In this article, readers will learn about the history and evolution of Pilkington and the glass industry, the invention and technical details of insulated glass, and its development and manufacturing process. Also included are the market response, adoption, and impact of insulated glass on the glass industry and environment, as well as advancements and innovations since the 1950s. Discover how the introduction of insulated glass led to increased energy efficiency, environmental benefits, and customization options for specialized applications.

The Development of Insulated Glass by Pilkington in the 1950s


Table of Contents

Background of Pilkington and Glass Industry

Pilkington’s History and Origins

Pilkington is a multinational glass manufacturing company based in the United Kingdom. It was founded in 1826 by John William Pilkington and his brother-in-law, William Hargreaves, in St Helens, Lancashire. Initially, the company was a partnership, specializing in the production of crown window glass. By the 1850s, Pilkington had become one of the largest glass producers in Britain.

In the late 19th century, Pilkington developed the “Wired Glass” technique, which involved embedding a wire mesh between two layers of glass. This innovation became widely popular as it provided a stronger and more fire-resistant glass, particularly in public buildings.

In 1920, Sir Alastair Pilkington, a descendant of the founders, began working for the company. He was a pivotal figure in the history of Pilkington and the glass industry, having led significant technological advancements, including the development of the Float Glass Process in the 1950s.

Today, Pilkington is a subsidiary of the Nippon Sheet Glass Co. Ltd., a Japanese glass company, after they acquired Pilkington in 2006. The company continues to be a major player in the global glass industry, focusing on the development and production of high-quality glass products for various sectors, including construction, automotive, and renewable energy industries.

Evolution of Glassmaking Techniques

Throughout history, glassmaking techniques have evolved to meet the demands for higher quality and more versatile glass products. In ancient times, glass was made by heating silica sand and other natural materials, and then molding or blowing the molten glass. As time progressed, new techniques emerged.

There were several breakthroughs in glassmaking in the early 20th century. For example, the introduction of the “Flat Drawn Sheet” process allowed the production of large, thin, and grainless glass sheets. This process was an improvement over the traditional cylinder process, which was limited by the length of the glass cylinder that could be drawn.

However, the most significant advancement in the glass industry came in the mid-20th century with Sir Alastair Pilkington’s invention of the Float Glass Process. This revolutionary method changed the way flat glass was produced, making it easier and more economical to manufacture large, high-quality sheets of glass. The technique involved floating the molten glass on a bath of molten tin, producing a flat and smooth surface on both sides. This innovation completely transformed the glass industry and is still the standard process for flat glass production today.

Challenges in the Glass Industry in the 1940s and Early 1950s

The 1940s and early 1950s posed numerous challenges for the glass industry, particularly due to the effects of World War II and the rising demand for quality glass products in construction, automotive, and other sectors.

One major challenge during this time was the limited availability of raw materials, such as silica sand, soda ash, and limestone, which were vital for glass production. Economic constraints and transportation issues arising from the war led to higher costs, making the manufacturing of glass more expensive.

Another challenge faced by the glass industry was the pressure to produce higher quality glass products that met evolving architectural and automotive standards. The post-war period saw rapid growth in construction and urbanization, increasing the demand for large, high-quality glass sheets for commercial and residential buildings. Demand for automotive glass also grew, as the automobile industry expanded.

Lastly, the increasing competition within the glass industry led to significant research and development efforts to improve glass production techniques. Companies were racing to develop new, cost-effective, and efficient manufacturing processes that could produce large and high-quality glass sheets. This competitive environment set the stage for the introduction of the Float Glass Process, which addressed these market demands and propelled the glass industry into a new era of innovation and growth.

Driving Factors for Developing Insulated Glass

Insulated glass (IG) was developed as a solution to several building and architectural challenges that become apparent in the early 20th century. These challenges included the increasing need for energy efficiency, noise reduction, and effective climate control in buildings. With rapid urbanization and industrialization, buildings were being constructed with larger windows to allow for more natural light and improve aesthetics. However, larger windows also led to increased heat loss in colder months and heat gains during hot weather, leading to higher energy consumption for heating and cooling systems.

Another factor that accelerated the development of insulated glass was the need for better acoustical insulation. Urban environments were becoming noisier due to increased traffic and industrial activity, and soundproofing became a major concern for building occupants. Traditional single-pane glass was incapable of mitigating these noise issues, resulting in the need for innovative solutions like insulated glass.

The increasing focus on developing sustainable building materials and techniques to reduce the environmental impact of construction and operation also played a vital role in the invention and popularization of insulated glass, as it directly addressed energy consumption issues associated with large glazed areas.

Initial Concepts of Insulated Glass

Insulated glass units consist of two or more glass panes separated by an air or gas-filled space to reduce heat transfer. The concept dates back as early as the 19th century, with some early examples of IG-like structures found in the Alaskan and Canadian region where windows sometimes had additional panes added for insulation. However, these early examples did not feature the hermetically sealed units that characterize modern insulated glass.

The patent for a more refined version of insulated glass was filed in the United States by Carl A. Petersen in 1911. This patent described a double pane window setup where the two glass panes were separated by a compressed air gap, reducing the heat transfer between the indoors and outdoors. Though this design was more advanced than its predecessors, it still did not have the gas-tight seals or other features that have become standard for contemporary insulated glass units.

Another early attempt at insulated glass design was patented by Cleve Hammond in 1927, who proposed the use of airtight rubber gaskets to keep the two panes of glass separate. However, Hammond’s design still lacked many important features found in modern-day insulated glass, such as desiccants to absorb moisture within the sealed space or a spacer bar system.

Key Inventors and Innovators from Pilkington

The insulated glass industry saw a major breakthrough in 1952 when Sir Alastair Pilkington, a British engineer working for Pilkington Brothers Limited (now NSG Group), developed a revolutionary glass manufacturing process called the float glass method. This process produces high-quality, uniform glass sheets, enabling the production of insulated glass units with superior clarity, strength, and insulation properties.

Furthermore, in a 1965 patent, Pilkington engineer Harry J. Leigh introduced the concept of filling the space between the glass panes with a less conductive gas, such as argon, which further reduced the heat transfer through the unit and improved the overall efficiency of the insulated glass. This gas filling technique is now a common feature in the production of modern insulated glass units.

Another key development in insulated glass technology was the advancement in spacer bars, which are used to maintain the gap between the glass panes. Early spacer bars were made from metal, which conducted heat and limited the insulating properties of the glass unit. Over time, these metal spacer bars were replaced by warm-edge spacer bars made from materials with low thermal conductivity, leading to more energy-efficient insulated glass products.

Pilkington has played a pivotal role in shaping the modern insulated glass industry through various technological improvements, resulting in the widespread adoption of insulated glass in residential, commercial, and industrial construction. These advances have not only made buildings more energy-efficient and comfortable but also contributed to the overall push towards sustainable design and construction methods.

Technical Details and Composition of Insulated Glass Units

Components and Structure of Insulated Glass

Insulated Glass Units (IGUs) are made of multiple glass panes separated by an insulating space, usually filled with an inert gas. These layers and gas work together to provide energy efficiency by reducing heat transfer through the glass. The primary components of an IGU include the glass panes, which can be laminated, tempered or coated, the gas filling, spacer bars, and sealants. Here’s an overview of these components:

  1. Glass panes: These can be of different types, such as clear, laminated, toughened, or coated, depending on the desired properties. Clear glass is the most commonly used, but other specialized options can provide additional benefits, such as noise reduction, enhanced security, and solar protection.
  2. Gas filling: The space between the glass panes is filled with an inert gas (argon, krypton, or xenon) or simply air to minimize heat transfer. The choice of gas depends on factors such as performance requirements, cost, and availability.
  3. Spacer bars: These separate the panes and create the insulating space. They are usually made of aluminum or another metal, sometimes with a thermal break for improved insulation. The bars also contain desiccants to absorb any moisture that may have entered the space between the glass levels.
  4. Sealants: Polyisobutylene and silicone are the most commonly used materials to provide a air-tight barrier around the edges of the IGU. This prevents moisture from entering the unit and maintains the insulating properties of the gas inside.

Types of Gas Fillings and their Properties

Gas fillings play a crucial role in IGUs, reducing heat transfer and providing better insulation. The most common types of gases used include:

  1. Argon: It’s an inexpensive, inert, and non-toxic gas that offers superior insulation compared to air. It reduces heat transfer by minimizing convection currents between the glass panes.
  2. Krypton: More effective than argon, but also more expensive and less readily available. It has better insulating properties than argon due to its lower thermal conductivity.
  3. Xenon: Although it provides excellent insulation, it is the most expensive and least available option. Typically reserved for specialized applications where high-performance insulation is required.

Sealants and Spacer Bars

Sealants and spacer bars play a vital role in maintaining the structural integrity, insulation, and durability of the IGU.

  1. Sealants: IGUs rely on a double seal system, generally comprised of a primary sealant (polyisobutylene) to prevent moisture ingress, and a secondary sealant (silicone) to provide structural bonding between the glass panes and spacer bars.
  2. Spacer bars: Spacer bars are responsible for maintaining the uniform gap between glass panes and used to accommodate a desiccant to absorb any moisture. Metal spacer bars are most common, but other materials such as plastic, foam, or hybrid types are available, offering better thermal insulation.

Advantages of Insulated Glass

IGUs provide several key benefits:

  1. Energy efficiency: By reducing heat transfer, IGUs significantly lower energy consumption for heating and cooling, reducing energy bills and carbon emissions.
  2. Noise reduction: Multiple glass panes and gas fillings can help to dampen exterior noise.
  3. Condensation control: Moisture between the glass panes is minimized thanks to the gas fillings, sealants, and desiccants, reducing the likelihood of mold and rot.
  4. UV protection: Coated glass can block harmful ultraviolet rays, providing protection for interior furnishings and artwork.

Development and Manufacturing Process

Research and Development

R&D plays a key role in the evolution of IGUs. Innovations in glass technology, such as low-emissivity coatings, help to enhance insulation properties. Additionally, the development of gas fillings with better thermal performance and improvements in sealant materials contribute to ongoing advancements in insulated glass production.

Challenges and Breakthroughs in Manufacturing

The manufacturing process of IGUs has seen significant advancements, resulting in improved efficiency and performance. Challenges in IGU production include maintaining airtight seals, ensuring accurate and consistent gas filling, and handling larger glass panes. Breakthroughs in automated processes, quality control, and gas filling technologies have led to improvements in the quality and reliability of the final product.

Improvements in Production Efficiency

Advancements in automation and equipment for glass cutting, spacer bar assembly, and gas-filling operations have resulted in increased efficiency and reduced production times. These improvements contribute to cost reduction and allow for more competitive pricing in the IGU market.

Quality Control and Standards

Strict quality control measures are crucial to ensure the performance and durability of IGUs. Manufacturers must adhere to industry-specific standards and certifications, such as ASTM, IGCC, and EN standards. These benchmarks guarantee that the final product is safe, energy-efficient, and reliable. Regular inspections, tests, and audits ensure adherence to these standards, resulting in higher customer satisfaction and a reduction in warranty issues.

Market Response and Adoption of Insulated Glass

Initial Market Reception and Adoption

Insulated glass, also known as double-glazed glass, is a revolutionary product that involves two or more glass panes separated by a vacuum or gas-filled space. This design significantly boosts the glass’s insulation capabilities and thermal efficiency. When it was first introduced, the market response to insulated glass was overwhelmingly positive as it brought a plethora of benefits to the construction, energy, and HVAC industries. The improved insulation provided by insulated glass translates to significant energy savings and reduced heating and cooling costs.

The growing concerns surrounding energy efficiency and the reduction of carbon emissions also played a significant role in the initial market reception of insulated glass. Environmental awareness has been on the rise over the past few decades, leading to an increased demand for green building materials and energy-efficient products. Insulated glass perfectly fits this niche, contributing to its rapid integration into the construction industry. This adoption was bolstered by various regulatory changes and policies that encouraged energy-efficient construction and the use of insulated glass to meet the requisite standards.

As a result of these factors, early adopters of insulated glass included pioneering architects, building contractors, and developers who were either driven by environmental concerns or looking to enhance their projects’ energy efficiency. Many of these initial adopters saw incredible benefits to using insulated glass, not only in terms of energy savings but also in the enhancement of occupant comfort and overall building performance.

Key Industries and Applications

Insulated glass has been widely utilized across various industries and applications, benefiting from its unique insulation and energy efficiency properties. Some prominent industries and applications that have capitalized on the adoption of insulated glass include:

  1. Construction: Insulated glass has become a staple component for both residential and commercial construction projects. It offers improved thermal insulation, reduces condensation, and brings about substantial energy savings and green building advantages.
  2. Transportation: Insulated glass is used in the automotive and aerospace industries to provide enhanced insulation and reduced noise penetration, resulting in a comfortable and energy-efficient cabin environment for passengers and drivers.
  3. Refrigeration: Commercial refrigeration units and appliances, such as display cases and walk-in coolers, now frequently incorporate insulated glass for optimal temperature control and energy efficiency.
  4. Medical facilities: Clean rooms, laboratories, and other controlled environments in medical facilities greatly benefit from incorporating insulated glass due to its ability to maintain stable and consistent temperatures.
  5. Greenhouses: Insulated glass enables greenhouse owners to provide optimal growing conditions while minimizing energy consumption and ensuring the controlled environment’s stability.

Global Expansion and Market Penetration

As the benefits of insulated glass became more widely recognized and appreciated, its adoption quickly expanded across the globe. From Europe to North America, Asia, and beyond, the market penetration of insulated glass has been nothing short of exceptional. This worldwide expansion was facilitated by multiple factors, including growing awareness of energy efficiency and climate change, governmental policies and incentives, and advances in glass technology.

To meet the demand for insulated glass, manufacturers have also scaled up their production capacities and introduced advanced solutions such as triple glazing, gas-filled variants, and high-performing low-e coatings. The rapid rise of smart glass technology has further bolstered insulated glass adoption, offering dynamic, adaptive insulation properties aligned with occupants’ specific needs in a space.

Presently, the global insulated glass market continues to grow and is expected to witness noteworthy expansion over the coming years. This can be attributed to the evolving market landscape that prioritizes energy efficiency, sustainability, and occupant comfort – factors that encapsulate the core benefits of insulated glass. With keen market interest and ongoing innovation, the future of insulated glass remains incredibly promising.

Impact on the Glass Industry and Environment

The insulated glass manufacturing sector has made significant strides in recent years, implementing environmentally conscious and energy-efficient practices with the primary aim of reducing their carbon footprint. The glass industry has witnessed a shift in production methods and designs to incorporate sustainable practices while prioritizing energy conservation. This article will discuss the changes in the glass industry’s practices, the resulting improvements in energy efficiency and conservation, and the environmental benefits of insulated glass.

Changes in Glass Industry Practices

Historically, the glass industry’s production processes were energy-intensive and highly reliant on nonrenewable resources. This resulted in a negative environmental impact, contributing to air pollution, greenhouse gas emissions, and resource consumption. However, the industry’s practices have evolved over time, with companies placing a strong emphasis on eco-friendly technologies and production processes.

A significant change in the manufacturing process is the substitution of traditional raw materials with recycled glass, known as cullet. The utilization of cullet reduces energy consumption, lowers production costs, and minimizes the need for natural resources. Moreover, recycling reduces waste, as discarded glass products are employed as reusable materials in the production process, thus diminishing the demand for landfill space.

Another notable change in industrial practices involves the development and use of advanced glass technologies, such as low-emissivity glass (Low-E) and insulated glazing units (IGUs). These innovations mainly focus on improving energy performance and reducing heat loss, thereby contributing to lower energy consumption in residential and commercial buildings.

Energy Efficiency and Conservation

As a result of the changes in glass industry practices, significant progress has been made in the realm of energy efficiency and conservation. The use of insulated glass, in particular, has led to significant energy savings and thermal comfort improvements in buildings’ interiors.

Insulated glass, which consists of two or more layers of glass separated by a spacer and an insulating gas, reduces heat transfer through windows. Updated manufacturing technologies, like the use of warm-edge spacers or gas-filling techniques, have further improved the energy efficiency of insulated glass. These advancements have allowed for better performance throughout the different seasons, where the insulated glass helps maintain a consistent temperature indoors, regardless of external conditions.

Low-E coatings, an innovation often employed in insulated glass, have also contributed immensely to energy efficiency. These coatings, made of thin metallic layers, minimize heat transfer by reflecting long-wave infrared energy back into the interior spaces during colder months and blocking solar heat in the summer.

Environmental Benefits of Insulated Glass

The widespread adoption of insulated glass has resulted in numerous environmental benefits, including reduced reliance on fossil fuels due to improved energy efficiency. With a decrease in energy consumption, there is a subsequent reduction in greenhouse gas emissions from power plants, contributing to a smaller carbon footprint for both the glass industry and individual buildings.

Moreover, the recycling of glass waste in manufacturing processes has diminished the need for virgin raw materials, which in turn conserves finite resources and preserves natural habitats. This practice also minimizes landfill use, thereby reducing the risks associated with land pollution and groundwater contamination.

Lastly, insulated glass can significantly reduce noise pollution in urban areas. The airtight seal created by the spacer and the use of multiple glass layers can block external noise, offering sound insulation and improving the quality of life for residents.

In summary, the changes in the glass industry, driven by technological advancements and sustainability goals, have resulted in energy-efficient and eco-friendly products that contribute to a healthier environment. Insulated glass, in particular, has transformed the way we manage temperature and energy usage in buildings, while minimizing harmful emissions and improving living conditions.

Advancements and Innovations Since the 1950s

The development of insulated glass has come a long way since its inception in the 1950s. Innovations in glass technology have allowed for improvements in energy efficiency, durability, and adaptability. This article will discuss some of the advancements and innovations in insulated glass over the past several decades, focusing on the development of low-emissivity coatings, smart glass technologies, customization and specialized applications, and current and future trends in the industry.

Development of Low-Emissivity Coatings

Low-emissivity (low-E) coatings are microscopically thin metallic coatings applied to the surface of glass, allowing it to transmit visible light while reflecting heat from the sun. This technology helps minimize the amount of ultraviolet and infrared radiation passing through the glass without compromising its clarity. UK’s Pilkington Brothers invented low-emissivity coatings in 1973, revolutionizing the insulated glass industry.

Throughout the years, low-E coatings have improved in both performance and durability. Initially, the coatings were sensitive to moisture, limiting their application to the inner surfaces of insulated glass units. Over time, advancements in the development of sputter coatings, using ion-assisted deposition, produced more durable coatings that can be applied to the outer surfaces of the glass.

There are now different types of low-E coatings, including hard-coat and soft-coat. Hard-coat low-E coatings are applied during the process of making float glass through a pyrolytic process, making them more durable. Soft-coat low-E coatings require a vacuum sputtering process, resulting in a slightly better thermal performance but with more delicate surfaces.

Smart Glass Technologies

In addition to low-E coatings, smart glass technologies have emerged as a significant innovation in insulated glass. One such technology is electrochromic glass, which uses a small voltage to change the tint of the glass, allowing it to transition between clear and opaque states. This type of glass can help regulate the amount of light, glare, and heat entering a building, improving its energy efficiency.

Another smart glass technology is thermochromic glass, which changes its transparency in response to temperature changes. This type of glass can help regulate temperature inside a building without the need for curtains, shades, or blinds.

Lastly, suspended particle devices (SPDs) contain microscopic particles that become transparent when an electric current is applied, allowing for rapid control of light and glare transmission. This technology has potential applications in various industries, including automotive, aerospace, and commercial building industries.

Customization and Specialized Applications

Advancements in manufacturing processes and materials have also enabled increased customization and specialization of insulated glass, which has allowed for the development of products tailored to specific applications and industries. For example, the development of curved insulated glass has provided architects and designers with additional flexibility to design unique and visually appealing structures.

Additionally, laminated and tempered glass can now be incorporated into insulated glass units (IGUs) to improve safety, security, and acoustics in relevant applications. This has resulted in the use of insulated glass in various settings, including transportation hubs, schools, and high-security areas.

Bullet-resistant glass, hurricane-resistant glass, and fire-resistant glass have also been developed to meet the specific needs and requirements of various applications and environments. The ongoing advancements in the insulated glass industry continue to offer new and innovative solutions to meet the ever-changing demands of modern construction and design.

Current and Future Trends in Insulated Glass

The future of the insulated glass industry is likely to continue trending toward increased energy efficiency and sustainability, the use of smart glass and advanced coatings technologies, and further customization to meet the demands of modern design and construction.

Emerging trends in the industry include the integration of photovoltaic cells into IGUs to harness solar energy, advances in vacuum insulated glazing (VIG) for improved energy efficiency, and the development of glass that incorporates nanotechnologies to enhance performance and properties.

As the global focus on sustainability and energy efficiency grows, the insulated glass industry will continue to evolve and innovate to meet the needs of architects, builders, and property owners. With the ongoing advancements and innovations in the field, the future of insulated glass appears bright and full of potential.

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FAQs on The Development of Insulated Glass by Pilkington in the 1950s

What is insulated glass and how was it developed by Pilkington in the 1950s?

Insulated glass, also known as double-glazed glass, consists of two or more glass window panes separated by a vacuum or gas-filled space to reduce heat transfer. Invented by Sir Alastair Pilkington, float glass technology revolutionized glass production, making low-cost, high-quality insulated glass possible in the 1950s.

What motivated Pilkington to invent insulated or double-glazed glass?

The motivation for Pilkington’s invention stemmed from the need to improve the energy efficiency of buildings, limiting heat loss through windows. Consequently, double glazing was developed, providing better insulation, reduced condensation, and lower energy costs.

What is the role of the vacuum or gas-filled space in insulated glass?

The vacuum or gas-filled space in insulated glass serves as an insulating barrier that minimizes the rate of heat transfer. This leads to improved thermal performance in windows, reducing energy costs and enhancing comfort within a building.

What is the importance of the float glass technology patented by Pilkington?

Float glass technology invented by Pilkington transformed the glass industry, allowing the production of large, high-quality, uniform glass sheets. This development led to an increase in the availability of insulated glass for windows, improving energy efficiency in buildings worldwide.

What materials did Pilkington use to make insulated glass?

Pilkington initially used silica, soda, and lime to produce float glass, which was then made into insulated glass using an inert gas or vacuum sealed between two panes. The inert gas, like argon or krypton, plays a crucial role in improving the insulating properties of glass.

What was the impact of Pilkington’s insulated glass on the construction industry?

Pilkington’s insulated glass brought about significant change in the construction industry, offering improved energy efficiency and lower energy costs. Architects and developers have since adopted the technology more broadly, leading to better-designed and sustainable buildings.


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