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2009 IECC
Chapter 3: Climate Zones
Regulatory Requirements (303.1.3)
U-Factors and Solar Heat Gain Coefficient (SHGC) of fenestration products (windows, doors and skylights) shall be determined in accordance with NFRC 100 and NFRC 200 respectively, by an accredited, independent laboratory, and labeled and certified by the manufacturer. Products lacking such labels, shall be assigned default values (Table 301.1.3: 1, 2). The default values typically do not give full credit for energy efficient performance.
Chapter 4: RESIDENTIAL ENERGY EFFICIENCY
Fenestration Air Leakage( 402.4.4. - mandatory):
Air leakage requirements are set at 0.3 cfm/sf for windows and sliding doors (cubic feet per minute per square foot of window area) and 0.5 cfm/sf for swinging doors. Fenestration systems must be tested in accordance with NFRC 400 or AAMA/WDMA/CSA 101/I.S.2/A440, by an accredited, independent laboratory and listed and labeled by the manufacturer. Exceptions: Site built windows, skylights and doors.
Prescriptive requirements (402.1.1) - by climate zone are shown below:
Table 402.1.1 in the 2009 IECC
| Climate Zone |
Fenestration U-Factor |
Fenestration SHGC |
| 1 |
1.20 |
0.30 |
| 2 |
0.65 |
0.30 |
| 3 |
0.50 |
0.30 |
| 4-8 |
0.35 |
None |
Click here to see the corresponding climate map.
Glazed Fenestration Exemption 402.3.3.)
Up to 15 square
feet (1.4m2) of glazed fenestration per dwelling unit shall be
permitted to be exempt from U-factor and SHGC requirements
in Section 402.1.1. This exemption shall not apply to
the U-factor alternative approach in Section 402.1.3 and the
Total UA alternative in Section 402.1.4.
Total UA alternative (402.1.4)
If the total building thermal envelope UA (sum of U-factor times assembly area) is less than or equal to the total UA resulting from using the U-factors in Table 402.1.3 (see below, multiplied by the same assembly area as in the proposed building), the building shall be considered in compliance with Table 402.1.1 (above). The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials. The SHGC requirements shall be met in addition to UA compliance.
Table 402.1.3 in 2009 IECC
| Climate Zone |
Fenestration
U-Factor |
Skylight U Factor |
| 1 |
1.20 |
0.75 |
| 2 |
0.65 |
0.75 |
| 3 |
0.50 |
0.65 |
| 4-8 |
0.35 |
0.60 |
Simulated Performance Alternative (405.2)
Mandatory requirements. Compliance with this section
requires that the mandatory provisions identified in Section
401.2 be met.
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