Definitions for "U-value"
Rate of heat flow-value through the complete heat barrier, from room air to outside air. The lower the U-value, the better the insulating value.
A measure of air-to-heat transmission (loss or gain) due to the thermal conductance and the difference in indoor and outdoor temperatures. As the U-value decreases, so does the amount of heat that is transferred through the glazing material. The lower the U-value, the more restrictive the fenestration product is to heat transfer. Reciprocal of R-value.
The reciprocal of R-value. The rate of heat transmittance through a material, or assemblage, of one square foot in area, measured in BTUs per hour, and based on an indoor-outdoor temperature difference of 1 degree F (BTU/hr-square foot-degrees F). See R-value.