Definitions - u

U-value

U-value applies the factor of time to the heat-loss measurement. U-values measure heat that escapes per hour through a window. Windows typically have two U-values: one for the glass and one for the window, including the frame.

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Underfloor Heating

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Underground Injection

A method of land disposal in which liquid wastes are injected into known geological formations, generally at great depths.

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Unfinished Oils

All oils requiring further refinery processing, except those requiring only mechanical blending. Includes naphtha and lighter oils, kerosene and light gas oils, heavy gas oils, and residuum.

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Uniform Region

A territory with one or more features present throughout and absent or unimportant elsewhere.

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Upgradeable Product

The ability to increase a product’s performance or features without replacing the product.

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Upwelling

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Urban Heat Island
Buildup of heat in the atmosphere above an urban area. Often caused by an inversion with associated smog.


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