Exterior sunshades and louvers — the shading half of the energy-code equation.

Solar heat gain coefficient (SHGC) describes how much of the sun's heat a glazing assembly lets through. Every commercial glass package gets specified to a U-factor and SHGC target under the project's energy code path. Florida's 8th Edition (2023) Energy Code sets maximum U-factor and SHGC values for commercial fenestration in Table C402.4, and requires replacement fenestration on existing buildings to meet those same limits when units are swapped out — not the code in force when the building was built. That's a glass-package decision.

Exterior shading is the other half of the same problem, attacking it before the sun ever reaches the glass surface. A sunshade, louver blade, or fin mounted outboard of the glazing plane intercepts direct solar radiation at the building skin instead of asking the glass to reject it after it's already inside the assembly. The two strategies aren't interchangeable — a high-SHGC glass package with well-designed shading can outperform a low-SHGC package with none, especially on south- and west-facing elevations carrying the most direct sun. The same code cycle that tightened glazing SHGC and U-factor limits also added an overhang projection-factor requirement tied to fenestration orientation — a direct, code-referenced link between shading geometry and glazing compliance, not just an aesthetic add-on.

The controlling numbers — exact SHGC target, exact projection factor, exact orientation cutoffs — are always project-specific, tied to the building's climate zone and the energy model the design team ran. This page is the installer's-eye view of how the hardware gets designed and attached; the energy compliance path itself belongs in the project's energy-code compliance documentation.

A sunshade drawing usually shows up on the architectural elevation and the structural steel package. What it doesn't always resolve cleanly is the connection back into the storefront or curtain wall frame that's carrying the glazing load at the same location. That's the point where this becomes a glazing-installer's problem, not just a metals subcontractor's:

• Load path back to the mullion. Cantilevered sunshades impose bending and wind loads on the curtain wall mullion or storefront header they attach to — loads the base glazing system wasn't necessarily sized for until the sunshade was added to the design. Confirm mullion capacity includes the shading device's imposed load, not just the glass and wind pressure on the vision area.
• Penetrations through the weather barrier. Every bracket that ties a sunshade back to the structure or the curtain wall frame is a potential water path. Bracket penetrations need to be detailed and flashed at the same rigor as any other envelope penetration — sealant alone at a structural bracket is not a detail, it's a callback waiting to happen.
• Thermal bridging at the attachment. A shading device is doing energy-code work, but a poorly isolated bracket can undercut it by creating a thermal bridge straight through the insulated frame. Thermally broken brackets or standoff isolation matter more on a shading connection than people expect.
• Differential movement. The curtain wall frame moves with thermal cycling and building deflection; a stiff shading structure bolted rigidly to it without accounting for that movement will eventually telegraph stress back into the glazing anchorage.
• Coordination sequencing. On new construction, sunshade brackets are easiest to set before the glazing goes in. On a retrofit or recladding scope, retrofitting shading onto an existing storefront or curtain wall means working around glass that's already in place — a different sequencing and access problem entirely.