How Does Reflective Insulation Work?

When you’re thinking about insulation options, there are several different methods, and finding the best choice for your application really comes down to understanding how each product works. Whether you’re talking foams, fiberglass, cardboards or shiny bubble wrap, each one works to insulate in a different way. Before we dive into products, lets first address that choosing which insulation is appropriate for you starts by understanding what type of heat transfer you are dealing with.

Okay, I promise not to over-do the science lingo here, but let’s cover how heat transfer works. There are three modes of heat transfer: conduction, convection, and radiation (infra-red). Of the three, radiation is the primary mode; conduction and convection come into play once matter interferes with the radiant heat transfer.

CONDUCTION: Conduction is direct heat flow through matter from actual physical contact. For example, an electric stove uses conduction to transfer heat to a pot resting on the surface, which is also conducted to your fingers when you make contact. The more contact, the greater transfer of heat. This movement of heat is always conducted from the hotter surface to the colder surface, never reverse. Generally, the greater density of an item, the better conductor it is; so inversely, the less dense the mass, the less flow of heat by conduction.

CONVECTION: Convection is the transport of heat within a gas or liquid. Think of a group of people in a tiny room. Their body heat will transfer to the air around them making the room feel hot. These warmed air molecules move in a general upward motion.

How does reflective insulation work?

RADIATION: The last and most prominent mode of heat transfer is radiation. Radiation is the transmission of electromagnetic rays through a space. Like radio waves, waves of radiant heat are invisible, and for this article’s purpose we will be referring to inferred rays only. Mostly everything emits infrared radiation, sending rays from their surface in every direction until they are absorbed or reflected by another surface. These rays have no temperature, only energy. When the rays strike another object, the rays are absorbed and only then do they create heat. The heat then transfers through the object by conduction and then new rays are emitted out of that object.

The amount of radiation emitted is a function of the emissivity (or rate at which radiation is given off) of the source’s surface. So, in plain english, an object (or surface) with low emissivity absorbs little rays, but rather has high reflectivity. Insulation layered with metalized film, like our Astro-sheild, has a low emissivity of 5%. This means it is reflecting approximately 95% of the rays that strike it. This high reflectivity is greatly reducing radiant heat from being transferred into the surface, intern working as effective insulation.

TRY THIS EXPERIMENT: Hold a piece of Astro-sheild reflective insulation close to your face without touching the surfaces. You will begin to feel the warmth of your own infrared rays being reflected back towards your face and being absorbed by your skin surface. While your skin and the insulation are both solid surfaces, the insulation has a low emissivity (5%) and your skin has an emissivity of 99%, so the rays are being absorbed by your skin and heat is conducting throughout the surface.

You can imagine how the same principles would apply as this effective insulation is implemented in a building or packaging application to help keep heat transfer to a minimum, and keep your space in a desired temperature range.

*Do you have a building that you’d like to keep cooler in the summer and warmer in the winter? Call us about using reflective insulation. 800-776-3645 or

*Do you have temperature-sensitive goods you’re worried about shipping? Call or email us about using InsulTote packaging to keep your goods safe during transit. 800-776-3645 or