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The history of thermal insulation

triangle shelter as an old method of insulation


The history of thermal insulation is not so long compared with other materials, but human beings have been aware of the importance of insulation for a long time. In the prehistoric time, human beings began their activity of making shelters against wild animals and heavy weather, human beings started their exploration of thermal insulation.


 Prehistoric peoples built their dwellings by using the materials of animal skins, fur and plant materials like reed and flax.

          These materials were first used as clothing materials,first human body insulation because of their dwellings were temporary, they were more likely to use the materials they used in clothing, which were easy to obtain and process. The materials of animal furs and plant products can hold a large amount of air between molecules which can create an air cavity to reduce the heat exchange.

Later, human beings' long life span and development of agriculture determined that they needed a fixed place of residence, earth-sheltered houses(structure  with earth (soil) against the walls, on the roof, or that is entirely buried underground)., stone houses( first bungalow constructed in Ooty (India)), and cave dwellings began to emerge. 

Both earth-sheltered houses and cave dwellings were built at the same time and it appears they were very popular because of their inherent benefits.

Their implementation was cheap and an earth covering assured excellent protection against wild animals,fire and during periods of fighting. In addition earth houses use soil as a magnificent insulating blanket, as due to the high density of earth, the inside temperature changes very slowly. This phenomenon is called thermal lag which is why earth covering keeps the interior warm in winter and cool in summer.

In the 12th and 13t h centuries northern Europeans were building thatched houses with 60-80cm thick straw roof construction, and walls were often built of clay and straw. The dry,hollow fibre of straw and reed provided an excellent level of thermal resistance, so thatched houses quickly spread especially in the northern parts of Europe and America

The high density of these materials can cause a time lag effect in thermal transfer, which can make the inside temperature change slowly. This effect keep inside of the buildings warm in winter and cool in summer, also because of the materials like earth or stone is easy to get, this design is really popular in many places like Rfirst human insulated houseussia, Iceland, Greenland.

Organic materials were the first available to build a shelter for people to protect themselves from bad weather conditions and to help keep them warm.But organic materials like animal and plant fiber cannot exist for a long time, so these natural materials cannot satisfy people's long-term need for thermal insulation. So, people began to search for substitutes which are more durable. In the 19th century, people were no longer satisfied with using natural materials for thermal insulation, they processed the organic materials and produced the first  insulated panels. At the same time, more and more artificial materials start to emerge, and a large range of artificial thermal insulation materials were developed, e.g. rock wool, fiberglass, foam glass.

Reed panels were first used in the 19th century as thermal insulation mainly in ancillary buildings. They were popular because they were impervious to decay but they had poor hygroscopic ability. At the beginning of the 20t h century reed panels appeared with bituminous coatings but they did not spread because of their flammability and unreliable quality .

In 1920 the American Celotex Company introduced insulating panels made of bagasse (a waste by product of sugar manufacturing). It was used as thermal insulation in home construction and in the manufacture of refrigerated railroad cars. Owing to their flammability, later one or both of the sides were coated with asbestos cement. The first attempts to produce flax panels for roof insulation were made in the USA.

Polystyrene foam was first made in 1931 in the USA. The Swedish inventor Carl Georg Munters (1897-1989) cooperating with John Tandberg (1896-1968) patented the method for foaming polystyrene. Applying their technology the first polystyrene foam was produced in 1941 by Otis Ray McIntire (1918-1996),an engineer of the Dow Chemical Company. He heated the milk-white polystyrene granulate up to 200˚C in an extruder using a chlorinated hydrocarbon (chloromethane) as a foaming agent.He led the polystyrene foam through a narrow aperture which re-sulted in  extruded polystyrene (XPS) panels with a 98% closed cellular structure. The first polystyrene insulating product was put on the market by the company in 1943 under the name of Styrofoam R.

The appearance of plastic foams (polystyrene, polyurethane)created a huge revolution in the market of insulation materials in the 1940s and 1950s. From this point on artificial insulation materials (plastic foams, mineral wool) overtook to force back the natural materials. After the oil crisis of the 1970s their spread accelerated and today artificial materials represent about 90-95% of the total thermal insulation material production.

Another technology – the expanded polystyrene foam (EPS) –was invented in Germany by the engineers of IG Farbenindustrie AG in 1950. Using pentane as a foaming agent the polystyrenegranulate is supplied with water vapour.As the temperature rises the grains of the raw material grow soft and the effects of the pentane results in a 20-50-fold increase in the volume of the pearls. During this action small closed cells arise inside, as a result of which, the expanded polystyrene foam has excellent thermal insulating capacity creating an ideal building insulation material.

Summarizing the development of thermal insulation materials we can separate five different periods of time. Each period started with a significant step in the historical development of humanity, science or industry. These were the main causes of change in the market of thermal insulation materials that resulted in the appearance of a new or disappearance of an old product.If we analyze the market for thermal insulation materials it is clear that the most popular products are the artificial materials. Mineral wool products represent about 50-55% and plastic foams about 40-45% of the total production.It became clear in the last century that the amount of fossil fuels is finite and they will be exhausted within a relatively short time. In addition the serious issue of the 21s t century, that of climate change and global warming results largely from the emissions of greenhouse gases (especially CO2)from the use of fossil fuels