Energy & Cost

• Energy
• Peak Demand
• Carbon
• Cost

Human Factors

• Daylighting
• Glare
• View
• Thermal Comfort
• Natural Ventilation

Codes & Standards

• IECC
• ASHRAE 90.1
• ASHRAE 189 & IgCC
• North American Fenestration Standard
• Component Modeling Approach

USEFUL INFORMATION

International Code Council

IECC Overview

International Energy Conservation Code (IECC)

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.

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 solar heat gain coefficient.

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.

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

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.

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.

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