Reflective insulation is a type of insulation that helps keep your home warm in the winter and cool in the summer. It can be installed in attics, ceilings, and floors, and is available as either a sheet or a spray.
While reflective insulation offers a number of benefits, there are also some factors to consider before making a decision about whether this type of insulation is right for your house, including climate, humidity, and longevity.
In this blog post, we will take a look at the pros and cons of reflective insulation so that you can make an informed decision about whether it is right for you.
What Is Reflective Insulation?
Reflective insulation is a type of heat protection system designed to cool down a space by blocking and reducing the sun’s radiant energy. It is made with reflective surfaces—usually in the form of aluminum foil—and comes with an air cushion in between which is available in different materials, including plastic film, kraft paper, polyethylene bubbles, and cardboard.
Reflective insulation is typically composed of two layers of aluminum foil, while the standard thickness of the cushion is 1/4 inches. Reflective insulation products are available with either a single layer or double layer of air bubble wrap, too.
Designed to block radiant heat energy, reflective insulation is commonly applied in strategic locations such as the attic, where the sun’s radiant energy directly hits the roof. It is also used in houses located in areas with high temperatures. It is also more efficient to use in areas with high temperatures compared to places with colder weather. It is also effective in houses with asphalt roofing (which absorbs sunlight easily) or those with little to no shading.
Reflective insulation also helps you keep the house warmer in the winter by reflecting heat radiant energy that tries to escape your house through the attic and ceiling.
Below is a chart showing the properties and the R-Values of reflective insulation products.
|Property||Single Layer Air Bubble Wrap||Double Layer Air Bubble Wrap|
|Reflectivity||0.96 to 0.97||0.96 to 0.97|
|Fire Rating||Class 1 and Class A||Class 1 and Class A|
|Permeability||Zero for foil||Zero for foil|
|Temperature Exposure||-60F to -180F||-60F to -180F|
|Emissivity||0.03 to 0.04||0.03 to 0.04|
|Weight (per sq. ft.)||0.8 oz||1.25 oz|
|Puncture Resistances||63 psi||66 psi|
How Does Reflective Insulation Work?
Reflective insulation works differently compared to other types of insulation. It is because while heat protection systems like mineral wool and fiberglass reduce heat by slowing down convective and conductive heat flow, a reflective system is designed to lessen the radiant heat gain that the sun emits.
Without it, the radiant energy the sun emits moves through the roof’s underside and to the cooler areas in the attic. Hence, the reflective system works by reflecting sunlight and, as a result, lessens the amount of radiant heat transferred from the roofing’s underside to other cooler areas in the attic.
Does Reflective Insulation Have an R-Value?
You might be wondering whether reflective insulation has an R-Value given that it resists heat differently compared to other insulation materials. To answer the question, reflective insulation has an R-Value. However, it varies and is influenced by several factors.
Per the paper published by Oak Ridge National Library, reflective insulation has a ‘system R-Value’ rather than a ‘material R-Value.’ It means that its measured thermal performance is largely determined by the heat flow’s direction, as well as the changing temperature across the assembly.
That said, reflective insulation must have high reflectance of 0.9 or above and a low emittance of 0.1 or less to achieve at least an R-Value of 1. Regardless of these factors, such a material has an R-Value that ranges between R-13 and R-17.
But do take note that reflective insulation’s emissivity can change over time, specifically due to corrosion. Heat and humidity cause aluminum to erode.
Where Is Reflective Insulation Commonly Used?
When it comes to application, reflective insulation is used in the same type of buildings that use mass insulation to absorb, store, and release heat. It is, however, usually applied in areas where the sun’s radiant energy directly hits, primarily the attic and ceiling.
A reflective system is also installed in areas such as wall cavities as well as between floor and ceiling joists as radiant energy and convective heat barriers. It can also be integrated into the roofing system and is typically placed in either the air gaps made by paneling interior masonry walls, between the rafters and decking or between tiny air gaps between roofing and decking.
Aside from that, it is suitable in areas that can accommodate neither batt and rolls nor loose-fill types of insulations.
Is Reflective Insulation the Same as Radiant Barrier?
While virtually similar in function, reflective insulation and radiant barrier are two different insulation materials. Although a lot of homeowners, and even professional builders, use the term interchangeably.
Having said that, the two differ primarily in physical composition as well as in R-Value. In terms of R-Value, a reflective barrier has none.
A radiant barrier is a single sheet of reflective foil by definition and is usually applied in strategic locations to lessen unwanted heat gain or heat loss. Reflective insulation, on the other hand, is composed of two or more layers of reflective materials. It contains an air cushion that is placed in between as well.
How Does Reflective Insulation Compare to Other Types of Insulation?
|Insulation Material||R-Value per inch|
|Reflective Insulation||R-3 to R-17|
|Batts and Rolls Fiberglass||3.1 to 3.4|
|Blown-in Fiberglass||2.2 to 4.3 (attic) /3.7 to 4.3 (wall)|
|Batts and Rolls Mineral Wool||3.1 to 3.4|
|Blown-in Mineral Wool||3.1 to 4.0 (attic) / 3.1 to 4.0 (wall)|
|Open Cell Spray Foam||3.5 to 3.6|
|Closed Cell Spray Foam||6.0 to 6.5|
|Polyurethane Board||5.5 to 6.5|
|Polystyrene Board||3.8 to 5.8|
|Blown-in Cellulose||3.2 to 3.7 (attic) / 3.8 to 3.9 (wall)|
Reflective Insulation vs Batts and Rolls Fiberglass
While both virtually share the same function, reflective and fiberglass insulation are two distinct materials. In fact, from how they resist heat to where they are commonly applied, these two materials vary to a great degree.
Here’s a quick comparison list:
- Heat flow resistance. A reflective insulation system works by blocking and resisting radiant heat that the sun emits, while batts and rolls resist heat convective and conductive heat flow.
- R-Value. In terms of measured thermal performance, reflective insulation provides system R-Value while batts and rolls provide material R-Value. That said, reflective insulation’s R-Value ranges between R-3 to R-17, while batts and rolls have an R-Value of 2.9 to 3.8 per inch.
- Application. Batts and rolls are typically installed in floor attic and crawl spaces. Reflective insulation, on the other hand, is usually installed on the roof and other strategic locations where radiant heat can escape to.
- Composition. Both types of insulation differ also when it comes to their forms. The reflective system is made with reflective surfaces using aluminum foil and comes with an air cushion—which can be in the form of kraft paper, plastic film, cardboard, and polyethene bubbles.
Batts and rolls, on the other hand, are typically available with or without facings and are made of fibrous materials such as fiberglass, mineral wool, and plastic fibers.
Reflective Insulation vs. Spray Foam
Just like batts and rolls, the difference between reflective insulation and spray foam is also huge. Here’s a quick list of how they differ:
- Heat flow resistance. If there is one similar factor that reflective and spray foam insulation have, it is that they both can resist radiant heat gain. Still, spray foam gets the upper hand as it can also block conductive and convective heat transfer.
Spray foam is also known as an excellent material to block air movement and avoid air leakage within the assembly.
- Application. Spray foam and reflective insulation materials greatly vary when it comes to application and installation. It is because spray foam is typically used to seal new and old cavities in walls, floors, and attics. It is installed via spray containers or poured using a slow-curing liquid foam.
A reflective insulation system, however, is typically installed on the roof and other strategic locations where radiant heat can escape to.
- R-Value. Spray foam insulation gets the upper hand in terms of thermal performance. It is because—depending on the type of spray foam insulation—its R-Value can reach up to 6.5 per inch. Take note as well that spray foam can resist all three types of heat flow, which can essentially provide more comfort compared to reflective insulation alone.
- Composition. Both materials greatly differ in terms of composition too. Reflective insulation is made with aluminum surfaces and has an air cushion in between, which is typically made of cardboard, kraft paper, or bubble wrap. However, spray foam is commonly made of polyurethane.
Reflective Insulation vs. Loose Fill
- Heat flow resistance. Loose-fill or blown-in insulation resists heat flow the same way as batts and rolls. It blocks conductive and convective heat transfer, while reflective insulation can only resist radiant heat.
- Application. Blown-in insulation is commonly applied in attics and crawl spaces. It is also efficient to use on walls. Reflective insulation, on the other hand, is usually installed on the roof, unfinished ceilings, and floors.
- R-Value. Reflective insulation’s R-Value ranges between R-3 to R-17. Loose fill, on the other hand, ranges between 2.2 and 3.8 per inch, depending on the material used.
- Composition. Reflective insulation is made of reflective surfaces with an air cushion in between, while blown-in can be either in the form of fiberglass, cellulose, or mineral wool.
Perks and Drawbacks of Reflective Insulation
Now that you know what reflective insulation is, let’s talk about its perks as well as its disadvantages.
Pros of Reflective Insulation
Highly Effective In Warmer Climates
Because reflective insulation is designed to resist the radiant energy gain that the sun emits, it is naturally efficient to use in houses located in areas with warm climates. The Department of Energy guarantees that it can help save up to 10% of energy costs if used in sunny and hot climates. It also helps your HVAC system to work efficiently and keep your home cool even during summer’s high temperature.
It Is Extremely Versatile
Reflective insulation is also flexible in terms of usage and applications. Because aside from wall cavities and ceiling joists, builders also integrate them into the roofing system. It can be applied in areas that batts and rolls and even loose-fill insulation cannot reach.
Highly resistant to molds and does not degrade easily
Lastly, reflective insulation does not degrade easily. Unlike cellulose and fiberglass, it is not prone to mold and mildew and highly resistant to moisture.
Cons of Reflective Insulation
Not efficient to use in houses or buildings in cold climates
Since it is designed to resist and, accordingly, reduce the radiant heat gain that the sun emits, using reflective materials as an insulation system in houses or buildings located in areas with cold weather is not as efficient as those in hotter climates.
Professionals suggest using it alongside thermal insulation. But using two systems rather than one would cost you more money. Hence, it is not cost-effective in places with colder weather.
Low R-Value Permanence
While it is an efficient insulation material for areas with hot weather, some studies found reflective materials to have poor R-value permanence. According to a report conducted by the Oak Ridge National Laboratory, the ability of reflective insulation to reduce radiant heat energy does not last long. Subsequent studies are limited and contradictory as well.
Emissivity, for example, can significantly affect the material’s R-Value. As mentioned, a reflective system requires low emittance surfaces to efficiently work. An increase in surface emittance due to any processes is found to have a significant influence by lowering the material’s R-Value.
It can pose an electrical hazard
Aluminum is innately a good electrical conductor. For that reason, many industry competitors claim that reflective insulation must be handled with caution as it can cause an electrical hazard. Manufacturers, on the other hand, refute such claims and say that such situations are non-existent.
Position and installation affect its ability to resist heat flow
The study conducted by ORNL also shows that factors such as the position as well as the installation can greatly affect the material’s R-Value. Based on the examination using a one-dimensional model developed specifically for the analysis, reflective insulation’s ability to resist heat flow is dependent on how it is positioned. Hence, also the installation.
Poor spacing is the primary concern. Although, there were no found insights into whether missing sections, gaps, and tears can affect the R-Value.
Prone to dust and dirt
Lastly, reflective insulation is prone to dirt and dust. While these are harmless and may not affect the material physically, dust and dirt can reduce its thermal resistance efficiency.