Webinar in brief: Insulation 101, the science behind insulation

13 April 2021 Kingspan Insulation Asia
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Insulation is an important factor to consider when designing any building. It is vital to understand how and why insulation is used and the many benefits associated with it.

 

As with most scientific topics, there are quite a few key terminologies, equations and definitions to understand and insulation is no different. To fully understand insulation, how it occurs and the benefits of insulating a building correctly, Kingspan Digital Academy produced an Insulation 101 webinar explaining the need to know basics.

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As you know heat moves from warmer areas to colder areas through heat transfer. This movement is what causes buildings to get colder in the winter (heat leaks out from a building into the colder environment outside) and hotter in summer (heat moves from a warmer environment outside into a building). This movement occurs by one of three methods; conduction, convection and radiation.​

 
  1. ​​Conduction is how heat transfers along or through a material from one place to another.
  2. Convection is how heat moves through liquids and gases. This occurs when the molecules of a liquid or gas heat up as their density changes. This change leads to warmer air becoming less dense and rising.
  3. Radiation is the transfer of heat as energy from one body to another across space. The rate of heat transfer is controlled by temperature, distance and emissivity.

Thermal insulation works by restricting and resisting how heat transfers by these methods. All materials allow a measure of heat to pass through them, some with less resistance than others.
 

Insulation materials provide considerable resistance to heat flowing through it. When these materials are installed, the heat flowing in or out of a building is reduced, thereby minimizing the need for conditioning. In terms of thermal insulation, different types of insulation deal with the transfer of heat in different ways.
 

  • Bulk fibre insulation works by limiting air movement, as still air is an effective insulator, it eliminates convection and has low conduction.
  • Rigid board insulation limits conduction, relying on either air or gas pockets to reduce the transfer of heat.
  • Reflective insulation reduces the amount of energy that travels in the form of radiation. Some forms of reflective insulation also have a conductional resistance layer to reduce air movement, or convection.  

There are many different insulation materials on the market, all of which can be broken into three main categories; inorganic, organic and other, each of which having a different application. The most commonly used insulation materials in the building and construction industry are; Thermo Cellular, Phenolic, PIR, XPS and Fibre Glass.

 
TYPE OF INSULATION DESCRIPTION PROS CONS
Thermo Cellular Polymer air-cellular or closed-cell foam core sandwiched between two layers of highly reflective aluminium foil
  • High performance in thin profile
  • Fibre-free and non-allergenic
  • Vapour-permeable or vapour barrier
  • Rodent and water-resistant; unaffected by moisture
  • Some provide thermal break
  • Lower convective heat resistance
  • Requires reflective air space
Phenolic Board High performance rigid thermoset core sandwiched between composite facings
 
  • CFC/HCFC-free with Zero Ozone Depletion Potential (ODP)
  • Ultra-low conductivity = Highest R-value per mm
  • Fibre-free insulation core
  • Less smoke
  • Vapour barrier
  • Suitable only for envelope applications
PIR Board High performance, fibre-free rigid urethane resin insulation core
 
  • CFC/HCFC-free with zero Ozone Depletion Potential (ODP)
  • Fibre-free insulation core
  • Board strength
  • Vapour barrier
  • Lower thermal performance than phenolic foam
  • Dense smoke released in a fire
XPS
 
High performance, closed cell rigid board
 
  • High conductivity
  • Water resistant
  • High compressive strength
  • Lower thermal performance than phenolic foam
  • Melts, softens, and gives off thick black smoke in a fire

 
Fibreglass Spun molten rock fibres bonded with resin
 
  • Non-combustible - low density products
  • Easy to cut
  • Combustible – high density products
  • Fibres (allergenic)
  • Settles, slumps
  • Absorbs moisture
  • Requires supporting structure (framing) which leads to thermal bridging
It is also important to understand how the effectiveness of thermal insulation is measured. Insulation is rated in terms of thermal resistance or R-Value (R). This value measures a materials ability to resist the flow of heat. The higher the R-Value, the greater the insulating effectiveness which depends upon the material, its thickness and its density. Total System R-Value (RT ) is the total resistance of a building element and takes into account the resistance provided by all of the building materials used in a wall, roof or ceiling.
 
In addition to thermal resistance, the thermal conductivity and thermal transmittance of materials is also measured. Thermal conductivity is measured by the K-Value (λ) or lambda value. This is the ability of a material to conduct heat, meaning the lower the K-value, the better the material is for insulation as less heat is lost. The U-value measures the amount of heat that is transmitted by the insulation material, known as thermal transmittance. For insulation, the lower the U-value, the better the insulation performance.
 
Thermal bridge and continuous insulation
The elements of a building make up the building envelope (the material that encloses your building). For insulation in the building envelope to reduce heat loss, it must have as few thermal bridges as possible.

Thermal bridging occurs as heat transfers across building elements, moving from hot to cold spaces by the path of least resistance. These paths occur in the breaks of a buildings thermal envelope, such as through framing. High thermal bridging means a less energy efficient building, as energy is lost via these bridges.



Adding a thermal break between building elements helps to reduce thermal bridging preventing heat flow. An effective thermal break is continuous insulation, as it helps to; slow the movement of heat through building elements, achieve greater energy efficiency and improve building performance.
 

With the basics of insulation now covered, please feel free to reach out to our Technical Services team on (+61) 448 39 2336 or email infokingspaninsulation.asia@kingspan.com with any enquires or concerns you may have about your next project.

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