Add the Following Definition to Section 202

Proposed Draft for Skylights with Daylighting proposal for 2007 ICC Supplement

1. Add the following definitions to Section 202

SECTION 202 GENERAL DEFINITIONS DAYLIT AREA UNDER SKYLIGHTS. The area underneath the skylight that retains at least 70% of the daylight luminance directly under the skylight. The daylit area shall be taken as the sum of the following: 1. The horizontal projection of the outline of the skylight glazed opening onto the floor directly beneath the skylight, 2. Additional areas around the perimeter of the area defined in Item 1 above. The width of these areas shall be the lesser of the following: a. 70% of the ceiling height, b. 50% of the distance to the edge of the nearest skylight.

AMBIENT LIGHTING. Luminaires that provide ambient diffuse lighting in a space. Ambient lighting includes, but is not limited to, lighting by linear fluorescent luminaires (direct, indirect or direct/indirect), high bay or low bay luminaires. Lighting not considered ambient lighting includes: emergency lighting, electric signs, display lighting, decorative lighting (such as chandeliers), theatrical lighting, or wall sconces less than 150 W.

MULTI LEVEL DAYLIGHTING CONTROLS. Systems that reduce the lighting power draw in a series of at least two levels or by continuous dimming in response to availability of daylight within the interior space.

HAZE VALUE. The ratio of diffusely transmitted light to total light transmitted.

2. Revise SECTION 502

BUILDING ENVELOPE REQUIREMENTS 502.5 Skylights. Skylights located in the building envelope shall be limited to 3 percent of the gross roof assembly area and shall have a maximum thermal transmittance (U-factor) and SHGC of the skylight assembly as specified in Table 502.3.

Exception: The percentage of gross roof assembly area that is permitted to be skylights shall be limited to 6%, when the following criteria are met:

1. The haze value of the skylight glazing material or diffuser for any of the layers or for the whole assembly shall be greater than 90% when tested according to ASTM D1003, without consideration of the scope of maximum haze. 2. All ambient lighting in daylit areas under skylights is controlled by multi- level daylighting controls that comply with Section 505.2.5, 3. The area weighted average U-factor and SHGC of the skylight does not exceed the values given in Table 502.4

Climate Zone 1 2 3 4 except 5 & 6 7 8 5 Marine 4 U-factor 1.35 0.95 0.90 0.90 0.90 0.90 0.90 0.60 SHGC 0.35 0.50 0.55 0.55 0.55 0.60 NR NR

Table 502.4 Alternate Requirements for Skylights with Daylighting Controls

3. Add new SECTION 505.2.5 (Check section number) as follows:

505.2.5 Automatic daylighting controls. When automatic daylighting controls are required by this code, the level of ambient lighting in the daylit areas shall be separately controlled by at least one multi-level daylighting control (sometimes referred to as “photo control”). The multi-level daylighting control shall reduce electric lighting in response to available daylight in steps or uniformly as described in Section 505.2.2.1 and shall automatically reduce ambient lighting power in the daylit area in direct proportion to the amount of lighting provided by daylighting to 50% of rated power or less. The multi-level daylighting control shall be located so that calibration and set point adjustment controls are readily accessible. The calibration adjustment controls shall also be located in such a manner as to not receive direct lighting from the skylights.

4. Add the following standards to Chapter 9:

ASTM Standard Reference Title Referenced in Number code section number D1003-00 Standard Test Method 502.5 for Haze and Luminous Transmittance of Transparent Plastics

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