EFCO Corporation is a leading manufacturer of architectural aluminum window, curtain wall, storefront and entrance systems for commercial architectural applications. Headquartered in Monett, Missouri, EFCO's mission is to be the most trusted supplier in commercial architecture.  EFCO seeks to provide customers with the highest level of quality, innovation, value, and service.

With the dedication of the EFCO team and backed by the support of Apogee Enterprises, Inc., an industry leader in commercial technology, innovation and customer satisfaction, you can count on EFCO to provide the best fenestration solutions and quality service for commercial construction. Today, and in the future.

View EFCO's Corporate Overview video






 EFCO Product Recommendations

Developed to be IBC 2021 & IECC 2021 Compliant for Climate Zones 5 & 6 and MA Stretch Energy Code

The following EFCO window, storefront and curtain wall recommendations have been developed to assist owners, architects and contractors in the selection and specification of EFCO commercial fenestration solutions that meet the requirements of the IBC 2021, IECC 2021 for the Northeast (i.e., Climate Zones 5 & 6) and MA Stretch Energy Code.   Appropriate use and application of these recommendations will vary based on performance considerations and environmental conditions unique to each project and, therefore, do not represent the final opinion or recommendation of PACE Representatives or EFCO.  Contact PACE Representatives to develop a custom fenestration basis of design (BOD) package to meet your project specific performance requirements and design conditions.

SeriesDepthSightlineThermal Performance*
(center of glass U-Factor)
 Impact Ballistic  Blast  Notes
 325X3 1/4"2 1/8"0.340.290.260.19<0.17YesNoNo Applied grid available.
FX323 1/4"1 1/4"0.380.330.30NA<0.21NoNoNo 
590X3 1/4"1 1/2"0.360.310.27NA<0.19NoNoNo Historic steel replica window
 325X 3 1/4"3 5/16"0.410.380.350.30<0.28YesNoNo Applied grid available
590X3 1/4" 1 1/2"0.460.420.38NA<0.32NoNoNo Historic steel replica window
WV4303 1/4"7/8" 0.440.400.35NA<0.28NoNoNo Project-out vent for storefront & curtain wall
HX323 1/4"4 3/16"0.420.380.35NA<0.28NoNoNo Single Hung
SX454 1/2"4 1/2"0.440.400.360.31<0.30NoNoNoThermal performance based on premium model

 * Based on NFRC 100 gateway size and configuration for operation shown.

Center of Glass (COG) Summary:
U-0.30 = 1" IGU w/ air fill and Low-E on #2 surface
U-0.24 = 1" IGU w/ argon fill and Low-E on #2 surface
U-0.20 = 1" IGU w/ argon fill and Low-E on #2 and #4 surfaces
U-0.12 = 1 5/8" IGU w/ argon fill and Low-E on #2 and #4 surfaces
U-0.075 = 5/8" VIG w/ Low-E on #2 surface 


Industry Insights

Code Requirements: (per IECC 2021 & MA Stretch Energy Code)

The prescriptive thermal performance requirements (i.e., U-Factor) for vertical fenestration systems are indicated in Table C402.4 of the IECC 2021.  Frame material is no longer taken into account and the requirement is based on your climate zone and fenestration type.  (e.g., Fixed, Operable or Entrance Doors)

Climate Zone  5 and Marine 4              6           MA Stretch Code
Vertical Fenestration
Fixed Fenestration0.360.340.30
Operable Fenestration0.450.420.32
Glazed Wall SystemNANA0.25

Prescriptive compliance is only allowed with a vertical fenestration area less than or equal to 30% of the gross above-grade wall area.  Prescriptive compliance is allowed up to not more than 40% of the gross above-grade wall area if certain minimum floor areas are in the daylight zone and daylight responsive controls are incorporated.

U-Factors of fenestration systems (e.g., windows) shall be determined by an accredited, independant laboratory in accordance with either NFRC 100 or ANSI/DASMA 105 AND labeled by the manufacturer.  Products lacking a U-Factor label shall be assigned a default U-Factor per IECC 2021 Tables C303.1.3(1)-(3).

The air leakage of window assemblies shall be a maximum of 0.20 CFM/FT2 per AAMA/WDMA/CSA101/I.S.2/A440 or NFRC 400.  The maximum rate of 0.30 CFM/FT2 shall be permitted when tested in accordance with AAMA/WDMA/CSA101/I.S.2/A440 at 6.24 psf (300Pa).


Additional Resources:

Whole Building Design Guide - Windows

National Fenestration Rating Council

Wind Speed Calculator