Rammed earth homes aren’t a new fad. In fact, rammed earth construction was taking place in 2,000 B.C. in Mesopotamia and ancient China.

Parts of the Great Wall of China are built of rammed earth and in parts of China, Africa and the Middle East dwellings are still being occupied that are centuries old.

Rammed earth construction consists of mixing soil with cement, adding water to get proper moisture content and compacting it between wood forms. The construction is labor intensive because only about eight inches of soil can be compressed between the forms at one time. It is similar to building a cast-in-place concrete wall. Electrical, plumbing, window and door openings are installed and blocked out within the framework.

In another method, called PISE (pneumatically impacted stabilized earth), the soil materials are mixed and sprayed pneumatically against a plywood form.

Lance Emerson has lived in a rammed earth home on Old Sonoma Highway in the Carneros region of Napa for nine years.

“The walls are 24 inches thick,” said Emerson. “The floors have radiant heating which can be controlled in individual rooms. Because of the thickness of the walls, the inside temperature stays consistent. In the winter, the walls absorb heat during the day and release it at night. We’re a family of four and last winter we didn’t have a heating bill over $60 a month. In the summer, we open the windows at night and close them in the morning. It stays at 65 degrees.”

Emerson’s home, constructed in 1989, is a cozy 1,554 square foot abode with one bedroom, an office, living room, kitchen and two bathrooms. Except for the deep window ledges, the rooms, including the kitchen and baths, look like those in any conventionally constructed home. One thing that is different is the quiet.

“You can’t hear road noises in here,” said Emerson. “A previous owner was a cellist who practiced in the kitchen and liked the house for its acoustic qualities. I think there’s a feeling of energy in the house. Old World energy.”

The perimeter walls do have an Old World look to them, with a patina of natural clay. Interior walls are not load bearing, so homeowners have the flexibility to change the configuration of the rooms.

Rammed earth builders have adopted green building standards. Green building, also known as sustainable or environmental building, reduces operating costs by using less energy, improves occupant health due to indoor air quality and reduces environmental impact.

Stanford engineer David Easton, whose firm Rammed Earth Works has completed over 100 rammed earth projects in Napa, Sonoma and Mendocino counties, designed the Old Sonoma Highway home.

“Earth is one of the greenest of building materials,” said Easton. “It involves less processing and shorter transportation routes than sawn lumber. As a monolithic wall it uses none of the manufactured materials common to a composite wall, such as fiberglass, plastic wrap, siding, wallboard, or paint. As a thick wall, it stores solar heat to reduce the amount of non-renewable energy needed to maintain comfortable indoor temperatures. It requires no exterior painting or other maintenance, and best of all; well-built walls of rammed earth can be expected to last for centuries. If the objectives of the green building movement are resource conservation, non-toxicity and durability, then rammed earth is surely one of the best of sustainable solutions. In the wine country, rammed earth and PISE continue to grow in popularity.”

How do rammed earth structures fair during earthquakes?

“In seismically active regions such as California, rammed earth and PISE walls are engineered following the same principles used for other types of masonry and concrete,” said Easton. “Reinforcing steel is embedded within the rammed earth, allowing the wall to develop the tensile strength necessary to respond to lateral forces. Due to the relative unfamiliarity of engineers and inspectors with modern rammed earth, all designs are subject to the highest imaginable safety factors.”

Rammed earth structures are fireproof, insect resistant, maintenance free and the walls do not emit toxic gases. Depending on the design, the site and special features, such as seismic reinforcement, rammed earth homes generally cost 5 percent to 10 percent more than conventional stick homes.

“How much a rammed earth house costs is a factor of the design and the finish, not whether the walls are earth, wood, stone or straw,” said Easton. “Walls on average account for less than 20 percent of the overall construction budget.”

There are quite a few rammed earth projects around the Napa Valley. Other Easton projects are the Elm Street bungalows in Napa.

Rutherford’s Long Meadow Ranch Winery is one of the largest rammed earth structures in North America. Designed by William Turnbull, the walls were constructed out of the soil excavated when the wine caves were dug. It uses no mechanical heating or cooling and received a commercial design award from the American Institute of Architects.

Emerson will soon give up his treasured home. Because of his business, importing and manufacturing Mexican hacienda features such as pillars and tiles, he spends half the year in Mexico and he has put his rammed earth home on the market. He said he’d miss it.

“It’s simple and really comfortable,” said Emerson.