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Measuring Performance: ENERGY STAR® Most Efficient Program

  • Energy Star Zones

    The ENERGY STAR Most Efficient designation recognizes the most efficient products among those that qualify for the ENERGY STAR. These exceptional products represent the leading edge in energy efficient products for a given year.

    Criteria

    Windows must be ENERGY STAR qualified consistent with applicable ENERGY STAR Partner Commitments and the requirements set forth in the latest version of the ENERGY STAR Program Requirements Eligibility Criteria for Windows Version 6.0. Product performance (U-factor and SHGC) must be certified by an EPA-recognized certification body.

    Windows must be independently certified to meet the North American Fenestration Standard/Specification (NAFS) with a Performance Grade ≥15. Acceptable certification bodies shall be accredited to operate in accordance with ISO/IEC Guide 65, by an accrediting body that is a signatory to the International Accreditation Forum Multilateral Recognition Agreement that operates in accordance with ISO/IEC 17011. NAFS certification does not require an EPA-recognized certification body.

    View all ENERGY STAR Most Efficient 2017 Recognition Criteria

Northern Zone Required Properties (mostly heating)
U-factor Solar Heat Gain Coefficient (SHGC) Visible Transmittance (VT) Air Leakage (AL)
Windows: U≤0.20 Windows: SHGC≥0.20
Windows: VT=No Requirement
Windows: AL=As per NAFS
North/Central Zone Required Properties (heating & cooling)
Windows: U≤0.20 Windows: SHGC≤0.40 Windows: VT=No Requirement Windows: AL=As per NAFS
South/Central Zone Required Properties (heating & cooling)
Windows: U≤0.20 Windows: SHGC≤0.25 Windows: VT=No Requirement Windows: AL=As per NAFS
Southern Zone Required Properties (mostly cooling)
Windows: U≤0.20 Windows: SHGC≤0.25 Windows: VT=No Requirement Windows: AL=As per NAFS

U=U-factor in Btu/hr-sf-°F
SHGC=Solar Heat Gain Coefficient in fraction of incident solar angle
VT=Visible Transmittance in fraction of incident visible radiation
AL=Air Leakage in cfm/sf