Silver Oak Cellars Uses MeeFog Humidification to Reduce Wine Evaporative Losses

Agriculture

Silver Oak Cellars, Oakville, California, USA

You can visit your local Trader Joe’s and pick up a bottle of Charles Shaw wine (also known as Two Buck Chuck) for less than three dollars. Or you can make a pilgrimage to California’s Napa Valley, view the vineyards, meet the winemaker, and spend a hundred times that amount on a bottle of premium vintage. The difference between the two lies in the careful attention to details required to produce a premium product.

Since 1972, Silver Oak Cellars in Oakville, California has been producing premium quality Cabernet Sauvignon. To maintain the quality of the wine and minimize evaporative losses, Silver Oak uses a MeeFog™ humidification system in all of its barrel rooms. Silver Oak ages its wine for about 25 months in barrels made from American oak.

Challenge:

Silver Oak Cellars needed to control humidity in their barrel rooms to prevent oak barrels from drying out. Dry barrels lead to wine soaking through the wood and evaporating, causing significant losses given the wine’s value of around $100/liter.

Solution:

Installing a MeeFog humidification system with fogging nozzles near the ceiling of each of the barrel rooms allowed the winery to accurately control the temperature and humidity in the rooms during wine production, decreasing evaporation loss and reducing the need to top off barrels.

Humidity Control for Wineries

The control of temperature and relative humidity (RH) within a wine cellar is an indispensable element to regularly produce high-quality products.

Historically, winemakers have found that the ideal conditions to age wine is between 45°F and 65°F, with a relative humidity between 50 and 80 percent. The ideal conditions differ slightly based on certain winemakers, but 55°F and 70 percent relative humidity is considered ideal, nearly perfect by many.

As it turns out, the ideal conditions for wine aging were discovered centuries ago. Through years of trial and error, it was found that the best quality wine was aged in rooms below ground level, typically in the basement of a castle.

Winemakers didn’t know it at the time but the reason why it aged nearly perfectly, is because most wine cellars in Europe had an indoor climate close to 55°F at 70 percent relative humidity.

“Originally the winemaker tried six or eight different brands of barrels with different types of wood,” says Greg McClain, Maintenance Manager for Silver Oak Cellars. “He liked the way the wine aged in American oak barrels tasted, so we have been using them from day one. A few other wineries are starting to use American oak as well.”

During this time, unless the humidity is controlled, the oak will dry out, allowing some of the wine to soak through the wood and evaporate. In addition, the wood shrinks as it dries, loosening the seals between the staves making up the barrel, increasing the loss of wine. With the wine selling for around $100/liter, any loss is costly. To address this issue, Silver Oak installed a MeeFog™ humidification system at both Oakville and Geyserville to maintain the moisture in all the barrel rooms.

“Mee makes a simple, automatic, self-contained system to control humidity during the aging process,” says Greg McClain. “It is hung from the ceiling and out of the way, so when we bring tours through the facility everything looks nice.”

Instillation

Silver Oak has one MeeFog system in place at its 65,000-square-foot showcase facility in Oakville and a second one at its winery in Geyserville. The MeeFog system in Oakville has a single variable speed pump to humidify all four barrel rooms. Each of the barrel rooms has a sensor to monitor the humidity, and when it goes out of range, the pump will start up and run at the speed needed to bring the humidity back to the set point.

“We have 8-inch-thick concrete walls in the barrel room,” says Greg McClain, Maintenance Manager for Silver Oak Cellars. “Once the temperature and humidity reach the set point in there, it stays pretty constant unless we are opening and closing the roll-up doors and going in and out a lot.”

The pump sends up to 0.6 gallons per minute of 1000 psi water through stainless steel tubing to a set of 12 nozzles spaced throughout the barrel room near the ceiling. The impaction pin nozzles convert that water into a fog of minute droplets which quickly evaporate, so there is no problem with water pooling or mildew growth.

“We stack our barrels fairly high here so they are close to the nozzles,” says McClain. “Sometimes the barrels on the top row get a little moist, but with the cooling fans running they dry right up.”

There was one other element that Silver Oak needed to put in place: installing a reverse osmosis system to reduce dusting. The filters catch any particles and remove them from the water so they wouldn’t clog the fogging nozzles, but when the water evaporates, the silica precipitates as a fine white powder on the barrel rack surfaces.

Cost-Benefit Analysis:

With the MeeFog system in place, Silver Oak’s staff spent less time opening and topping off the barrels. The real savings, though, come from preventing the evaporation of the premium wine Silver Oak produces. McClain says that the MeeFog system does its job well and without a lot of attention from the maintenance staff. “It’s a low-maintenance system. We just have to change the filters occasionally and service the pump every two years.”

“Keeping the humidity at the correct level in the barrel room helps prevent evaporation so we have to do less topping,” says McClain. “If we didn’t have the MeeFog humidification system in there we would need to be topping the barrels every month and would be losing a lot of wine through evaporation. Now we are down to topping the barrels once every four to six months.” -— Greg McClain, Silver Oaks Cellars Maintenance Manager

Resources:

Learn more about humidity for wine production and storage.

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