Spatial Materiality: Glass Fundamentals and Architectural Use and History

Glass Fundamentals in the Built Environment

• Context: Why Glass Matters

  • Glass is a material of paradoxes: it is simultaneously simple and complex; it is transparent and reflective, yet fragile but strong.
  • Ludwig Mies van der Rohe (Architect) Quote: "Glass is the most honest material — it doesn't disguise what it is."
  • Disciplinary Applications:
    • Architecture: Used for facades, skylights, and curtain walls to invite light and foster visual connections to the exterior.
    • Interior Design: Used for partitions, doors, and furniture to create openness while maintaining light flow and functional separation.
    • Landscape Architecture: Used in pavilions, water features, and greenhouses to mediate light and transparency in outdoor settings.

• Experience: Impact on Spatial Perception

  • Philip Johnson (Designer) Quote: "The great thing about glass is that it's everywhere and yet disappears at the right moment."
  • Jean Nouvel (Architect) Quote: "Glass is a material of light and transparency — it allows space to breathe."
  • Key Functions of Spatial Experience:
    • Connection and Separation: It can divide a room physically while keeping it visually united.
    • Light Manipulation: It enhances or diffuses light to shape mood.
    • Visual Illusion: It reflects surroundings to double the visual experience or create architectural illusions.

• Sensation: Impact on Sensory Perception

  • Sight (Visual):
    • Transparency connects spaces (e.g., floor-to-ceiling windows).
    • Reflection creates depth and light play (e.g., mirrored facades).
    • Tint and color affect psychological mood (e.g., dichroic glass panels).
  • Touch (Tactile):
    • Smooth, cool surfaces provide a material contrast to masonry or wood.
    • Textured or laminated glass invites tactile awareness (e.g., glass floors).
  • Sound (Acoustic):
    • Glass can reflect sound or, when double-glazed, dampen it to create privacy.
  • Temperature (Comfort):
    • Sunlight through glass provides warmth (passive heating).
    • Surfaces are generally cool to the touch.
  • Psychological/Emotional:
    • Connects inhabitants to nature and guides movement through transparency.

Materiality and Chemistry of Glass

• The Science of Amorphous Solids

  • Glass is classified as an Amorphous Solid, meaning its atoms or molecules are not arranged in a regular, repeating crystalline pattern.
  • It has the structure of a "quickly cooled liquid" that did not have time to form crystals, which accounts for its transparency and brittleness.

• Glass Composition Types

  • Soda-Lime-Silica Glass (Common Window Glass):
    • Silica ($SiO_2$): $74\%$ (The main glass former, providing hardness and chemical durability).
    • Soda ($Na_2O$): $15\%$ (Acts as a flux to lower the melting temperature).
    • Lime ($CaO$): $10\%$ (A stabilizer that makes glass chemically durable and less water-soluble).
    • Alumina ($Al_2O_3$): $1\%$ (Improves durability and prevents devitrification/crystallization).
    • Properties: Inexpensive, chemically stable, and recyclable.
  • Lead-Alkali-Silica Glass (Crystal):
    • Contains $18-40\%$ Lead Oxide ($PbO$).
    • Properties: High refractive index (brilliant sparkle), high density, lower melting point, and high electrical resistance.
  • Borosilicate Glass (e.g., Pyrex):
    • Includes Boron Trioxide.
    • Properties: Highly resistant to thermal shock and chemical corrosion; can withstand sudden temperature changes.

• Core Material Properties

  • Transparency: Typically allows $86-89\%$ light transmission.
  • Thermal Transfer: Heat is transferred via conduction, convection, and radiation.
  • Chemical Resistance: Resistant to most chemicals except hydrofluoric acids.
  • Porousness: Non-porous.
  • Recyclability: Fully recyclable, though typically has high embodied energy in initial production.

Glass Treatments and Strengthening

• Annealed Glass:

  • Standard glass cooled slowly to relieve internal stresses.
  • Safety: Low (breaks into large, dangerous shards).
  • Use: Picture frames, jars, general glazing where safety is not critical.

• Tempered (Toughened) Glass:

  • Process: Heated to $600-720^{\circ}C$ and rapidly cooled with high-pressure air.
  • Properties: $3$ to $5$ times stronger than annealed glass.
  • Safety: Breaks into small, blunt pieces.
  • Use: Shower screens, car side windows, glass doors, and tabletops.

• Laminated Glass:

  • Process: Two or more glass layers sandwiched with a plastic interlayer, usually Polyvinyl Butyral (PVB) or SentryGlas Plus (SGP).
  • Safety: Holds together when broken; provides security and UV filtering.
  • Use: Car windshields, skylights, and safety glazing.

• Insulated Glass Units (IGU):

  • Double or triple-glazed systems separated by an air or gas layer (like Argon).
  • Reduces heat transfer and improves acoustic performance.

Mechanisms: The Science of Energy Transfer

• Energy Terminology:
  • Transmission: The amount of radiation passing through the glass.
  • Reflection: The amount of radiation bouncing off the surface.
  • Radiation: The emission or absorption of thermal energy (heat).
  • Solar Heat Gain: The quantity of solar energy entering a space through the glazing.
• Climate Response:
  • Clear glass is ideal for passive heating in cold climates.
  • Reflective glass is more effective in warm climates to reduce cooling demands.

History and Evolution of Glass

• Chronology:

  • $2600\,BC$: Early evidence in Mesopotamia (byproduct of metalworking).
  • Mid-$2000s\,BC$: Glass beads in Egypt.
  • $1st\,Century\,BC$: Syrian glassmakers in Hama and Aleppo invent glassblowing.
  • $79\,AD$: Evidence of glass window sheets in Pompeii.
  • $15th\,Century\,AD$: Angelo Barovier (Venice) invents transparent glass.
  • $1952-1959$: Sir Alastair Pilkington develops the Float Glass Process, floating molten glass on molten tin. This cost $28$ million pounds (approx. $150$ million today) to develop.

• Legacy Techniques:

  • Mirrors: Originally Roman glass backed with lead or tin to improve reflectivity.
  • Crown Glass: Created by spinning molten glass into a disk; characterized by a central "bullseye" pattern.
  • Coloration: Metal oxides added during melting — Copper for red, Cobalt for blue, Gold for rich reds/purples.

Glass Failure and Performance Issues

• Causes of Failure:

  • Mechanical: Impact from objects (hail, rocks), wind loads, or poor installation (lack of tolerance in framing).
  • Thermal: Expansion due to heat; failure of sealants.
  • Internal: Impurities like Nickel Sulphate or air bubbles.

• Case Studies in Failure:

  • John Hancock Tower, Boston ($1973$): Designed by I.M. Pei & Partners. Known as the "Plywood Palace" because windows were constantly falling out and had to be replaced with temporary plywood panels.
  • Waterfront Place, Brisbane ($1990$): Experienced approximately $140$ spontaneous glass failures between $1990$ and $1997$.

Sustainability and Design Responsibility

• Design Ethics: Glass is not inherently sustainable; design decisions make it so.
• Sustainability Potential:
  • True closed-loop recycling.
  • Daylighting reduces artificial lighting needs.
  • Lightweight nature saves on transport compared to masonry.
• The Reality of Non-Sustainability:
  • High embodied energy due to extreme manufacturing temperatures.
  • Poor thermal performance if over-glazed or untreated.
  • Short replacement cycles for seals and coatings.
• Design Recommendations:
  • Use less glass, but use it better.
  • Prioritize performance (Low-E coating, shading).
  • Design for the specific orientation of the sun.
  • Detail for disassembly and reuse.

Architectural Case Studies

• Crystal Palace, London ($1851$): Joseph Paxton. A modular iron-and-glass structure ($1,848$ feet long). It demonstrated glass as an industrialized enclosure but suffered from severe overheating.
• Farnsworth House, Illinois ($1951$): Mies van der Rohe. A minimalist glass pavilion expressing spatial ideology through total transparency.
• The Glass House, Connecticut ($1949$): Philip Johnson. A single-story minimalist home that blurs the line between inside and the landscape.
• Walkie Talkie Building, London ($2014$): Rafael Violy. The concave glass facade acted as a "death ray," reflecting and focusing sunlight to melt cars and create intense street-level heat.
• Apple Park, California ($2017$): Foster + Partners. Features the world’s largest curved glass panels to create a seamless "spaceship" design.
• Under Restaurant, Norway ($2019$): Snohetta. Uses thick, pressure-resistant structural glass to create an underwater dining experience.
• AEAJ Green Terrace, Japan ($2023$): Kengo Kuma. Uses glass as an "invisible skin" to protect a sensory interior of timber and plants.

Questions & Discussion

• Campus Glass Hunt Reflection:

  • How does the glass change the way light moves through the space?
  • What emotions does the space evoke (open, private, connected)?
  • How would the experience change without the glass?
  • Where is glass used for function versus decoration, and where do those roles blur?

• Assessment 1: Material Passport (Report):

  • Sourcing Samples: Students should be polite and honest with suppliers ("I am a student"). Resources include Simple Sample (Australia) and commercial supplier directories.
  • Photography Requirements: Use high-quality light (natural or directional lamp), clean setup (white paper/foam core backdrop), and careful framing. No professional equipment is needed; a phone camera is sufficient.