Insulation keeps temperatures steady, provides acoustical comfort and reduces energy costs. Its effectiveness is wholly dependent on science, technology, engineering and math disciplines.
Any material that prevents electricity, heat or cold from easily passing through it is an insulator. Wood, plastic, fiberglass and foam are good examples of insulators.
Heat Transfer
Insulation keeps homes and commercial buildings comfortable, acoustically sound and energy-efficient. Although it may seem like a simple technology, it relies on skills from STEM (Science, Technology, Engineering, and Math) disciplines to reduce the flow of heat energy.
Heat moves through materials by conduction, convection and radiation. Insulation acts as a barrier that minimizes transfer of thermal energy between different materials. It can do this by decreasing conduction, convection and radiation or by reflecting radiant heat back to its source.
For example, when an insulated attic is properly installed, it prevents hot air from rising to the ceiling and cold air from escaping the roof. This keeps the room below it much warmer in winter, and reduces the amount of energy that is needed for heating that space.
It is important for homeowners to understand the science behind insulation so they can choose the right product and R-value for their home or commercial building. Different parts of the home need different R-values to combat the dynamics of heat transfer. The attic needs a higher R-value to combat hot-to-cold conduction, while the walls need insulation that prevents indoor heat from escaping.
Most Insulation companies sell rolled Fiberglass at Home Improvement stores and for new-construction projects, however Cellulose (paper products) is becoming the preferred choice due to it’s superior performance and lower cost. Some installers even use a machine to “fluff” the material and make it more dense, which makes it much more effective than rolled Fiberglass.
Conduction
In conduction, a material’s molecules vibrate and transfer kinetic energy to their neighbors. The kinetic energy makes the molecules in adjacent layers of the material hotter, which eventually causes them to reach a common temperature. This is how a metal pan gets hot when you place it over an open fire. This type of heat transfer is why it is so important to use a potholder when handling hot pots and pans.
Insulation materials are rated according to how well they resist conductive heat flow. This is known as their R-value. The higher the R-value, the more effective the insulation is. R-values can vary based on the type of insulation, its thickness, age and moisture content. Some manufacturers also post technical data sheets on their websites that provide information about an insulation’s R-value.
The R-value of an insulation is determined by a mathematical formula involving the thermal conductivity and thickness of the material. It is similar to Ohm’s law for electric current, with temperature doing the role of electric potential. Materials that allow heat to pass through them easily are considered good conductors; metals, for instance, have high thermal conductivity. Substances that stop the flow of heat are called insulators, such as plastics, glass and air. This is why it’s so important to have an efficient insulated home!
Convection
Insulation slows the movement of heat from warm to cool areas, saving energy and reducing heating and cooling costs. It also reduces acoustic levels and helps systems work more efficiently. While it may seem simple, there’s an enormous amount of science and engineering involved in the proper application of insulation. Its success relies on understanding the three dynamics of heat flow; conduction, convection and radiation.
Conduction is the transfer of thermal energy from hot to cold materials through molecular transport, such as when a spoon placed in a cup of coffee conducts heat from the handle to your hand. In the building industry, conductive elements are metals, liquids or gases. Insulation inhibits conduction by separating conductive layers from each other.
A natural phenomenon where lighter, warmer air rises and cooler, denser air sinks occurs in buildings, homes, and even on Earth’s oceans. Natural convection can cause significant airflow problems if not properly addressed through insulation. It is a key reason that engineers take the insulating qualities of materials into consideration when designing structures.
Plastic foams like polystyrene and insulation made from recycled glass and fibreglass are excellent insulators because they have small air pockets that trap thermal energy. They are also good insulators because they have low thermal conductivity, the property that measures how fast energy travels through a material (W/mK or lambda value). It is the inverse of thermal transmittance which is what you want to minimize when evaluating insulation products.
Radiation
Radiation is energy that comes from a source and can be in the form of heat or waves. It can travel through space and can be able to penetrate various materials, depending on its type. There are different types of radiation with different energies, such as light or microwaves, x-rays from an x-ray machine and gamma rays from radioactive elements. Energy levels of the radiation are described by their ability to ionize matter (ionizing radiation). When high doses of ionizing radiation are used incorrectly or in excess, it can cause harmful effects on living organisms such as cancer. This is why specific safety measures and standards are put in place to ensure that people, plants and animals are protected when this kind of radiation is present.
When radiation passes through living tissue, some of it can be absorbed into the cells. The amount of radiation energy absorbed per unit of matter is known as the absorbed dose and is measured in units called rems or grays (Gy). The type of radiation also affects how much damage is caused, with alpha particles being more damaging than beta and gamma.
Radiation is all around us, but it usually has very little effect on humans at low doses. This is because the body has defense mechanisms to protect against it, and even at higher doses, the body can repair any harm that is done.