BE5: Glazing Performance

(1-3 points)

PURPOSE

Reduce heat gain and loss through the building envelope glazing by meeting the prescriptive glazing requirements.

CRITERIA

Specify and install glazing that has better than energy code-required maximum weighted-average U-Factors for all vertical glazing, including doors with greater than 50% glass. Effective SHGC of less than or equal to 0.25 meets or exceeds ASHRAE 90.1-2013 through glazing only or glazing plus projection factor. Performance Badge projects must earn Options A, B and C.

Select all applicable options:

A. Maximum glazing weighted-average U-Factor of 0.33 (2 pts)

B. Maximum glazing weighted-average SHGC is < 0.25 (4 pts)

*See BE 6.1: SHGC Multiplier for Permanent Projections below. See ASHRAE 90.1-2013, Table 5.5.4.4.1.

VERIFICATION 

• Construction Documents indicate U-factor for all glazing components 
• Site Inspection – Leave NFRC label on glazing OR provide photographs 
• For Site fabricated glazing provide Certificate of Compliance

DEFINITIONS

Solar Heat Gain Coefficient (SHGC) – the ratio of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. SHGC is expressed as a number between zero and one. The lower a window’s solar heat gain coefficient, the less solar heat it transmits.

Projection Factor (PF) – the ratio of the horizontal depth of the external shading projection divided by the sum of the height of the fenestration and the distance from the sum of the height to the bottom of the farthest point of the external shading projection, in consistent units.

RESOURCES

National Fenestration Rating Council www.nfrc.org

ASHRAE 90.2-1013 www.ashrae.org