wine caves in the Napa Valley AVA. The cave was only 60 ft (18 m) long and was used exclusively to age the wine and to store empty barrels. In 1991, 1995, and 2001, the caves were expanded. New rooms and storage areas were added, featuring different crown heights and intriguing shapes. An octagonal room was constructed for a wine library and a round domed room was added in the complex’s center. Far Niente Winery caves now encompass about 40,000 sq ft (3,700 m²). In 1991, Condor Earth Technologies Inc. joined with Alf Burtleson on the design and construction of the elaborate Jarvis Wine Cave project. Over 45,000 sq ft (4,200 m²) of underground winery and cave space was constructed, with cave spans exceeding 85 ft (25.5 m) in width. At Jarvis, the entire winery is contained within the tunneled areas, including crushing, fermentation, barrel storage, bottling, lab, office, marketing, and hospitality areas. These caves are open for public tours by appointment. Humidity High humidity minimizes evaporation. Wine makers consider humidity over 75% for reds and over 85% for whites to be ideal for wine aging and barrel storage. Humidity in wine caves ranges naturally from 70 to 90%. In Northern California, wine barrel evaporation in a surface warehouse is on the order of 4 gallons (15.1 liters) per each 60 gallon (227 liter) barrel per year. In a wine cave, barrel evaporation is reduced to about 1 gallon (3.8 liters) per barrel per year. Since red wines are usually barreled and aged for two years, this represents a 10% gross volume loss difference. For white wines, which are barreled and aged for about one year, a 5% loss difference is realized, a significant savings. Temperature The wine industry has long considered a constant temperature between 55 °F and 60 °F (13.0 °C and 15.5 °C) to be optimal for wine storage and aging. The air temperatures in Northern California result in a uniform underground temperature of about 58 °F (14.5 °C), optimal for wine caves. A surface warehouse requires energy to cool, heat, and humidify. While the most basic wine cave can cost over $100 per sq ft to construct, reduced energy costs result in a net savings over the long term. Land use In the Napa-Sonoma wine growing region, as in many areas of California, land values are high. Non-agricultural development is often restricted. A storage warehouse reduces