What is the default U-factor for a metal framed, double paned window according to code?

The default U-factor for a metal framed, double paned window, as specified by energy efficiency codes, is recognized as 0.60. The U-factor measures the rate of heat transfer and indicates how well a building element—like a window—insulates. For metal-framed windows, which typically have lower thermal resistance compared to more insulated framed options, this U-factor signifies a standard assumption in energy modeling and compliance with building codes.

A U-factor of 0.60 may be established based on typical construction practices and material characteristics, leading to its designation as a default value for types of windows like the one described. Understanding this value is crucial for HERS raters when calculating energy performance and assessing compliance with energy efficiency regulatory frameworks.