What Is the U Factor for Doors

U-factor is the rate at which a window, door, or skylight transmits non-solar heat flow. For windows, skylights, and glass doors, a U-factor may refer to just the glass or glazing alone.

What is a good U-factor for doors?

The qualification criteria for doors are as follows: Opaque doors must have a U-factor of 0.17 or less and there is not requirement for SHGC. Less than or equal to half-lite doors must have a U-factor of 0.25 or less and an SHGC of 0.25 or less.

What is a good U-factor?

In a cold climate a good U-factor for a window is between 0.17 and 0.39. (That’s between R-6 and R-2.5). Lower is better with U-factor–the opposite of R-value, when higher is better.