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What Is Insulation?
Perth Insulation is a material that limits the transfer of heat to reduce energy usage. It also helps protect machinery and people from overheating.
Various materials can serve as insulation. Some have the advantage of being eco-friendly and made from recycled materials.
Fiberglass and cellulose are traditional insulation materials that are placed between wood-frame framing like studs and joists. Loose-fill cellulose is also available and is blown into place with special equipment.
Insulation Materials
Insulation materials fall into two categories: natural and man-made. The insulation material you choose affects the performance of your home. The performance of your insulation depends on its ability to restrict conduction, convection and radiation.
Fiberglass is the most commonly used insulation material in both new and existing homes. It is made from fine glass fibers that are woven together to create an effective non-flammable insulation. This type of insulation is available in batts or rolls and can be installed between studs, joists or beams. It is important to follow safety precautions and building codes when installing fiberglass insulation.
Cellulose is one of the most eco-friendly types of insulation. This insulation is constructed from recycled paper products and may be blown or damp-sprayed. It is often combined with a mineral (rock or slag) wool to achieve better thermal performance. It is a good option for walls with high R-value requirements.
Polyisocyanurate insulation is another type of foam insulation that can be sprayed or poured. It is a closed-cell insulation that uses a low-conductivity gas inside the cells to reduce its thermal conductivity. It is available as liquid foam that can be sprayed on-site, or as foam boards with different facings to suit specific applications.
Spray and poured foam insulations are typically installed in walls, floors and attics. They are often combined with drywall to ensure that the studs and joists are properly filled with insulation. These types of insulation are a bit more expensive than other forms of insulation, but they have an excellent R-value that will lower your energy costs and help the environment.
In framed construction, full-fill cavity insulation is installed within the wall framing, which is more efficient than insulating an exterior wall or a wall with a vent space. The insulation should be installed before the cladding is applied to avoid voids and gaps that can cause air flow or condensation.
Slab insulation is similar to loft roll but slightly more rigid. It is a favourite for deep cavity insulation in walls and for situations where the space between the wall and the frame needs to be completely covered. This is a very durable and cost-effective insulation material that can last for decades and is resistant to moisture, rot, mildew and corrosion.
Conduction
Conduction is the way in which heat moves from hotter to colder zones. Insulation reduces and restricts this flow. It does this by reducing the transfer of energy between surfaces or materials that would otherwise be in direct contact and by blocking the different methods of heat transfer such as radiation and convection.
Conduction happens when atoms in adjacent molecules of a material collide. This causes them to vibrate and the vibrations transmit thermal energy across the material. This process is more prevalent in solids and liquids than gases because the atoms are closer together. A material’s ability to conduct energy is determined by its temperature and its thickness. The greater the difference in temperature between the two materials the faster the transmission of heat. This is known as a material’s thermal conductivity and it is defined by its l (lambda) value.
Insulating materials differ in their ability to conduct heat through them, with some being much better at this than others. The lower the thermal conductivity of an insulation the more efficient it is.
The l value of a construction material is determined by dividing its thermal conductivity by its thickness. This is then multiplied by the factor 1/lambda to provide its R or U value. A higher R or U value means the insulation is more effective at reducing heat transfer.
In addition to reducing heat transmission, insulation also blocks the transfer of water vapour, which is important in coastal climates. This is especially important because if moisture is trapped under insulation it can cause corrosion in the metals of heating and cooling systems as well as other structural elements. To prevent this from happening insulation must be properly installed, with a water-proof barrier on the outside and a permeable lining to allow the water vapour to escape.
Convection is another common form of heat transfer. This is when warm air rises and cool air sinks, creating a current of circulation that keeps the surface on which it is resting warmer. This is why the top few inches of a pool feels warmer than the bottom. It is also why an insulation material needs to be water proof if it is to be effective against condensation and mould growth.
Convection
When it comes to thermal insulation, materials that are dense and slow to conduct heat make good insulators. Likewise, materials that conduct heat very quickly have poor insulating capabilities. Insulation works to reduce heat transfer by reducing conduction, radiation and convection. The best insulation is incorporated into buildings at the time of construction, but can be added later during renovations as well.
The most common types of insulation are bulky fiber materials such as fiberglass, rockwool and cellulose that trap air or another gas in their cells to resist conductive heat flow; rigid foam boards that create an air barrier in a building cavity; and highly reflective foils used in radiant barriers and energy efficient insulation systems. The range of products also includes sprayed-on polyurethane and spray-on cellulose insulation.
Bulk insulations resist conductive heat flow in the walls, ceiling and floors of a home. Rigid foam insulation is especially effective as it prevents heat flow in both directions. It can be installed in both new and existing homes, although it’s better to install it during construction so that the building is fully sealed and insulated.
Insulation can be categorized by its resistance to heat flow, or R-value. The higher the R-value, the more effective the insulation. However, it is important to consider other factors when selecting insulation for a home, including indoor air quality impacts, life cycle costs and recycled content.
A material’s R-value can be determined by measuring the amount of heat it transmits per unit of time through its surface area. However, this doesn’t account for the fact that different types of insulation have differing efficiencies in terms of how much heat they retain after transmission through their surface area. For this reason, the R-value of a particular type of insulation cannot be relied on to provide an accurate comparison of one product to another. In addition, a high R-value doesn’t necessarily mean that an insulation is suitable for a specific climate. For this reason, it’s important to understand the physics of how insulation works before choosing the right product for your home.
Radiation
Insulation refers to materials that reduce the transfer of heat, cold, electricity or sound between bodies that contact each other. You can think of a thermos of hot chocolate staying warm in your hands or an ice chest keeping sodas and food cool at the beach as examples of insulation. Insulation also creates barriers that stop the transmission of radiation from one body to another.
For example, the ionizing radiation that is emitted by a radioactive element is stopped when it penetrates lead or any other dense material. This type of radiation is dangerous in high doses, but in smaller amounts it can be useful for medical imaging, x-rays and other uses. Insulation also stops the spread of sound, as it decreases the level of airborne and structure-borne noise that can travel between rooms or floors.
Bulk insulation uses pockets of air trapped within it to resist conductive and convective heat flow. Its effectiveness depends on the thickness and density of the material, but the R-value of most insulation increases as these qualities increase.
Reflective and radiant barrier insulation use highly reflective surfaces to slow the transfer of heat by reflecting it back away from living spaces. These systems are most effective when kept clean, as dirt and dust can significantly reduce their performance. They are typically made from shiny aluminum foil laminated to paper or plastic and available as sheets (sarking) or concertina-type batts.