In ancient times people insulated their homes using materials found locally. Subsistence motivated them to do whatever they could to retain heat and protect against harsh weather.
As technology evolved, so too did insulation. From the earliest vernacular materials, to cavity walls developed in the 19th century, and finally to spray foam insulating material of today.
Ancient Times
Insulation is a general term that describes materials that create barriers for transmission of heat, cold, electricity, moisture and shock between adjacent bodies. Building envelope insulation reduces energy consumption, improves indoor comfort and protects a home from damage caused by water and air leaks. It also promotes healthy indoor environments by reducing humidity and controlling indoor temperatures.
In ancient times, people used a variety of locally available materials to insulate their homes. Animal skins and furs were used in colder climates to keep warmth in, while clay and mud were popular insulation materials for arid regions because they offer thermal resistance and help regulate indoor temperatures. Straw and hay were also common insulation materials, as well as sod, turf and other dried plant materials like seaweed or reeds.
In the medieval era, which is also known as late antiquity or the Middle Ages (from Latin medi(um) + aev(um)), houses were built of stone and completed with thatched roofs. These houses were often drafty, damp and cold. To control their temperature, inhabitants hung tapestries and stuffed the walls with straw or mud mixed with plaster. The Middle Ages also saw the introduction of hollow or cavity walls, which can help reduce heat loss.
Medieval Times
The Middle Ages is a period of European history spanning from the fall of the Roman Empire in the 5th century to the start of the Renaissance in the 15th century. It is traditionally divided into three epochs: classical civilization, the medieval ages, and modern times.
During the medieval times, homes were often built of stone and wood with thatched roofs, which offered little insulation. This led to drafty homes that were cold and damp. To combat this, people hung heavy tapestries to keep out the drafts and add some flair to their home decor.
Another popular method of insulating their houses was by plastering mud in between gaps in the walls. This was called mud chinking. The mud was also believed to have cooling properties, which was beneficial in hot climates. Papyrus and reeds were also used for insulation, as they were lightweight and provided decent thermal properties.
By the late medieval era, cities were becoming more and more important economic centers for trade. This would eventually lead to a shift from feudalism and the growth of guilds. It was also around this time that a new architectural style, known as the Gothic, began to be used for church buildings. The taller church/cathedrals were built to impress and show off the wealth of the ruler. The Church became the major unifying cultural influence, and kings, queens and other leaders gained their power through ties with and protection of the Church.
Industrial Revolution
The industrial revolution brought a profound change to the history of insulation. As a result of new technologies and manufacturing techniques, homes began to be built with stone, glass and concrete rather than the earthen materials used in previous centuries. These new structures expand and contract more easily with temperature changes, leaving them exposed to a host of different challenges including moisture management and thermal comfort.
To deal with these issues, builders developed a variety of methods to help improve the insulation value of these new buildings. This ranged from putting bricks or blocks between the walls of a building to creating the cavity wall that we still use today to keep heat in and cold out.
This period also saw the development of asbestos as an insulation product, first patented in 1828. It was originally used to wrap pipes and provide a fireproof barrier around boilers. The material became incredibly popular because it was cheap and easy to use. However, as it ages, it becomes crumbly and can release hazardous asbestos particles into the air.
Modern insulation technology has continued to evolve over the years. Some of the most important innovations include mineral wool, which is created by spinning silica or glass into threads, and plastic foam, which has revolutionized home insulation with its ability to be cut to size. Both of these products can block conductive heat transfer as well as convective flow, which is the movement of air from heated to cooler areas of the building, while allowing for natural light to enter.
Modern Times
With the advent of modern technology, insulation has become more efficient. Today, we use a variety of materials to create comprehensive thermal barriers in our homes, preventing air leakage and reducing energy usage. This is known as a building envelope and includes walls, floors, roofs, and crawl spaces. Current best practices also include sealing and upgrading existing insulation to meet modern building codes and optimize energy efficiency, indoor comfort, and sustainability.
Until the 1930s, most houses were uninsulated. Then came fiberglass, which was developed by accident by Dale Kleist as he was trying to make glass blocks. Kleist found that melted glass could be made into thin fibers when it was shaped and exposed to high-pressure air. These new fibers offered improved thermal resistance and were not subject to flames or smoke, making them ideal for home insulation.
Cellulose was another new insulation material that rose to popularity in the 1940s. This product was made from recycled paper, newspaper clippings, straw, sawdust, and cotton, but wasn’t widely used until manufacturers discovered how to make it flame retardant.
Asbestos was also popular in the early 1900s, but it became less common as people learned of the health risks associated with exposure. Today, most residential builders prefer to avoid this hazardous material and instead use mineral wool or other alternatives. Fiberglass and cellulose continue to be among the most popular options for insulation. But there are many other insulation materials available as well, including foamed-in-place products like phenolic, which can be installed in homes to meet the latest building code requirements and optimize energy efficiency, temperature regulation, and indoor comfort.