How Does Insulation Work?

How does insulation work?  The answer depends on the type of insulation in question. However, understanding how insulation works will help you when selecting the right product for your project and the desired result you want to achieve.

Insulation generally refers to products to control heat flow (thermal insulation) or sound waves (acoustic insulation) between the outside and inside, or 2 areas within a home or commercial building.

Thermal Insulation:

Thermal insulation works by preventing all 3 types of heat transfer mechanisms, radiation, convection and conduction. To understand how insulation works it is useful to understand the difference between these 3 heat transfer mechanisms. Click on each for an explanation.

How a building heats up:

Heat energy transfers from warmer to cooler until there is no longer a temperature difference, and counteracting all 3 heat transfer mechanisms is beneficial when insulating a building. Each day as the sun comes up it beats (radiates) down onto a buildings roof, the tin or tiles begin to absorb this radiated energy and heat up. As tin or tiles are both very conductive materials, this heat energy quickly travels (conduction) from the top side of the roof to the underside of the roof where it is either given off as radiant heat or conducted into other parts of the building assembly that it is in contact with, for example the building frame / roof trusses. As the hot roof radiates heat into the ceiling cavity, all other elements, like the air within the loft and the plasterboard ceiling between the loft cavity and living spaces begin to absorb this heat energy. Eventually the plasterboard ceiling heats up and conducts heat from the attic and begins to radiate that heat into the living space and so the living space heats up. The purpose of thermal insulation is to slow down this process and minimise the heat that is radiated into the living space.  Different insulation products work to reduce this heat in different ways.

how does insulation work

Reflective Insulation – The first line of defence:

Reflective insulation or foil insulation is usually installed just below the tin or tile roof. Reflective foil insulation has very low emissivity properties, meaning that it only emits around 3% of the radiant energy that hits it. So of all the radiant energy that hits the roof, only 3% will be radiated into the ceiling space if reflective insulation is correctly installed. It is important to note that for reflective insulation to work it MUST be installed with an adjacent air gap. Even with reflective foil insulation installed, because 3% of the heat energy is still radiated into the ceiling space, the air and plasterboard ceiling will eventually still heat up. which is why we install a second line of defence.  

Bulk Thermal Insulation:

When bulk insulation in the form of batts, rolls or even loose fill fibres is installed between the rafters in the loft space, it works to slow down the conduction of heat from the hot loft space to the cooler living spaces or vice versa in winter. Bulk insulation contains millions of tiny little pockets of air. Air is a bad conductor of heat. So the more bulk insulation the longer it takes for the heat in the hot loft space to conduct through to the underside of the plasterboard ceiling, and then be radiated into the living space.   The R-Value on bulk insulation is effectively a measure of how slow heat will be conducted through the insulation. The higher the R-Value, the longer it take for heat to be conducted through the product and consequently, the better the product will be at insulating. That’s how thermal insulation works. To know more about how acoustic insulation works, visit ‘How Acoustic Insulation Works’ For more information on insulation products or to get an obligation free quote, call Higgins Insulation on 1300 130 233 or email

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