Measures heat transmission through a window unit due to a difference in temperature for the entire unit (frame and glazing). The smaller the U-factor, the less heat is transmitted through the window, and the better the window's insulating value. U-factors typically fall between 0.2 and 1.20.
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Renewable Energy Glossary
U-Factor
Underlayment
A thin layer of material used for waterproofing a roof underneath the top membrane or surface.
Unglazed Collector
A flat plate collector without a transparent covering, essentially an absorber plate, a pool panel
Ungrounded Conductor
A current-carrying conductor that has no connection to ground, and therefore is normally energized with reference to ground and the grounded conductor.
Ungrounded System
Those that require equipment grounding but do not have system grounding--no current-carrying conductor is connected to ground.
Uniform Solar Energy Code
Regulations relating to the proper installation of solar energy systems.
Upwind Turbine
One that has its blades on the upwind side of the tower, such that the wind hits the blades before reaching the tower.
USEC
Uniform Solar Energy Code (USEC) covers regulations relating to the proper installation of solar energy systems.
Utility Grid
The infrastructure used to generate, transmit, and distribute electricity.
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