How Does Insulation Work?

Confused about insulation? We explain how it works to keep your home cool in summer and warm in winter and save you money at the same time.

Using adequate insulation is one of the best ways to create an energy-efficient home. But have you ever wondered how insulation works? What makes it so effective in maintaining a comfortable living environment?

It’s probably not what you think.

In fact, there’s a whole lot of science behind the effectiveness of insulation. And it’s all to do with air!

Air pockets are the key.

When you think of double-glazed windows, what springs to mind?

This very effective building component allows us to see out into the world while helping to keep us insulated from the elements.

They achieve this quite simply by having two panes of glass joined together with a small air space between the panes which is sometimes filled with a special gas to increase the effectiveness of the air. The air effectively slows or prevents the flow of heat.

In summer, double-glazing stops the heat outside from passing through the second pane of glass on the inside while the opposite is true in winter. The warm air inside the house travels through the inner pane and is prevented from going outside by the air that exists between the two panes of glass.

As you can see, even with double glazing, it’s the AIR gap that is actually providing the insulating effect and makes all the difference.

Insulation batts or bulk insulation work in a similar fashion.

The batts that are used inside ceilings and walls operate in a similar way. These are commonly referred to as bulk insulation. These batts consist of fine strands of fibre that trap millions of tiny pockets of air between them.

It’s these air pockets that slow the flow of warm air, keeping the house warmer in winter and cooler in summer. Once again, it’s not the strands of fibre that provide the insulation but rather the small pockets of air that are created by using all of these fine strands that make up the composition of the batts.

Now some people might think that squashing in more batts or using batts that are too large for the available space, will make them more effective. But quite the opposite is true. In other words, cramming a large batt into a small space is not going to have the same effect as using a batt that fits the space perfectly without cramming it in.

You see when you squash the batts, you’re essentially displacing the air that’s held within the fibres. This results in less air within the batts and hence, lower insulating value.

That’s why this type of insulation should really be specified by a professional who understands the science behind it and can also make sure that the batts are installed correctly.

In other words, you want to ensure that you get the right thickness of batts to comfortably fit in the space available. For example, if there’s a 90mm space within the walls, you want to make sure that you use 90mm thick batts so that they fit comfortably within the designated space without being compressed.

The same goes if you have a ceiling space that’s 200mm, you should use batts that are 200mm thick and no thicker.

Reflective insulation.

If you’ve ever seen a new home being built you would have noticed the reflective material that’s wrapped around the frames before the outside cladding is put on. This is commonly referred to as sarking.

This sarking is also used to cover the roof trusses before the metal sheeting or Colorbond is put on.

Because it’s a reflective material, usually made from aluminium foil laminated onto paper, it’s designed to reflect the heat from the outside. In fact, this type of insulation can reflect up to 95% of the radiant heat from the sun.

Reflective insulation can also use air to hinder the flow of heat transfer. Ideally, there should be an air layer of at least 25mm right next to the reflective surface for this to be effective.

What about composite insulation?

By now you’re probably thinking that there’s far more to insulation than you’d ever considered. And you would be right.

Composite insulation uses the combination of bulk materials filled with air pockets in conjunction with reflective materials. For example, you can get foil-backed batts as well as reflective foil blankets that are often used in roof spaces.

The direction of the foil facing will depend on the climate.

Remember that the foil facing is designed to reflect heat. So in cooler climates, the foil would be placed facing inwards to reflect the warm air back into the house.

But in hot and humid climates, the foil would be placed facing outwards to reflect the hot air outside and stop it from entering the home.

This type of insulation material is even more effective in cooler climates when there’s a layer of air between the foil and the plasterboard.

Local climate can also dictate what type of insulation is best.

Different climates will dictate different insulation levels. This ensures that the best insulation is used to make the house as energy efficient as possible.

Luckily, builders of new homes know – or should know – what type of insulation is going to be the most effective and reputable builders will use the right materials that provide the greatest energy efficiency.

The hidden benefit of great insulation.

Did you know that there’s a hidden benefit of having great insulation that will take you one step further to becoming a climate-change warrior?

Not only will proper insulation save you money on your energy bill but it will also significantly reduce your energy consumption. And we all know that using less energy whenever possible is good for the planet and something that we should all be focused on.

By having your home well-insulated, you’ll find that you can turn your heating or cooling on less often. This will immediately reduce your overall energy consumption. Plus once your home is at a comfortable temperature it will take far less energy to keep it that way. Especially if you set your thermostat correctly.

So not only is proper insulation good for your comfort and your back pocket but it also helps you to be more environmentally friendly.

Is it possible to insulate a home incorrectly?

While it’s not all that common, it is possible to insulate a home incorrectly and this can cause other problems as well. As you now know, insulation batts should never be compressed, and you shouldn’t try to cram more in than can properly fit.

Not only does this defeat the purpose of effective insulation but the compression of the air means that moisture can become trapped between the layers of insulation. This lack of adequate airflow can create a problem with mould and stale air within the home.

Plus there have been instances where the over-crammed insulation has even caused the plasterboard to crack and pop out.

Using insulation correctly and having it specified and installed by a professional can reduce your energy costs by up to 45% per year.

So with the rising cost of electricity, this is definitely something you want to concentrate on when building a new home.

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