Checks the three prescriptive fenestration requirements in one place: maximum glazing area with the daylight-controls increase pathways (C402.4.1), the minimum-skylight mandate for large high-bay spaces with the Equation 4-4 effective aperture (C402.4.2), and the maximum U-factor / SHGC table lookup with projection factor and increased allowances (C402.4.3).
Vertical fenestration ≤ 30% of gross above-grade wall area; skylights ≤ 3% of gross roof area. Climate Zones 1–6 may reach 40% / 6% with daylight zones and responsive controls. C402.4.1
Large high-bay spaces in listed occupancies must place toplit zones over ≥ half the floor area and meet a 3%-skylight ratio or a ≥ 1% effective aperture, unless an exception applies. Triggered spaces also require toplit-zone lighting controls (C402.4.2.1) and, for certain uses, diffusing skylights (C402.4.2.2). C402.4.2
Required maxima from Table C402.4 by climate zone, fenestration category, orientation, and projection factor. C402.4.3
Where products differ in PF or category, evaluate each separately. Area-weighted U-factor (C402.4.3.4): you may meet the U-factor limit with an area-weighted average within a single fenestration category (e.g. several windows of differing U combined into one value), but products from different categories — fixed, operable, entrance, skylight — cannot be combined. Enter the area-weighted U above.