Is Styrofoam A Good Insulator: A Comprehensive Guide

With applications in engineering, construction, transportation, and crafting, styrofoam is probably one of the most versatile materials on earth.

But what exactly is styrofoam?
How is it made?
And is styrofoam a good insulator of heat?

To summarise, Styrofoam is made up mostly of air, it is cheap and is very durable all of which make it a great material to use for insulation.

What Is Styrofoam?

When you think of styrofoam you probably imagine the white coffee cups in your workplace or the white structural material used in packaging. While you’re partially correct, this lightweight white material is actually called polystyrene foam.

Styrofoam is actually a specific brand of polystyrene foam manufactured by The Dow Chemical Company. 

The actual Styrofoam brand material is a specific type of extruded polystyrene foam (XPS) which is blue in color, hence the nickname “Blue Board”. It is mainly used in different types of building materials, specifically in pipe insulation or insulation sheathing.

blue board insulation

The white material which is colloquially known as ‘styrofoam’ is actually a different material that is made of expanded polystyrene foam (EPS). 

Polystyrene foam, regardless of the type, is mainly used as an insulation material. The main difference between XPS and EPS is that XPS is a much denser material.

This makes XPS have a higher mechanical and thermal resistance than EPS, which is why it’s preferred in places with extreme weather conditions. On the other hand, EPS is much cheaper which is why it’s also the more commonly seen variant. 

How Does Insulation Work?

Insulation has to do with disrupting the flow of heat and energy.

In simplest terms, it refers to any material that prevents the loss of heat or sound by limiting its ability to transfer from one molecule to another. 

Thermal Insulation

Something gets hot when heat energy is transferred by one of three ways: conduction, convection, or radiation.

Conduction is when heat energy is transferred from molecules colliding with each other, convection refers to heat transferred by the bulk movement of molecules in water or air, and radiation is the emission of energy as electromagnetic waves or subatomic particles which collide with solids. Heat is generally lost upon transfer. 

industrial use styrofoam

Insulation, or keeping something warm, works by stopping the transfer of heat.

This is usually done by introducing a new material into the system that doesn’t conduct heat very well.

This prevents heat from transferring, which also stops heat loss. 

Acoustic Insulation

Sound insulation works much in the same way as thermal insulation. Basically, sound travels through the vibrations of molecules in the air. These molecules, upon vibrating, hit other molecules which then causes those molecules to vibrate as well.

These vibrating molecules eventually reach our ears which then transfer the signals to our brain for interpretation.  

Following the same principle as thermal insulation, acoustic insulation works by introducing a new material into the system that stops the transmission of vibrations. This can be used to keep sound within a room or to keep sound from coming into a room. 

What Makes A Good Insulator?

The quality of an insulator is judged by how well it stops the flow of heat or energy from the source.

This usually depends on the type of material that is used since the material’s structure dictates how well (or in this case, how badly) it can conduct that energy.

For example, solids are a much better conductor of heat (through conduction) than liquids or gas (through convection). This is why good insulators aren’t usually structurally solid.

The most common example where you can see this process in action is in thermal tumblers. These tumblers work by having a layer of air in between the inner layer of metal and the outer layer of metal.

This layer of dry air is not a good conductor of heat and dramatically slows down the transfer of heat from outside the tumbler going inside. Conversely, it can also keep the inside warm for longer periods of time.

Why Is Styrofoam A Good Insulator?

You might be wondering then why styrofoam is used as an insulator when it is a solid material.

foam block installation

This actually has to do with the physical structure of styrofoam. The material itself is made up mostly of air, which does not conduct heat very well. 

Going even further, the styrofoam itself is composed of millions of tiny air bubbles.

Convection works by transferring the heat energy from one solid surface into the air/liquid and then onto another solid surface.

Styrofoam stifles this process by trapping the heat inside those air bubbles, which prevents it from circulating through convection. These properties make styrofoam one of the most popular insulating materials. 

Some Applications Of Styrofoam

Styrofoam (EPS) is very widely used as an insulator thanks to its low price and lightweight-yet-strong structure.

It can be easily shaped and installed into anything that needs insulation, whether that is preventing heat loss from the inside or stopping the heat from entering.

This makes it very popular in any industry that requires any type of temperature regulation. Here are some examples of where styrofoam is used:

  • Household appliances like refrigerators, air conditioners, ovens, or microwaves
  • Soundproofing foam
  • Foodservice packaging to keep food fresh 
  • Construction insulation like in walls, roofs, or floors
  • Has applications in medicine due to its ease of sterilization 
  • Shipment packaging to protect consumer products  

In Conclusion

So is styrofoam a good insulator? The answer is yes, it is a very good insulator with lots of popular applications.

This is because it is made up mostly of air, is cheap, and is very durable. It works as an insulator by trapping heat in its many air bubbles, which prevents it from transferring to other surfaces and mediums through convection.

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My name is Dan and I live very close to an internationally famous stadium which generates an awful lot of noise that I'd rather block out!

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