When he started planning a new winery for Château Maris in southern France's Languedoc region, Robert Eden looked at natural options such as stone, rammed earth and even straw. What he ended up choosing was something that, at least in certain crowds, elicits quips about marijuana—hemp. But it's no joke: The new Maris winery is built almost entirely from large, sturdy "bricks" of organic hemp straw. Those bricks not only reduced carbon emissions from construction, they also continue to capture carbon dioxide from their surroundings.
"This is the first winery in the world like this," claimed Eden of the 9,000-square-foot building, finished just in time for the 2012 harvest after eight years of work, five of them devoted to planning and research. "We're in unknown waters here."
Hemp—low-THC varieties of the cannabis plant with negligible psychoactive properties—has been used to build houses in Australia, Europe, South Africa and, just recently, in the United States, even though growing it and producing it industrially is illegal in many states. However, hemp is still rare for larger buildings. Eden hopes that other wineries can learn from Maris and use hemp bricks for future construction.
What inspired his choice? "As farmers, we are aware of climate change being a big game-changer for us," said Eden. An Englishman who has long lived in France, Eden took over Maris in 1996 with American business partner Kevin Parker, the former global head of Deutsche Asset Management and now CEO of New York-based Green Partners, a private investment firm investing in sustainable business and green energy.
With the goal of creating "grand cru-level" wines from La Livinière in the Minervois appellation, the partners converted the property to biodynamic farming; the entire estate is now certified by Demeter, Biodyvin, Ecocert and under the USDA's National Organic Program. In 2003, dissatisfied with the winery space they were using, they decided to create a new home for Maris. "We wanted to have a building that respects what we are doing in the vineyards in every way," said Eden, a vocal biodynamics advocate. "We wanted the building to require as little energy as possible to function, yet retain a sane, healthful ambiance. And the whole thing had to be practical."
In choosing materials, the Maris team looked at overall environmental impact, including where the materials came from, how they were transported and how they were made. They found the most ideal material in straw from fast-growing hemp, which does not require any irrigation or fertilization and whose rapid root growth helps control soil erosion. Hemp fibers can be used to make clothes and rope, the leaves to make paper and the seeds for oil—the straw is essentially a byproduct. In Europe, hemp is partly subsidized, and France has extensive plantings in the area around Toulouse, so the material was both cost-effective and close to the winery, reducing the carbon footprint.
To make the bricks, lime was added to the straw to harden it; the chemical transformation into a limestone carbonate captures and sequesters carbon dioxide over many years. The mixture was molded into bricks that are very light—only 33 pounds for a nearly two-foot thick brick—and easy to transport.
French regulatory authorities wouldn't permit them to build an entire facility out of a non-standard material—getting approval could have taken 10 or more years, Eden estimated—so workers laid the bricks, clamped together with rivets, but left holes through which they put a frame of untreated wood from certified sustainably managed forests. (Basically, almost the entire building is biodegradable, though Eden says the hemp bricks could last for a century or more.) Acknowledging that it was difficult to precisely measure, Eden said that they calculated that the plant-based building materials had consumed 44 kilos of CO2 per square meter, and that the carbonation process will continue to capture more over the next 20 to 25 years.
Eden is particularly curious to see what will happen with all the CO2 produced by fermentation. When the bricks carbonate, they change colors slightly and become very hard. "Today if you go up to the walls, it looks like cement, but you can touch the exposed parts and feel the brick is still soft," he said. "So we can measure how quickly the hardness increases."
Hemp is known as a good insulator, along with being a "breathable" material and having good acoustic properties. Maris does not have an air-conditioning system, but Eden expects the interior to remain about 54° to 63° F year-round. To provide an extra buffer against extreme temperatures, the building was constructed with two exterior walls, with an air tunnel between them, and a duct in the roof of the cellar to allow the winemaking team to increase airflow. "Fermentations produce a lot of heat, so if we find the walls aren't enough we can help," Eden explained. Extensive testing of this setup—by building smaller hemp-brick huts, both exposed to the weather and covered so that hot or cold air could be injected into the enclosure—found that outside temperatures could range from 21° to 93° F and the interior temperatures would stay fairly stable, with a total variation of no more than 18° F.
Château Maris is in the process of applying for the U.S. Green Building Council’s LEED certification, hoping to earn Platinum, the highest level. Along with the novel hemp construction, Maris takes advantage of many other green building practices: The 15,000-case winery was built into the hillside, with a soil-topped roof planted with local vegetation that needs little water. To minimize water consumption, the winery collects rainwater and recycles its gray water by filtering it through a natural pond system. Low-consumption LEDs are used for all the lighting. Future plans call for a windmill and solar panels to provide all of the winery's power and the addition of a hemp-based visitor center and a garden.
From the estate vineyards, Eden produces a range of very good to outstanding red varietals and blends from Syrah, Grenache and Carignane, along with a white from Grenache Gris. The wines are made with native yeasts, in custom-made tanks—wood, wide concrete or egg-shaped concrete—to avoid the use of any electrically conductive materials (which biodynamics practitioners believe disrupt energy flow). The wines are left unfined and unfiltered, and packaged in lightweight, recycled glass bottles, with recycled paper labels. Three of the wines help fund charities, with donations of $1.50 from each bottle sold going to the Jane Goodall Institute, Rainforest Foundation or International Polar Foundation.
Reflecting back on the long path to the winery's completion, Eden noted that he could have opted for an existing product that was a mix of hemp and concrete, but didn't want to use it because of the cement's higher carbon footprint. "My fanaticism in wanting to respect the environment made me push to go the whole way. If something is going to be the first, you may as well pull it as far as you can. Hopefully you're making the mistakes for others to avoid."
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