TECHNICAL LIBRARY | SHADOW BOXES:
Shadow Boxes generally consist of clear glazing, a cavity behind the glazing and an insulated panel/tray.
SHADOW BOX Vs. SPANDREL PANEL
- Shadow Box should not be confused with a glazed spandrel panel.
- Key feature of shadow box is the air cavity behind external glazing.
- Commonly in spandrel panel application the insulation is butted up against the spandrel glass.
- A further difference is type of glazing used; shadow boxes generally use transparent glass, whereas glazed spandrels use opaque glass (painted, fritted, etc).
WHY USE A SHADOW BOX?
- Shadow boxes are used for the particular appearance they give. The cavity behind the glazing adds depths to the appearance, creating greater visual interest than can be achieved with a more typical glazed spandrel.
- Allows the use of the same glass as used in vision areas, giving visual continuity between different zones of the façade.
TO VENT OR NOT TO VENT?
Un-vented Shadow Box Pros/Cons:
- Pros- Increase minimum cavity temp, no structural ban pans required, minimizes condensation, prevents dirt from entering cavity, can be used with face sealed systems.
- Cons- Increases max cavity temp, cannot be used with laminated spandrel glass, cavity pressures exist, cavity must be dry when assembled, humidity slow to dissipate, cannot be used with porous stone.
Vented Shadow Box Pros/Cons:
- Pros- Reduce max cavity temps, clears condensation, relieves internal pressures quickly, vents excessive humidity, can be used with laminated glass and stone.
- Cons- Reduces min cavity temps, may require structural back pans, introduces dirt into cavity, cleaning impractical, allows exterior humidity and fumes into cavity, condensation likely within cavity, cannot be used with face sealed systems, water/dirt marks possible.
COST AND VE IDEAS?
$10-12 / SF approx. net added cost to furnish shadow boxes in lieu of typical spandrel glass
Value Engineer Options / ideas:
- Replacing the shadow box on upper floors and/or less visible areas with spandrel glass.
- Changing to a darker tint or reflective glass to reduce the variation between vision and spandrel.
- Accenting the spandrel area with reflective glass or metal panels
- These should be looked at on a case by case basis.