Glass Curtain WallsDesign, Engineering, and Performance

Building Enclosure Council ‐ Baltimore14 June 2016

John A. Jackson, M.Eng, AIASimpson, Gumpertz, & Heger

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Provider Number: J380Course Number: GLASSCW60

© 2016 Simpson Gumpertz & Heger Inc.

Copyright Materials

Curtain Walls

Curtain Walls

• Systems• Performances• Testing &

Construction

Curtain Walls

• Terminology• Stick-Built• Unitized• Glass Retention• Spandrel Panels• Transitions• Other Materials• Other Glazing Systems

• Systems• Performances• Testing &

Construction

Terminology

Mullion

Transom

Stack head

Stack sill

Stack joint

Spandrel panel

Stick-Built

Stick-Built

Stick-Built

Stick-Built

Stick Built

Unitized

Unitized

Unitized

Unitizedwet dry

“chicken head”

outside inside

thermal break

rainscreen gasket

movement at stack joint

Unitized

wet

dry

outside

inside

Unitized

Unitized

“chicken head” acts as lateral restraint for above panel

Anchor bracket

Embed anchor

Above panel

Unitized

Silicone boot

Unitized

“chicken head”

Panel splice

wetdry

1 panel

Capped(i.e. traditionally glazed)

Glass Retention

Structural Silicone Glazed(i.e. SSG)

Glass-to-Glass

Bolt-Fixing Clamped

Toggle-Fixing

Glass Retention

Spandrel Panels

Spandrel Panels

Spandrel Glass

Spandrel Panels

Shadow Box

Spandrel Panels

All Glass

Transitions

Perimeter sealant joint

Flexible membrane tied into glazing

pocket

Glazing stop installed on site

Transitions

Sealant

Aluminum plate

Panel hung from floor

above

Flexible membrane

glued to everything

Transitions

Other Glazing Systems

Punched Windows Ribbon Windows

Other Glazing Systems

Window WallStorefront

Other Glazing Systems

Glass FinsCables & Rods

Other Glazing Systems

Double Skins Free-Form

Other Materials

Metal Panel TerracottaStone

Curtain Walls

• Structural• Movement• Water-tightness• Airtightness• Solar Control• Thermal• Condensation Assessment• Ventilation• Acoustics• Fire• Blast• Access & Maintenance

• Systems• Performances• Testing &

Construction

Structural

Deflection due to wind suction

Deflection due to wind pressure

Framing Deflection

Internal steel reinforcement

StructuralGlass Deflection

Glass Center-Pane Deflection

Movement

• Live Load Deflections

• Wind Load Deflections/Sway

• Seismic Deflections/Sway

• Thermal Movements

• Moisture Movements

• Long-Term Shrinkage

• Differential Settlement

• Superimposed Dead Load Deflections

• Construction Sequencing

• Fabrication Tolerances

• Erection Tolerances

• Dead Load Deflections

• Snow/Rain Load Deflections

Movement

Movement

Δ

H

Water-tightness

Water-tightness:

Provide aluminum curtain wall systems that do not evidence water penetration when tested according to ASTM E331 (static) and AAMA 501.1 (dynamic) for one 15 min. cycle at a minimum differential static pressure of 20% of the peak positive wind load design pressure, but not less than 15 psf.

Barrier (i.e. no provision for drainage within system)

Drained and Ventilated(i.e. provision for drainage)

WATER DRAINAGE

Water-tightness

Water-tightness

Drainage at Base(i.e. pressure moderated)

Zone Dammed Drainage(i.e. pressure equalized)

Water-tightness

Continuous two lines of water defense within system and at transition to adjacent assemblies.

First Line

Second Line

Airtightness

Air Infiltration/Exfiltration:

Provide aluminum glazed curtain wall systems with maximum air leakage of 0.06-cfm/sq ft of fixed wall area when tested according to ASTM E283 at a minimum static-air-pressure differential of 6.24-lbf/sq ft.

Airtightness

Continuous air barrier within system and at transition to adjacent assemblies.

Air barrier

Solar Control

Solar Energy:

• Infrared (i.e. Heat Gain)

• Visible (i.e. Light Transmission)

• Ultraviolet (i.e. Material Degradation)

Solar Control

Laye

r 1

Laye

r 2

Solar Heat Gain Coefficient (SHGC)- Total percentage of solar heat energy transmitted through a material, including energy absorbed and reradiated - European designation: G-value = SHGC- Shading Coefficient (SC) is an antiquated term, based on a standardized glass thickness (SHGC = 0.87 * SC)- Unit-less Value, ranges from 0 to 1.0- Typical SHGC of glazing include:

High Performance, Low-E 0.25 – 0.55

1 2 3 4

Typical position of Low-E Coating

Solar Control

Solar Heat Gain Coefficient (SHGC)

Visible Light Transmission (VLT)

Light to Solar Gain (LSG)= VLT/SHGC

Thermal1)2)3)U-value of

Glazing System

Center of Glass U-value

Thermal

Frame

Edge(2-1/2”)

Edge(2-1/2”)

Center Pane

Center Pane

Thermal

Thermal Barrier

Continuous thermal barrier within system and at transition to adjacent assemblies.

Condensation Assessment

Interior dew point temperature: 37°F

Interior Temperature: 70°FInterior Relative Humidity: 30%

Exterior Temperature: 17.3°FExterior Wind Speed: 15.3 mph

Ventilation

Acoustics

• Inside to Outside • Vertical Flanking (floor-to-floor)• Horizontal Flanking (across partitions)

Fire

UL Tested Edge of Slab Firesafing Assembly

Blast

Peak Pressure

Initial pressure

Initial rebound

Impulse = area under curve

Approx. Impulse = area under triangle

Access & Maintenance

Conflicting Requirements

Thermal Control                            vs        TransparencyHigh cost Complexity                    vs       StandardisationLow visual Weight                         vs       StrengthNeed for Ventilation & Access    vs       WeathertightnessNeed for Ventilation & Access    vs       Acoustic controlHigh quality                                   vs        CostComplexity                                    vs        Fast installationNew technology                           vs        RiskArchitectural Forms                     vs        Maintenance Access

Delegated Design

Glazed aluminium curtain wall systems shall be designed, engineered, fabricated, and installed by a single-source curtain wall sub contractor:

• Structural Calculations• Air and Water Management• Thermal Calculations• Condensation Assessment• Edge of Slab Firesafeing

Curtain Walls

• Systems• Performances• Testing &

Construction

• Lab Mockup Testing• Fabrication• Storage• Transportation• Installation• Field Testing

Lab Mockup Testing

Air Infiltration/Exfiltration (ASTM E283) Static Water (ASTM E331)

Lab Mockup Testing

Dynamic Water (AAMA 501.1)

Lab Mockup Testing

Deflection (ASTM E330) Thermal Cycling/Condensation Assessment (AAMA 501.5)

Lab Mockup Testing

Horizontal Movement (AAMA 501.4) Vertical Movement (AAMA 501.7)

Fabrication

Fabrication

Storage

Transportation

Installation

Installation

Installation

Site applied panel splice

Field Testing

Hose Testing (AAMA 501.2) Chamber Air (ASTM E783)Chamber Water (ASTM E1105)

Questions?

John A. Jackson, M.Eng, AIASimpson, Gumpertz, & Heger