Replacement Windows, Vinyl Padio Doors & Vinyl Siding    

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U

U-Factor:  See U-Value.

Unison Lock:  A casement locking system which secures the window at two locking points by operation of one handle.

U-Value:   Amount of heat transferred through a material. It is expressed in units of Btu/hr-sq ft-°F (W/sq m-°C). Values are normally given for NFRC/ASHRAE winter conditions of 0° F (18° C) outdoor temperature, 70° F (21° C) indoor temperature, 15 mph wind, and no solar load. The U-factor may be expressed for the glass alone or the entire window, which includes the effect of the frame and the spacer materials. The lower the U-factor, the greater a window's resistance to heat flow (or the slower the heat flow) and the better its insulating quality.

UV Block:  The percent of ultraviolet rays blocked from being transmitted through the glass. The higher the number the lower the percentage of ultraviolet rays transmitted through the window.

Ultraviolet Light (UV):   The invisible rays of the spectrum that are outside of the visible spectrum at its short-wavelength violet end. Ultraviolet rays are found in everyday sunlight and can cause fading of paint finishes, carpets, and fabrics.