How Does a Radiant Barrier Work?

A properly installed radiant barrier can boost energy efficiency by reflecting radiant heat for a highly effective insulation solution. Most other insulation neglects heat radiation, operating on heat conduction and convection instead. However, in especially warm and hot climates (like summers in Colorado), it makes all the difference when applied correctly.

What is a Radiant Barrier?

A radiant barrier is a type of insulation that saves savvy homeowners and builders on cooling-system costs by blocking excess heat before it even gets into the house using a reflective surface. This is accomplished with a layer of metallic foil on the surface of specific insulating material.

How Do Radiant Barriers Work?

Radiant barrier insulation is designed to block radiant heat (like the sun’s rays), keeping the other side cool. A common example of radiant heat barriers is windshield sunshades, which keep the automobile’s interior from heating up on hot summer days.

Other types of insulation only block conduction (direct contact) and convection (air-transfer) forms of heat. The sun does not transfer heat merely through the convection of Earth’s atmosphere because solar radiation can travel through the vacuum of space – consider how you feel its warmth on your skin, even on a windless day. Radiant barriers used along with traditional forms of insulation can block all three forms of heat for a full-spectrum method of insulating a structure from excessive heat and saving on heating bills.

A wide variety of structures and spaces are appropriate for radiant barriers, including:

  • Attic space
  • Flooring (including radiant floors)
  • Crawl spaces & basements
  • Roofing
  • Siding
  • Pole barns
  • Tiny homes & yurts
  • Air ducts & other HVAC applications
  • SCIF facilities (for blocking RF frequencies)

Types of Radiant Barriers


With the issue of heat transfer often comes the problem of condensation. To avoid hitting the dew-point temperature, use radiant barriers only in places where the temperature will maintain its warmth. Some fluctuations are inevitable, and perforated radiant barriers are helpful to ensure that moisture can escape. Attics should always have perforated radiant barriers to prevent mould issues.


Since the difference in efficiency between perforated and non-perforated is so small, there are only a few circumstances when non-perforated radiant barrier insulation is preferred. If moisture is consistent (such as under a damp crawl space), a well-sealed and professionally installed non-perforated barrier will ensure that any dampness does not make its way up into the backing insulation material, let alone floor joists.

How are Radiant Barriers Installed?

A radiant barrier requires a layer of “dead” air space on at least one side of the material – otherwise, the physical contact will allow the radiant heat to transfer by way of conduction. For example, think of how hot a single layer of metal gets when heated up, but how a double-layer thermos with a layer of space between them can be held comfortably.

Once installed, the barrier must be kept clean to reflect maximum heat. This is especially important during construction. In our North and Central Colorado projects, we place extra effort towards ensuring that any construction dust is kept off the material to final installation.

Foil-layered radiant insulation can increase conductivity. It’s important to mitigate any risk by ensuring that the structure has adequate electrical ground and lightning rods, especially in high-storm areas.

How Much Do Radiant Barriers Save?

This will vary by structure and climate, and radiant barriers are more effective in hot climates than cool ones. In warm, sunny climates – and the Colorado front range certainly has its share of sunny days – some studies show a reduction in cooling costs of 5–10% with radiant barriers. In the cooler months, the benefits of radiant barriers are lower. As recommended, the need to allocate some space for air pockets could make it less efficient than using more traditional insulation strategies to keep the R-Value at 49 or higher.

Proudly Insulating Colorado Homes

Colorado Insulation & Whole House Fans dutifully serve the Denver Metro, Boulder, Colorado Springs, and Northern Colorado areas. We are experts in radiant barriers and other forms of insulation, as well as whole-house fans and other internal climate controls. Book an appointment or schedule a free, no-obligation home inspection (or over-the-phone estimate) to learn more, and feel free to contact us if you have any questions.