Radiant Barrier vs Insulation: What’s the Difference?

When we think about protecting our homes from the elements, our thoughts tend to go towards insulation against the cold. Anyone with a drafty window in the middle of winter can appreciate the value of a tightly sealed home. 

But did you know that there are ways you can also keep your house cooler in the summer?

Radiant barriers can be installed alongside insulation in the attic space, providing a heat shield that can lower cooling costs in the summer months. Today, you’ll learn about the benefits of radiant barriers and insulation, and how both can reduce heating and energy costs!

Radiant Barriers Are Not The Same As Insulation

When weatherizing a home, the primary objective is to make it as comfortable as possible throughout the four seasons. Aside from central heating and cooling, there are two different kinds of building materials commonly used to perform this task: insulation and radiant barriers.

While both perform the same function—keeping your home at a reasonable temperature—the ways this is done vary greatly between the two. 

This is because heat does not spread in a uniform way.

  • Insulation blocks conductive heat – Insulation is like a down coat for your home. By providing a thick layer of insulation material, heat is slowed down and penetrates through your walls more slowly. The higher the value of resistance, or R-value, the slower it enters your home.
  • Radiant barriers block radiant heat – Park your car outside for a few hours on a hot summer day, and you’ll return to a furnace. Radiant barriers bounce the rays of the sun back from where they came from, even when installed underneath roofing. Rather than slowing heat, they prevent it from entering your home. On average, radiant barriers reflect around 95% of radiant heat.

Radiant heat is the single greatest source of heat accumulation in a home, while conductivity causes the greatest amount of heat loss. Yet between the two, most homeowners opt for insulation rather than radiant barriers. 

Why is this the case?

On average, Americans spend more on their heating costs than they do on their cooling costs. This has a lot to do with regionality. Energy bills in the United States vary greatly from one end to the other, but residents of San Diego and Orange County are far more likely to have high air conditioning costs than a resident of North Dakota.

Radiant Barriers and Insulation Control Heat in Both Directions

While insulation is most commonly associated with winter and radiant barriers with the summer, it is incorrect to assume that they don’t function outside of their seasons.

After finishing a marathon, racers are often covered in a reflective surface or blanket. This isn’t to protect them from the heat, but to raise their core temperature. After extreme exercise, the body releases heat faster than it can retain it, which can lead to shock. This blanket reflects the heat back in.

Much in the same way, homes in the Midwest can cover the joists of their attic floor with reflective barriers to keep radiant heat from exiting through the roof during the cold winter months. This means radiant barriers serve a dual purpose—keeping the summers cool and the winters warm.

By slowing heat, insulation helps keep the air conditioning unit running less in the summer, but it will also keep heat trapped in your home longer without it. This is why in warmer climates, a mixture of both insulation and radiant barriers tends to produce the greatest value.

Radiant Barrier vs Insulation: Which Do I Need?

Deciding on whether you should install a radiant barrier or insulation is not a zero-sum game.

Radiant barriers aren’t required in colder states, and even in the hottest states aren’t found in every home. However, they provide significant benefits in terms of energy savings and comfort levels to those that do. Virtually all residents of California will benefit from installing radiant barriers in their attic space.

Insulation is recommended for all homes, although how much is needed varies from location to location. The Department of Energy has split the U.S. into seven zones as a guideline for how much insulation is necessary for your attic. The amount of insulation is referred to as an “R-value.” For Californians, it is recommended that they meet attic insulation levels of R-30.

Your home should meet the minimum insulation requirements to keep bills low. 

To determine whether you need an attic radiant barrier, ask yourselves these questions:

  • Am I paying too much for my electric bill in the summer?
  • Do the rooms directly beneath the attic tend to get hotter during the day?
  • Does my home receive direct sunlight throughout most of the year?

If you answered yes to any of these questions, an attic radiant barrier may be the solution to your cooling needs.

Radiant Barriers and Insulation Are Good For The Environment

Most homes in the United States have insulation, and many homes do not have radiant barriers. But over the past few years, this statistic has begun to change. As Americans are becoming more conscious of how their energy usage contributes to climate change, many have begun installing radiant barriers or better insulation to decrease their carbon footprint.

In 2009, air conditioning constituted around 6% of all residential energy usage. 

This adds up to about 100 million tons of carbon dioxide released into the atmosphere every year. Since then, that number has only gone up. Heating costs constitute an even greater percentage of energy spent, and both are largely fueled by burning coal.

Since these pronouncements, some homeowners have gone out of their way to make their homes as carbon efficient as possible. To this end, many start by looking at ways to decrease their heating and cooling costs. For those looking to save the environment, residents of colder states tend to install radiant barriers even though they do not produce the same cost savings.

The Bottom Line: the Value of Radiant Barriers and Insulation

While some people use radiant barriers and insulation to control the temperatures of their home for comfort, and others for environmental reasons, others are more concerned about the bottom line. How much money can you expect to save by installing radiant barriers or better insulation?

Besides your region, there are several factors that play into this. On average, radiant barriers have been shown to decrease cooling costs by around 10%. Homes with these features are likely to see the greatest savings after installing radiant barriers:

  • Ductwork/HVAC Equipment in Attic – Older homes are more likely to store air conditioning equipment in the attic. This is an energy efficiency nightmare. Because attics are typically the hottest parts of your home, your air conditioning units will have to work harder to keep your home cool, increasing energy expenditure and maintenance costs. Radiant barriers will dramatically decrease power consumption in these homes.
  • Unsuitable HVAC Units – As technology progresses, the tools we use can do more while spending less energy. Homes with radiant barriers use less energy on cooling, meaning that some homeowners are able to switch to smaller air conditioning units. These units break down less often and require less energy to provide the same cooling benefits.
  • No Trees Around Home – As mentioned before, homes that receive the most sunlight throughout the course of a year tend to be the hottest. A home without trees to provide shade will save more by installing radiant barriers.

All homes should meet the recommended R-value guidelines for insulation based on their region. Because heating bills tend to be higher than cooling costs, a poorly insulated home can siphon away your money even in hotter climates. 

Remember that insulation slows heat transfer—even in the summer months, insulation paired with air conditioning works in your favor.

Do Insulation and Radiant Barriers Become Less Effective Over Time?

Properly installed insulation tends to last anywhere around 80 to 100 years. Radiant barriers last even longer. While insulation material such as polystyrene and polyurethane tend to become slightly less efficient over time, the age of your insulation is probably not responsible for high costs (barring homes made before 1940). 

More than likely, your insulation was never sufficient in the first place.

Heating and cooling account for 50%-70% of any home’s energy bills. For homes ill-equipped for the elements, these costs can be even higher. While older homes are most often the culprits for unnecessary energy expenditure, most homes built today still do not meet the optimal requirements for insulation and radiant barrier protection.

Insulation and Radiant Barrier Installation Services

Without being an expert in the field, it can be difficult to know whether your home is as energy efficient as it could be. One easy way to know if you can be saving money is by entering your attic and surveying the area. If you have an HVAC unit without radiant barriers, or you can identify missing insulation coverage near the joists, you could be saving more money on your electric bill.

Unsure if radiant barrier or insulation installation is the right move for your attic? Attic Construction offers a free attic inspection and estimate with zero strings attached. We will survey your attic, remove old insulation, seal up your attic, and install new insulation or radiant barriers, all with a $300 discounted rate for San Diego residents.

Attic Construction is the #1 attic restoration company in San Diego, CA. Since 2011, we have prided ourselves on providing the best service in the industry. We also offer Orange County and Phoenix insulation installation, you can count on us for the best insulation service. Give us a call today!


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