PERFORMANCE: Codes & Standards

International Energy Conservation Code (IECC)

IECC Climate Zone Map

2012 | 2009 | 2006

2012 International Energy Conservation Code
The 2012 IECC is the latest version of the International Energy Conservation Code. Like all versions of the IECC, its prescriptive path sets U-factor and SHGC requirements and fenestration area limits. The total building performance path allows greater design flexibility but requires detailed energy modeling. Regardless of the chosen compliance path, fenestration must not exceed mandatory air leakage limits. The 2012 IECC requires replacement windows to comply with the requirements set for new construction. The requirements apply whether it is a full window replacement or just sash and glazing replacement.

2012 IECC Prescriptive Fenestration Requirements
Climate Zone 1 2 3 4 & 5 6 7 & 8
Vertical Fenestration
Maximum U-factor
Fixed fenestration 0.50 0.50 0.46 0.38 0.36 0.29
Operable fenestration 0.65 0.65 0.60 0.45 0.43 0.37
Entrance doors 1.10 0.83 0.77 0.77 0.77 0.77
Maximum SHGC (no overhanging projections or width of projection is less than ¼ the height from window sill to underside of projection)
All vertical fenestration 0.25 0.25 0.25 0.40 0.40 0.45
Skylights
Maximum U-factor 0.75 0.65 0.55 0.50 0.50 0.50
Maximum SHGC 0.35 0.35 0.35 0.40 0.40 Any

These requirements are adjusted where shading from permanent projections is provided and for certain daylighting designs.

The maximum SHGC can be increased if any permanently attached shading device has a projection factor (PF) greater than 2.0, where the width of the shading device is more than ⅕ the height from the sill to the underside of the shading device. The increase in SHGC is dependent on orientation. Glazing oriented to the north is less than that oriented in the other 3 orientations.

Unless a building is designed for daylighting, the prescriptive path limits vertical fenestration area to 30% of the gross above-grade wall area. If automatic daylighting controls are installed in daylight zones, vertical fenestration area of up to 40% is permitted in Climate Zones 1 through 6. This would also require that at least 50% of the conditioned floor area is within a daylight zone and that the fenestration VT is at least 1.1 times the SHGC.

Skylight area is limited to 3% of the gross roof area, but can be expanded to 5% of the roof area if automatic daylighting controls are installed in daylight zones. In some larger spaces with high ceilings, the code requires a minimum skylight area for daylighting.

Mandatory air leakage limits depend on the fenestration type. For windows, sliding doors and most skylights, the maximum air leakage rate is 0.2 cfm/ft2, or 0.3 cfm/ft2 if tested at 6.24 psf.

2012 | 2009 | 2006

2009 International Energy Conservation Code
Like all versions of the IECC, the 2009 IECC has a prescriptive path that sets U-factor and SHGC requirements and fenestration area limits. The total building performance path allows greater design flexibility but requires detailed energy modeling. Regardless of the chosen compliance path, fenestration must not exceed mandatory air leakage limits.

The prescriptive path limits vertical fenestration area to 40% of the gross above-grade wall area and skylight area to 3% of the gross roof area.

2009 IECC Prescriptive Fenestration Requirements
Climate Zone 1 2 3 4 except Marine 5, 6 & Marine 4 7 & 8
Vertical Fenestration
Maximum U-factor
Framing materials other than metal with or without metal reinforcement or cladding
Non-metal frame 1.20 0.75 0.65 0.40 0.35 0.35
Metal framing with or without thermal break
Curtain wall/storefront 1.20 0.70 0.60 0.50 0.45 0.40
Entrance door 1.20 1.10 0.90 0.85 0.80 0.80
All other metal frame 1.20 0.75 0.65 0.55 0.55 0.45
Maximum SHGC
Projection Factor <0.25 0.25 0.25 0.25 0.40 0.40 0.45
Projection Factor <0.25 0.33 0.33 0.33 Any Any Any
Projection Factor <0.25 0.40 0.40 0.40 Any Any Any
Skylights
Maximum U-factor 0.75 0.75 0.65 0.60 0.60 0.60
Maximum SHGC 0.35 0.35 0.35 0.40 0.40 Any

Mandatory air leakage limits depend on the fenestration type. For windows, sliding doors and most skylights, the maximum air leakage rate is 0.3 cfm/ft2.

2012 | 2009 | 2006

2006 International Energy Conservation Code
Like all versions of the IECC, the 2006 IECC has a prescriptive path that sets U-factor and SHGC requirements and fenestration area limits. The total building performance path allows greater design flexibility but requires detailed energy modeling. Regardless of the chosen compliance path, fenestration must not exceed mandatory air leakage limits.

The prescriptive path limits vertical fenestration area to 40% of the gross above-grade wall area and skylight area to 3% of the gross roof area.

2006 IECC Prescriptive Fenestration Requirements
Climate Zone 1 2 3 4 except Marine 5, 6 & Marine 4 7 & 8
Vertical Fenestration
Maximum U-factor
Framing materials other than metal with or without metal reinforcement or cladding
Non-metal frame 1.20 0.75 0.65 0.40 0.35 0.35
Metal framing with or without thermal break
Curtain wall/storefront 1.20 0.70 0.60 0.50 0.45 0.40
Entrance door 1.20 1.10 0.90 0.85 0.80 0.80
All other metal frame 1.20 0.75 0.65 0.55 0.55 0.50
Maximum SHGC
Projection Factor <0.25 0.25 0.25 0.25 0.40 0.40 0.45
Projection Factor <0.25 0.33 0.33 0.33 Any Any Any
Projection Factor <0.25 0.40 0.40 0.40 Any Any Any
Skylights
Maximum U-factor 1.60 1.05 0.90 0.60 0.60 0.60
Maximum SHGC 0.40 0.40 0.40 0.40 0.40 Any

For skylights with plastic, different requirements apply.

Mandatory air leakage limits depend on the fenestration type. For windows, sliding doors and most skylights, the maximum air leakage rate is 0.3 cfm/ft2.

2012 | 2009 | 2006

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