A window—seemingly a simple structure—has been a companion to humanity for centuries, evolving in tandem with the progress of civilization. Today, it serves not only as a source of light but also as a crucial element of insulation, privacy, and even technological innovation in smart homes. What did the earliest windows look like? Which key moments shaped their current form? Let’s explore the history of windows, filled with surprises and intriguing facts.
Ancient Times: Windows as Wall Openings
The first “windows” were nothing more than openings in thick walls, designed to allow ventilation and light. In Egypt and Mesopotamia, the cradles of civilization, wall openings were protected from dust and intense sun using wooden screens, cloth, or animal hides. Interestingly, Egyptians hung damp mats in these openings to cool the air as it passed through, a primitive precursor to air conditioning.
In ancient Rome, the first glass windows appeared, although they were limited to the wealthy and were extremely fragile. The Romans developed glass-blowing techniques, creating small panes set into lead frames. Although the glass was opaque and not very transparent, it allowed light in—a significant breakthrough. In southern Europe, wealthier villas sometimes used alabaster panels, which diffused light while shielding interiors from the sun.
The Middle Ages: Stained Glass and Simple Openings
Medieval windows were modest, mirroring the simplicity of life at the time. In castles and homes, narrow openings served as windows, secured by wooden shutters or planks. Gradually, small glass panes began appearing in wealthier buildings, primarily churches, where stained glass techniques flourished. These stained glasses, colored with natural minerals, had vibrant, unique hues. The oldest surviving stained glass, from the Saint Denis monastery in France (9th century), inspired Gothic architecture, which prominently featured large, colorful windows.
Residential houses usually lacked glass in their windows, as panes were a luxury few could afford. Interestingly, thinly scraped animal skins were also used, which allowed light in but did not provide transparency. Over time, through trade connections, European artisans began producing their own, larger glass panes.
Renaissance and Baroque: The Window Revolution in Full Bloom
The Renaissance and Baroque periods saw a breakthrough in glass-making technology, enabling larger panes. This era saw the advent of rolling techniques, producing clearer glass for large, decorative windows. During the Renaissance, particularly in Italy, architects like Palladio promoted concepts of bright, spacious interiors with large windows. The Baroque period brought richly decorated frames and more light into palace interiors. Casement windows, composed of multiple small panes in a single frame, emerged as a more economical solution, avoiding the need for large, costly glass panes.
The 19th Century: The Industrial Revolution and Mass Glass Production
The Industrial Revolution transformed the window market, with the invention of rolled glass and flat glass production methods, enabling mass production even for working-class buildings. Metal window frames, especially iron and steel, allowed for larger, more stable structures. Factories and industrial buildings often used large windows for natural light.
Glass was no longer solely a luxury but gradually became widespread. In the United States and Western Europe, windows were installed in almost every home, symbolizing modernity. Tempered glass, introduced in the mid-19th century, was stronger and safer, becoming common in public spaces.
The 20th Century: Thermal Insulating Glass and PVC
The 20th century brought another revolution in window technology—the production of thermal insulating glass. Double glazing, invented in the 1930s, effectively insulated interiors, retaining warmth and reducing heating costs. Urbanization increased the demand for windows that improved thermal and acoustic comfort in residential and office buildings. In the 1960s and 70s, low-emissivity (Low-E) glass was introduced, reflecting heat and enhancing insulation, becoming a standard in modern construction.
New synthetic materials, such as PVC, revolutionized the window market, offering lightweight, durable, and weather-resistant options. PVC windows became popular for their lower production and installation costs and ease of maintenance.
Contemporary Times: Smart Coatings and Next-Generation Windows
Today, windows are no longer just light sources. Thermal insulating and solar control coatings are widely used to enhance thermal insulation and block UV rays, reducing the risk of overheating interiors. Modern windows are designed with energy efficiency in mind—triple, quadruple glazing, and special coatings dynamically adjust light transmission based on external conditions, often integrated into intelligent building management systems.
Future technologies include electrochromic glass, which automatically darkens under sunlight, and photovoltaic glass that can generate electricity. Windows can serve functions beyond what early artisans could have imagined—regulating temperature, conserving energy, and enhancing occupant comfort. Looking through a smart window today, one can see the remarkable journey of this technology.
At Bertrand, this window revolution is also evident, thanks to a nearly 60-year tradition. Over this time, windows have certainly evolved, and we’ve learned a great deal. One of the more modern technologies available in Bertrand’s offerings is Infratherm, a glass pane with a heating function.
It leaves us wondering—what’s next? What will the windows of the future look like? We’re just as curious.