NFRC Information

Thermal Properties

What is NFRC?

The National Fenestration Rating Council (NFRC) operates a voluntary program that tests, certifies, and labels windows, doors, and skylights based on their energy performance ratings. The NFRC label provides a reliable way to determine a window’s energy properties and to compare products.

Energy Performance Characteristics


The rate at which a window, door, or skylight conducts non-solar heat flow.

NFRC U-factor ratings, however, represent the entire window performance, including frame and spacer material. The lower the U-factor, the more energy-efficient the window, door, or skylight.

Solar Heat Gain Coefficient (SHGC)

The fraction of solar radiation admitted through a window, door, or skylight – either transmitted directly and/or absorbed, and subsequently released as heat inside a home.

The lower the SHGC, the less solar heat it transmits and the greater its shading ability.

Visible Transmittance (VT)

A fraction of the visible spectrum of sunlight (380 to 720 nanometers), weighted by the sensitivity of the human eye, that is transmitted through the glazing of a window, door, or skylight.

A product with a higher VT transmits more visible light.

Condensation Resistance (CR)

Condensation Resistance (CR) measures how well a window resists the formation of condensation on the inside surface.

The higher the number, the better a product is able to resist condensation. CR is meant to compare products and their potential for condensation formation.

The NFRC rating is highly determined by the glass package, therefore we can not specify the ratings by product type. The list below shows several ratings for typical products for reference.

Product – Picture
IG package U Factor SHGC VT CR
3mm CARD-366/ARG/3mm CLEAR/ARG/3mm CARD-366 0.15 0.19 0.37 75
3mm CARD-366/ARG/3mm CLEAR 0.26 0.22 0.52 63
Product – TNT
IG package U Factor SHGC VT CR
3mm CARD-366/ARG/3mm CLEAR 0.26 0.19 0.44 62
3mm CARD-366/ARG/3mm CLEAR/ARG/3mm CARD-366 0.17 0.15 0.31 73

For more detailed windows/doors information, you could locate them through the NFRC certified product directory website
*Note to select the manufacturer as Value windows & doors and corresponding window type