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Thermal mass, a well-insulated envelope, and a small grid-tied PV system come together to help this high-desert home generate more energy than it uses.
The adobe blocks were made on-site from the same clay, sand, and straw used to make the plaster finish for the walls. Nonstructural elements, such as the central bookcase, the dividing wall at the entry, and a bench in the great room, were constructed with the blocks, which provide additional thermal mass.
The adobe blocks were made on-site from the same clay, sand, and straw used to make the plaster finish for the walls. Nonstructural elements, such as the central bookcase, the dividing wall at the entry, and a bench in the great room, were constructed with the blocks, which provide additional thermal mass.
The adobe blocks were made on-site from the same clay, sand, and straw used to make the plaster finish for the walls. Nonstructural elements, such as the central bookcase, the dividing wall at the entry, and a bench in the great room, were constructed with the blocks, which provide additional thermal mass.
Nichos—shapes carved into the walls—are a tradition in both strawbale and adobe building, as pictured below in this historic rancho. Though they can serve specific functions, they often host objects of beauty.
Nichos—shapes carved into the walls—are a tradition in both strawbale and adobe building, as pictured below in this historic rancho. Though they can serve specific functions, they often host objects of beauty.
Besides providing good insulation, the two-foot-thick strawbale walls lend themselves to sculptural interpretation, especially around window openings. The flared window shapes in this home echo the window shapes at local historic ranchos and missions (see next photos). This technique minimizes glare by creating a light gradient—from the bright outdoors to the more subdued indoors.
The flared window shapes in this home echo the window shapes at local historic ranchos (like this one) and missions (see next photo).
The flared window shapes in this home echo the window shapes at local historic ranchos (see previous photo) and missions (like this one).
Nichos throughout the home reference a traditional aesthetic and draw attention to objects of beauty and function.
Nichos throughout the home reference a traditional aesthetic and draw attention to objects of beauty and function.
A ground-mounted 4.125 kW batteryless PV array—15 SolarWorld 275 W modules and 15 Enphase M250 microinverters—provides the home’s energy generation. This array was sized to meet the anticipated needs of this all-electric home but has proven to be larger than needed. An electric car could easily be charged with the surplus electricity. Once energy-storage prices drop, a battery bank would be an asset to this remote rural home when the grid goes down.
A truth window is a small opening in the wall that reveals the substrate behind the plaster—straw-clay (here) and straw bales (next photo). A tradition in strawbale houses, truth windows are a source of surprise and delight as guests get a peek inside.
A truth window is a small opening in the wall that reveals the substrate behind the plaster—straw bales (here) and straw-clay (previous photo). A tradition in straw bale houses, truth windows are a source of surprise and delight as guests get a peek inside.

The Fallgren Strawbale Home

Thermal mass, a well-insulated envelope, and a small grid-tied PV system come together to help this high-desert home generate more energy than it uses.

Home Design

Brian and Sue Fallgrens’ home, 60 miles east of San Diego,  was inspired by traditional adobe ranchos. It uses time-tested natural materials—straw, clay, and wood—to create a well-insulated, high-performance envelope. Thoughtful design by Simple Construct, a design-build company specializing in strawbale homes, included incorporating passive solar orientation to maximize cooling; shading on the south face; and a compact size in a relatively simple footprint. Coupled with careful construction—well-detailed strawbale walls, ensuring an even distribution of mass, and attention to mitigating air infiltration—these strategies help this home maintain comfortable temperatures year-round, while using little supplemental energy for heating or cooling. A 4.1 kW batteryless grid-tied PV system provides almost twice as much electricity as this home uses each year, even though every system in the home is electric—there are no fossil-fuel-powered appliances. The only combustion that takes place is in the small woodstove that uses brush collected for wildfire prevention.

The shared ethic of simplicity between the homeowners and builders led the home’s design—to try the lowest-tech solution; the most affordable off-the shelf choice; the refurbished/reclaimed option; and the passive technology first. It started by making the home as small as possible—a smaller building translates into fewer materials and less energy used.

The owners’ desire to tread lightly on the land guided many of the design decisions, as did the commitment to achieving high performance by using natural, nontoxic, low-embodied-energy materials. Opportunities to design with salvaged and repurposed furniture and to use reclaimed materials were identified, such as refurbishing an old buffet for the bathroom vanity, using wood from collapsed sheds on the property for trim, and constructing the kitchen countertops from reclaimed vintage oak planks. Human solutions—such as opening windows for ventilation rather than relying on fans—took priority over mechanical options whenever possible.

The 1,600-square-foot interior (1,900 sq. ft. exterior footprint), two-bedroom, one-bath home was completed in the spring of 2016. It is one of only 27 to have achieved the International Living Future Institute’s (ILFI) Net Zero Energy Building (NZEB) certification. ILFI, a non­profit organization promoting eco­logical design, coordinates the Living Building Challenge, a rigorous green-building standard from which the certification draws (see “NZEB Certification” sidebar for more information).

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