Valuing Wind Machines

Valuing Vineyard Wind Machines

There are many risks to growing grapes in Napa County, including the danger of frost damaging new growth that would otherwise mature to produce the valuable crop. To protect against frost, grape growers use several methods, including

  • Propane-fired orchard heaters which warm the air
  • Sprinkler frost protection, which protects the vines by coating them in ice at a temperature above the danger point
  • Wind machines, which keep the air circulating so that the coldest air does not settle on the vines

Wind machines have a powerful motor, powered by gasoline, diesel or propane; a propeller to move the air; and a support structure that can either be at ground level or consist of a tower. Wind machines cost in the range of $12,000 for a reconditioned model to $60,000 or more for a new model. Once installed, wind machines in Napa County stay in one place, even though some models are mounted on skids. Owners of wind machines keep them well maintained so that they have a long, useful life.

Wind Machines as Fixtures

Napa County values sprinkler frost protection systems as real property structures and orchard heaters and wind machines as fixtures. Structures have a Proposition 13 base-year value and are subject to an inflationary adjustment and reassessment upon change of ownership. Fixtures do not have a base-year value and are not subject to an inflation factor. Instead, fixtures are valued annually, based on original cost to which a valuation factor is applied that accounts for the age of the machine and for changes in the value of a dollar over time. The valuation factor table is based on a twenty-five year life for wind machines. Acquisition cost adjusted by a valuation factor represents a good estimate of the current market value of the fixture.


Property owners can assist our staff in ensuring that their wind machines are correctly assessed. If you have one or more wind machines on your property, please check your 2022-2023 tax bill for a value in the fixture column. If there is no value in the fixture column, please contact our office so that we can apply the appropriate assessment procedure to your wind machine(s).

More Information

Should you have any questions please contact Napa County Assessor-Recorder-County Clerk John Tuteur at 707-253-4459 or by email John.