What defines a window?
Windows are so commonplace now, that you may think that the meaning of the word is obvious.
The Oxford Dictionary defines a window as: “an opening in a wall for light and air, typically filled with glass”.
But, the word “window” as we know it today, didn’t exist until the 13th century. Before that it was literally “hole in roof”.
Originating from the old Norse word “Vindauga”, meaning “wind eye”, windows were initially created for ventilation. At this point they were unglazed openings in roofs functioning as “smoke holes” to allow a breathable atmosphere when fires were used for cooking and heating in primitive homes. We bet that made them pretty draughty though!
Nowadays, we are less willing to share a one room hut with our livestock for warmth (it would definitely be too tricky to get rid of the smell for the next time the in-laws came round to visit!) Therefore, our definition has developed to “hole in wall with glass”. Why? Because the function has changed. Now windows are for letting light in and being able to see out, all whilst keeping the heat inside.
Where did windows come from?
Windows likely have existed in some sort of form since the stone age. At first, those holes weren’t in walls at all but in the roof, above a central fire. They let smoke escape and allowed a little light to filter in, making early shelters more liveable. As people learned to build stronger walls, they began adding smaller openings at eye level, turning simple smoke holes into the first recognisable windows.
The thought process probably went something like this:
“Dark.”
“Hole. Light come in.”
“Good.”
Those early “windows” were nothing like the framed glass panes we know today. They were rough openings, for example small gaps in stone or mud walls, or holes cut into animal-hide shelters. In colder regions, people might stretch animal skins or thin hides across them to block wind and rain, while still allowing some light through. In warmer areas, they were often left open entirely.
Every civilisation since has created its own form of window, shaping it, glazing it, and improving it with each generation.
How have windows changed over time?
Over time windows would slip down from roof to wall and would provide a whole new utility: sight.
Now a means to look outside, people would use them to spy on your neighbours, or to see a raid occur on your village and react accordingly.
As windows developed so did our attitude towards them. A window became an eye to the world, but it worked both ways: if you could look out, someone else could look in.
Consequently, people began finding ways to control light and maintain privacy using available materials. In Egypt, they wove reed mats to block the sun and protect homes. Later, the Greeks introduced wooden shutters; other societies developed local variations. These ideas endured for centuries and still shape how we cover windows today.
Over time, people experimented with different materials as makeshift blinds, including oiled cloth, paper shutters and thin sheets of animal horn. Many of these coverings were used by ordinary citizens in England during the 16th century.
As glazing developed, most windows still lacked glass. It remained expensive to produce and was reserved for the wealthy. Resultingly, glass became a symbol of status, marking homes of high standing. This divide deepened with the introduction of the window tax in the late 17th century, when having more windows meant paying more. As production improved and costs fell towards the end of the Tudor era, glass gradually became more accessible, though many homes still went without.
The Invention of Glazing
The Romans are usually credited with inventing glass windows, possibly as early as 400 BC, though definite examples appear by around 100 AD. Once they discovered how to make clear, transparent glass, they quickly realised it could do more than hold wine – it could let in light while keeping out the weather. And so, glazing was born.
Before that, early glass was thick, uneven and more decorative than practical. It wasn’t something you could see through clearly. Think of it less as a window to the world and more like a fogged bathroom mirror.
When was glass invented?
Glass itself came long before the Romans. Nature made the first kind in the form of volcanic glass, which ancient people shaped into blades and arrowheads. You may have heard it called Obsidian.
Man-made glass was an accident. Around 3500 BCE, metalworkers in Mesopotamia noticed that sand melted and fused into a shiny, translucent material when exposed to intense heat. They had discovered glassmaking… quite by mistake.
Later civilisations such as the Egyptians refined it, adding metal oxides like copper and cobalt to produce vivid colours. These bright beads and amulets became prized decorative items long before anyone thought to stick them in a wall.
By the time the Romans encountered Egyptian glass, they saw its potential and took the craft further than ever before.
When was glass first used for windows?
Enter glassblowing, the Roman innovation that changed everything. By blowing air into molten glass, they could create thinner, more uniform sheets. The technique still wasn’t perfect; early panes were small, slightly opaque and often tinted green or brown. But they were enough to start a trend among Rome’s wealthy elite.
Roman villas soon featured glazed openings, bringing in soft light and keeping out dust and noise. Each pane was cut, flattened and polished by hand, which made them expensive. For everyone else, horns, parchment or thin cloth still did the job.
When the Romans brought their empire (and their glass) to Britain, they left traces of small workshops, such as those at Wearmouth and Jarrow around 680 AD. By the 1200s, glassmaking had spread across England, particularly in Surrey and Sussex.
As Christianity rose, glass gained a spiritual purpose. Stained-glass windows filled churches with coloured light, turning stories into shimmering artwork. One of the earliest surviving examples in England is at St Paul’s Monastery in Jarrow, dating back to 686 AD – proof that once people discovered glass, they couldn’t stop finding ways to use it.
Who had glass windows?
For centuries, glass was a luxury item. Fragile, costly and time-consuming to make, it was reserved for the wealthy, the powerful and the pious. Palaces and cathedrals gleamed with colour while ordinary homes relied on wooden shutters or cloth screens.
Having glass windows became a symbol of success. The more panes you had, the higher your social standing. That is, until 1696, when King William III introduced the window tax. The idea was simple: more windows = more tax. People were furious and some even bricked theirs up in protest. Fun fact: that’s how the phrase “daylight robbery” was born.
The tax lasted until 1851, but its effects lingered. Even today, you can still spot the outlines of bricked-up windows on Georgian terraces.
And yet, for the wealthy, windows remained a statement. Take Hardwick Hall: built in 1590 for Bess of Hardwick, one of the richest women in England. Locals famously said it had “more glass than wall” – a perfect brag if there ever was one. This inspired the name of our Hardwick Flush Casement!
How has the appearance of window glass changed?
Early glass was far from perfect. It was cloudy, bubbled and often uneven in colour. Over time, new methods improved clarity and consistency:
- Slab glass: molten glass poured onto a flat surface – rough but functional.
- Cylinder glass: developed in 11th-century Germany. Craftsmen blew a large glass bubble, cut it open, reheated it and flattened it into a sheet. The result was clearer but still slightly wavy.
- Crown glass: perfected in the 17th century. A molten bubble was spun rapidly into a large disc, then cut into diamond-shaped panes. If you’ve ever noticed the circular “bullseye” pattern in old windows, that’s crown glass.
Each advancement brought smoother, larger panes, slowly transforming glass from a luxury to a standard building material.
What are Sash and casement style windows?
With clearer glass came creativity. By the 17th century, window design became an art form.
The sash window, invented in the late 1600s, allowed panels to slide up and down (or sideways in Yorkshire’s case). It became a hallmark of Georgian and Victorian architecture, loved for its symmetry and elegance.
A century later came the casement window, hinged to open outwards. Simpler to build and easier to clean, it became common in rural cottages and modern homes alike.
Both styles – sash and casement – are still popular today, especially in heritage projects where their classic proportions fit seamlessly with period façades.
How have window styles evolved to suit different types of homes?
As buildings became more varied in size, shape and purpose, windows evolved to suit them. Different styles reflected not only available materials but also social trends and architectural fashions of the time.
Sash windows
By the late 1600s, sash windows had become the defining feature of grand Georgian townhouses. Their vertical sliding design allowed for ventilation without letting in rain (clever, considering Britain’s weather record). The equal, symmetrical layout suited the balanced façades of Georgian and later Victorian architecture.
The classic vertical sliding sash became a symbol of elegance and proportion, found in terraces, manor houses and later, period conversions. In northern regions like Yorkshire, the design evolved into a horizontal sliding sash – also known as the Yorkshire slider – which worked better for wide, low openings and could handle strong crosswinds without rattling.
Casement windows
Casement windows, which hinge open like doors, have an even longer history. They were the norm in medieval cottages and farmhouses, where smaller, irregular openings made side-hinged designs more practical. Casements could be propped open easily to let in light and fresh air while keeping the structure simple.
Hopper windows
The hopper window, which opens inwards from the bottom, appeared later and became popular in industrial and institutional buildings of the 19th and early 20th centuries. Factories, schools and hospitals favoured them because they provided excellent ventilation without rain blowing in.
In domestic settings, hoppers were often used in basements or high-level openings, particularly in Victorian townhouses, where space was tight but airflow was essential. Their simple, inward-opening design also made them easy to clean – a small but significant perk.
How have Window Frames Changed?
Before aluminium and PVCu entered the picture, frames were made almost entirely from timber or stone. Medieval castles and churches often featured thick stone mullions, while houses relied on wood: strong, renewable and easy to work with.
For centuries, timber was king. It remained so until industrial materials took over in the 20th century. But now, timber is making a comeback, thanks to engineered species that last longer and require minimal maintenance.
How have attitudes to windows changed?
Originally, windows were purely functional – simple openings for light, air and the occasional bit of neighbour-watching. As glazing improved, they became decorative, even symbolic. Stained glass transformed them into storytelling tools for the church, while the grand homes of the Victorian era turned them into status symbols.
Today, our priorities are very different. We expect windows to look beautiful and perform flawlessly. The focus has shifted from appearance to performance: thermal efficiency, acoustic comfort and sustainability.
We want windows that:
- Keep warmth in and noise out.
- Stay secure without looking industrial.
- Last for decades without endless maintenance.
- Contribute to a low-carbon, sustainable home.
Modern glass is engineered for energy savings and comfort. Triple glazing, vacuum glazing and improved coatings mean today’s windows outperform anything seen before.
Why are timber windows making a comeback?
We’ve come full circle. The future of windows looks remarkably like the past – just a lot smarter.
Timber has returned to prominence thanks to modern engineering. Accoya and Red Grandis, for instance, are scientifically enhanced to resist rot, warping and pests while maintaining that unmistakable natural beauty. They outperform plastics and metals in longevity, insulation and sustainability.
Engineered timber also aligns with the global push towards carbon neutrality. It stores carbon rather than emitting it, helping reduce a building’s environmental footprint.
Combine that with innovations like vacuum glazing, and you have the best of both worlds: timeless craftsmanship and cutting-edge performance. Windows that echo history yet meet the demands of tomorrow.