Plymouth, Calif.—Amador Cellars in the Sierra Foothills is close to completing construction of a new 2,745-square-foot barrel room that is the first winery facility built using Energy Mass (EM) Wall construction, an energy-efficient architectural design developed and patented by Integrated Structures, Inc. (ISI) of Berkeley, Calif. ISI, an architecture, engineering and building design firm, also designed Amador Cellars’ original straw bale cellar building completed in 2003 with 22-inch-thick walls that have a high insulation R-value of R-50. The new building’s walls have about the same thickness but are designed to increase the insulation value to R-100.

Amador Cellars co-owner Larry Long is acting as the general contractor for the new building. Axiom Engineers is the mechanical engineering and refrigeration contractor. Comparing the original winery building with the new winery building, Long said, “In the end, the two buildings should look the same, but we’re adding 12 years of new wisdom and knowledge to the interior and wall construction of the new building.”

Both the old cellar and the new cellar were built using a Spar Membrane System (SMS), but the new building uses different materials and modifications for better energy efficiency. ISI president and professional engineer Gary Black describe the SMS system for the walls as similar to the design of an airplane wing, with a series of ribs (called “spars”) that connect the top surface of the airplane wing with the bottom surface of the wing, which are the “membranes,” to provide structural strength. The straw bales in the older building, and a foam core in the newer building, provide insulation and structure. A 3-inch layer of concrete on the interior wall and a 3-inch layer of concrete on the exterior wall serve as the membranes, and specially shaped spars inserted through the wall insulation structure connect and reinforce the two membranes.

In the new building, the straw bales are replaced with a poured foam core, and the previously used steel rebar “spar” rods have been replaced with fiberglass spar rods to reduce thermal heat transfer and improve energy efficiency. The fiberglass spars are also lighter weight, easier to install and provide greater strength than steel rebar.

EM Wall design and benefits
The new building uses some prefabricated components—Quad-Lock brand 2.5-inch thick, closed-cell expanded polystyrene foam panels, and high density polyethylene connector ties. The ties bridge the 12-inch space between the two parallel layers of 4-foot x 1-foot interlocking foam panels that are stacked similar to Legos as they are assembled from the ground up during wall construction. For some buildings, the 12-inch core area between the parallel foam panels is filled with poured-in concrete during wall construction. However, for Amador Cellars, instead of concrete, ISI filled the core with poured-in, expanding polystyrene foam that sets rapidly. This foam core increases the insulation R-value of the walls to R-100, significantly higher than the R-50 in the older straw bale building, and far exceeding building code requirements. 

In addition to efficient insulation, the interior walls have a radiant cooling system using coils of PEX (crosslinked polyethylene) tubing through which chilled water/propylene glycol can be circulated for cooling efficiency and temperature control. The PEX tubing is attached to a heavy duty steel mesh (4 inches x 4 inches) that runs floor to ceiling on the interior wall, then is covered with a 3-inch layer of shotcrete (sprayer-applied concrete) similar to the process used to finish wall surfaces of wine caves. The exterior walls are also covered with a 3-inch layer of shotcrete applied against a steel mesh structure.

The building will use humidification to reduce evaporative wine losses from barrels, as is commonly used in barrel-storage buildings.  With the cellar’s thick walls and insulation, and impermeability to air infiltration, wine losses from evaporation are expected to be 1% or less. Black says, “This is the same amount of wine loss reduction achieved with a true below-ground wine cave.”  Given the winery’s current average evaporative wine loss of 5%, a reduction to 1% could save wine volume with a sales value in the tens of thousands of dollars per year. (Amador Cellars produces 3,000 cases per year, according to Wines Vines Analytics.)

The EM Wall design provides potential benefits in energy efficiency and cost savings, efficient construction, and safety. The energy-efficient design will reduce utility energy costs, and can provide cost savings by allowing the use of a smaller capacity chiller for refrigeration, and also allowing a shift in energy use to off-peak hours for reduced energy pricing. Efficient construction benefits include less construction material waste, the use of prefabricated components for efficient assembly and a potentially shorter construction schedule. Safety and protection benefits include a higher than code four-hour fire rating, and the structure equals the same seismic safety strength required for hospitals and fire stations.

Other energy-efficient features include: a ventilation system using night air cooling when outdoor temperatures drop to about 53° F, a radiant heating/cooling system with PEX tubing embedded in the building’s concrete slab floor, and a solid south-side facing wall with no windows or doors to reduce heat gain on this more sun-exposed side of the building. Other walls use high-efficiency, double-paned windows with weather stripping to reduce heat gain. The new building is expected to reduce overall energy use by 40% to 60% relative to a standard barrel building, while more efficiently maintaining a constant interior temperature of 58° F.

The ceiling and roof have more traditional design elements with wood trusses made from rough-hewn Douglas fir. The ceiling will be constructed with structural insulated panels (SIPs) with an 8-inch foam core providing R-48 insulation, and the roof will be covered with corrugated metal.

Amador Cellars history and future plans
Amador Cellars was founded by Larry and Linda Long after purchasing a 22-acre vineyard property in 2000 in Amador County’s Shenandoah Valley. The estate has 16 acres planted with Zinfandel, Tempranillo, Mourvedre, Grenache, Aglianico and Sauvignon Blanc. Grapes are purchased from nearby vineyards to produce varietal Barbera, Syrah, Montepulciano, Sangiovese and Vermentino, among others.

The family’s second generation is now actively involved, with son Michael Long as winemaker, and daughter Ashley Long as assistant winemaker and marketing director. Michael discussed expected benefits of the new building for wine production. “We currently produce about 3,000 cases per year, but we’re storing about 6,000 cases in barrels at any given time,” he said. “This new building should allow us to double our barrel-storage capacity, and we can potentially grow to 5,000 cases per year production.” The winery’s focus is on direct sales. The original cellar building is at capacity for barrel and case storage, so additional onsite storage will be a benefit. 

The Longs plan to have a small lab room in the new building, and a covered concrete pad on the north (shaded) side of the building will provide more space for barrel cleaning and filling operations. The area between the old and new buildings will become an enclosed courtyard to expand visitor facility space for picnicking, tastings and events.