How Does Insulation Work?

How does ceiling insulation work?

These days, most people understand that insulation is an important component of any home or commercial building. But how does insulation work? To put it briefly, thermal insulation is made of materials (such as glass wool or polyester) that are good at slowing down the path of heat.

In this article, we’ll explain what insulation does and the science of how it works. There are many different types of insulation products and understanding how they work can help you choose the best product for your needs.

Does Insulation Help With Heat?

You might have heard that insulation helps keep the warm air inside your home during winter, but what about summer? Does insulation help when there is a high temperature outside? It sure does.

A material that is a good insulator works both ways. Whether the heat is on the outside or the inside of your home, insulation acts as a barrier to the flow of heat. That means heat can’t escape as fast during winter and it can’t creep into your home as fast during summer.

What Does Insulation Do?

When insulation is installed in the roof, internal and external walls and floors, it helps regulate temperatures inside your home so that you can stay cooler in summer and warmer in winter. If you’ve noticed that your home fills with hot air quickly on a hot day or is full of cold air on a winter’s day, it could be time to install insulation or upgrade your existing insulation to help you regulate temperatures better.

Understanding Heat Flow

To understand how insulation manages to keep pleasant temperatures inside your home, you first need to understand heat flow.

Heat is thermal energy. It always flows from areas of high thermal energy (hot areas) to areas of low thermal energy (cooler areas) until both areas are equal. So if it’s hot outside, and cooler inside your house, that thermal energy will tend to flow into your house. The same is true if your home is nice and warm and it is cold outside: the heat inside your home will flow outside.

Heat – or thermal energy – can flow via radiation, convection or conduction.

  • Radiation is energy that travels in a straight line from a source such as the sun.
  • Convection is how heat travels through liquids and gases.
  • Conduction is how heat travels through a material from atom to atom.

To prevent warmth escaping from your home in winter, or heat flooding your home in summer, you will need something to resist or restrict heat flow. That’s exactly what insulation does.

How Does Insulation Work?

Insulation materials predominantly help resist radiation and conduction of thermal energy. Below we explain how two main types of home insulation – reflective and bulk insulation – resist heat transfer.

Reflective insulation acts as a radiant barrier. It is made with a thin foil layer on one side. Installing reflective insulation in the roof with the foil layer facing down will help reflect thermal radiation from the sun away from your home.

Bulk insulation works by trapping millions of tiny air pockets which break up the path of heat flow and slow down the conduction of heat into or out of your home. Bulk insulation is commonly made from glasswool (fiberglass insulation) or polyester.

It is critical that bulk insulation is not compressed during installation as this will reduce the number of air pockets and make the insulation less effective. Insulation products with a higher R value have more air pockets, making them more effective at resisting the conduction of thermal energy than those with a lower R value.

What Is The R-value Of Insulation?

In Australia, every insulation product is given an R-Value from R1.0 to R7.0. New homes are required to meet certain R-Value standards, depending on where you live. R-Value is the measure of thermal resistance. Or in other words, the higher the R-Value, the better the insulating material is at resisting the transfer of heat energy. Installing higher R-Values throughout your home will help you keep the indoors at a comfortable temperature year round.

The table below shows our recommended R-Values based on region and where the insulation is being installed. Note, the greatest heat loss and gain occurs in the ceiling. That’s why this area of the home needs a higher R-Value. If your budget allows, upgrading to a higher R-Value will improve the comfort and energy efficiency of your home.


Min. R-Value for Ceiling

Min. R-Value for Walls

Min. R-Value for Floors

Sydney, Melbourne, Adelaide

R5.0 or R6.0



Perth, Brisbane, Northern NSW




For more information, read our guide “What Does R-Value Mean?”.

Installing Thermal Insulation Saves Energy

If high-quality insulation is installed correctly in a home, it will inevitably lead to energy savings. That’s because insulation resists and restricts heat flow, keeping the inside of your home at a more pleasant temperature and reducing the need to use your air conditioner or heater.

For the majority of Australian households, heating and cooling are two of the largest contributors to their power bill. Installing insulation could help reduce these costs significantly.

When you do put the air conditioning on, insulation will help make your cooling more energy efficient. Your air conditioner won’t have to work as hard and the same is true for your heater in winter. Insulation will not only help you save on energy bills, but by reducing your energy consumption, it is one of the best things you can do to make your home more environmentally friendly.

How Does Acoustic Insulation Work?

In this article, we have been talking about thermal insulation and how it resists heat gain and loss. However, there is another type of insulation commonly used in Australian homes called acoustic insulation. Like heat insulation, acoustic insulation provides protection from heat loss and gain, but it also resists the transfer of sound to help keep your home quieter.

When sound waves hit a surface, they are either:

  • transmitted through the material to the other side
  • reflected by the surface and bounced back into the room
  • absorbed by the material

Acoustic insulation is specially manufactured to absorb sound waves and is thicker and more dense than thermal insulation. It is most commonly installed in the internal and external walls and between floors of a multi-storey home to stop sound being transmitted between rooms in the home.

For more information, check out our guide “What is sound insulation and how does it work?”

Choosing The Right Insulation For Your Home

Whether you are looking for roof insulation, underfloor insulation or acoustic wall insulation, choosing the right product for your application is important.

If you are planning a DIY installation, we have many informative articles and guides to ensure you get the best result. Check out our guide on how to install ceiling insulation or watch our DIY insulation videos.

At Pricewise Insulation, we have a wide range of thermal and acoustic insulation options from the most reputed brands in Australia. Buy insulation online today or call us to place an order.

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