combination of 24-inch on-center wood studs, 2 by 6
and 2 by 8 studs (throughout the double-height space). Balloon-frame
construction reduces through-wall wood thermal breaks. Using uncut
16-inch studs for the low wall and uncut 20-inch studs for the high wall
also reduces material waste. Optimum value engineering advanced fram-
ing techniques lowered material and labor costs and improved energy
performance for the building by minimizing thermal breaks and maximiz-
ing opportunities for insulation.
The space in between the studs and ceiling joists is filled with 100
percent water-blown, castor oil-based open-cell spray-foam insulation
free of HFCs and PBDEs. Then the whole house is wrapped with foil-
faced polyisocyanurate insulation — 1 inch on the walls and 2 inches
on the roof to eliminate all thermal breaks throughout the house, act as
a radiant barrier and increase R-values. The exterior fiber-cement clad-
ding is structured as a back-ventilated rainscreen system. Though the
cladding was not required by Passive House guidelines, Saft added it to
better manage moisture and, with its three-quarter-inch interstitial space,
to create a whole-house shading device. The rainscreen system allows
built-up heat to be vented before it reaches the insulated wall assembly.
XPS insulation is underneath the slab and inside the block basement wall.
Inside the house, added thermal mass from concrete counters, tile floor-
ing and extra-thick type ‘X’ drywall help to store the cool in the summer
and heat in the winter.
Other details include locally made, handcrafted steel and aluminum
shading devices, a 24-foot reclaimed cypress beam at the entrance porch,
a vertical garden defining the entry and an ultra-efficient second-floor
bathroom. The bathroom has a dual-flush low-flow toilet from Caroma
with an integrated sink above the tank so that when the toilet is flushed,
water automatically flows for hand washing on its way to filling up the
toilet ( caromausa.com). The walls of the bathroom are finished in off-cuts
of the exterior cladding and the floor is tiled with an integrated drain, so
the entire 3- by 6-foot bathroom becomes a shower enclosure.

building Photovoltaics Right into the Roof

After designing the house to consume very little energy, Saft viewed
active solar as the natural next step. Louisiana’s excellent incentives were
another big motivator.
He chose a BIPV system from Whirlwind Solar. Photovoltaic laminate
panels (each 18 feet by 16 inches and a quarter-inch thick) were adhered
to the Whirlwind Weather Snap Roof System in Whirlwind’s manufac-

coRey SaFt
A simple shed roof allows northerly light to illuminate the space inside,
while accommodating thin-film solar PV laminates. The laminate system,
from Whirlwind Solar, produces almost as much energy as the house uses
through much of the year.

turing facility. Jerry Meche of A-Plus Services in Lafayette installed the
balance of systems in December 2009. Saft liked how the panels made a
sharp pinstriping with only the standing seams of the roof panels standing
between them. With this configuration, the standing seam offers a level
of protection to the BIPVs, as well.
The laminates also offered several advantages over traditional PV
modules, according to Saft. First, the solar laminate system is less than 1
lb per square foot, lighter than the 3 to 6 lb per square foot typically added
with more traditional systems. Therefore, there were no additional foun-
dation or framing costs. Second, United Solar’s laminate technology is
better at capturing off-angle light than traditional crystalline solar panels.
Therefore, the PV laminate array does not need to be at the perfect tilt or
azimuth angle. The solar laminate uses Uni-Solar triple-junction amor-
phous silicon solar cells, with blue, green and red wavelengths absorbed
in different layers of the cell. It demonstrates superior energy production
in high temperatures, low light levels, cloudy conditions and shading,
according to the manufacturer. One overriding benefit is that the system
is penetration-free, meaning that there were no concerns about water
leaks or air infiltration.

The project was completed last February. Problems with the ERV last
summer make it difficult to report meaningful performance data to date.
Outside of this time, however, monthly electric utility bills ranged from
slightly negative to the mid-$20s.

Saft’s goal was to design and develop a durable, experientially rich and
environmentally sustainable urban prototype that was affordable enough to
make a significant impact on everyday practice. At less than $120 per square
foot, the resulting near-net-zero-energy home handily achieves these goals.
Three of Saft’s architecture students who are renting the house are tracking
energy usage, temperature and overall performance. Their findings will help
advance Passive House design in Louisiana and beyond. ST
Lynne Clearfield is an educator with backgrounds in both architecture and mod-
ern dance. she has taught in both the architecture and dance departments at
the university of Louisiana at Lafayette and also in the Lafayette Parish public
schools as a teaching artist. Clearfield writes on several topics including art,
architecture and dance. she writes this article with special interest, as she is mar-
ried to architect Corey saft.