Wall insulation systems help to keep homes more energy-efficient and comfortable. According to Energy Saving Trust, "If your home was built from 1920 onwards, the chances are that its external walls are made of two layers with a small gap or 'cavity' between them." This empty cavity is what led to the need for insulating material. There are many advantages, as well as disadvantages, that accompany wall insulation.
Advantage—Energy Efficiency
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Unlike conductors, insulators are poor transmitters of heat. This characteristic explains why wall insulators are energy-efficient. They slow down the rate of heat transfer and restrain heat within the house as long as possible; hence, there is less of a need to use energy to achieve and maintain a comfortable room temperature, especially during winter. Since wall insulators prevent heat loss, they save on energy costs. Wall insulators also prevent the penetration of too much heat from the external environment, which is especially useful during summer.
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Advantage—Friendly to the Environment
Wall insulation is normally made up of air barriers, vapor retarders and thermal bridges--all of which contribute to preventing heat from escaping through the walls of homes. By reducing heat loss, as well as cool air that is lost during the summer, wall insulation reduces emissions to the environment by reducing the use of heaters and air conditioners, which helps to reduce electricity consumption. As the majority of power plants that produce electricity also produce carbon dioxide, lowering energy consumption can reduce pollution. According to Green Street, "Wall insulation can reduce heat loss by up to 40% through cavity walls and up to 60% through solid walls. It is therefore one of the most important energy-saving measures to consider."
Advantage—Noise Reduction
Insulating walls also reduce noise. Insulators between walls act as absorbers and barriers to decrease noise being carried to adjoining rooms.
Disadvantage—Rain Penetration
According to the Building Research Establishment, cavity wall insulation does not totally prevent rainwater from penetrating the "outer leaf of masonry." The rainwater creates moisture which then causes "dampness on internal finishes."
Disadvantage—Health Risks
Some materials used for wall insulation pose health risks. Asbestos, for example, has been known to cause mesothelioma, a form of lung cancer, and gastrointestinal tract cancers. Fiberglass, a commonly used material for insulation, can cause skin allergies due to the chemicals used to bind the fibers together.
In addition, styrene, a foam insulator, can cause health risks—ranging from eye and respiratory irritation to possible effects on the liver and the reproductive system.