The History of Home Insulation

Insulation works by stopping the transfer of heat from one material to another. This keeps warm air generated by a heater from escaping through windows, walls, and ceilings, or keeps cool air generated by an air conditioner from being warmed by outside air entering the house.Ancient Egyptians were the first to use asbestos for housing insulation and they also used it for clothing and table wares. Ancient Greek and Roman houses invented cavity walls for insulation. These walls are created by building two stone walls, leaving a channel of air in between. Air is a natural insulator, so this trapped air kept the heat generated by fires inside the houses. Strips of cloth were also used in the Middle Ages and again in the Great Depression in America to trap moisture and stop drafts.  Cavity walls were rediscovered in the 19th century and were used to build houses in Europe and America. Rock wool would be placed into the cavities to provide insulation. Asbestos was also used in this way until the 1970s when the harmful health effects of asbestos were discovered. Asbestos is no longer used in home insulation as it can cause a rare type of cancer. Because energy costs were low in the earlier part of the 20th century, houses were sometimes built without proper insulation. Even in the 1950s, houses were often built with single layer walls of solid masonry and single pane glass windows. Without insulation, these types of buildings allow heat to escape quickly through the walls and windows. Today, energy prices are much higher, so all houses must be built with proper insulation to keep energy costs down. Many homes use fibreglass or expanding polystyrene foam inserted into cavity walls as insulation. Fibreglass is so effective because it traps air in between the glass fibres and this air stops the transfer of heat. With today's emphasis on making homes as eco-friendly as possible, insulation is important because it contributes to energy efficiency. Materials such as paper cellulose, recycled cotton denim, and sheep wool are eco-friendly options that are used to fill cavity walls. Making sure that a house is properly insulated, with no leaks or installation problems, both saves on energy costs for the homeowner and reduces the demand for energy production.