Installing radiant barriers, factors that impact effectiveness

Heat shield radiant barrier
R+HEATSHIELD radiant barrier can reduce energy costs of a building.

There are several important things commercial and residential building owners can do to reduce energy costs of a building or structure. When insulating a home or adding commercial insulation, it is critical to be sure to install the recommended amount of insulation. In many parts of the U.S., installing a radiant barrier can add significant resistance to the transfer of radiant heat coming from the sun.

A radiant barrier is usually installed on the underside of the roof, to help reduce the flow of radiant heat— the kind of heat transfer that you can feel, such as when the sun shines on your skin. Keeping radiant heat from entering the living space can significantly reduce the air conditioning load of the building as well as improve the comfort of non-conditioned structures.

Factors that impact radiant barrier effectiveness:

  • Climate: Areas that require a lot of cooling will provide the best return on investment
  • Attic insulation: As a general rule, the more insulation in an attic, the less effective a radiant barrier will be
  • Location of ductwork: Radiant barrier systems generate greater savings when HVAC ductwork is located in the attic
  • Installation of the barrier: Radiant barriers are subject to the same guidelines as all building materials – correct installation is required for maximum performance

Radiant barrier material costs tend to be low – around 19 cents per square foot – but installation can add anywhere from 35 cents to $1 per square foot on top of that. Owners should shop around and compare prices and reviews when selecting a contractor to perform the work. Your contractor should be able to supply you with results from tests conducted according to ASTM International that will verify performance of the radiant barrier you’ve selected.

Types of radiant barriers

  • Sheet radiant barrier, the most common type on the market, consists of a low-e, (emissive), highly reflective metalized film, laminated to one or both sides of a substrate that can be of another reinforced film, bubble film or foam. The product is most often stapled to the underside of a roof or across the rafters. Single-sided products should be installed with the reflective surface facing the interior (inside) of the attic. A floor installation requires a perforated product so as to not trap moisture in insulation underneath it. These barriers should only be installed on the floor as a last resort since dust accumulation over time will reduce their effectiveness
  • Interior radiation-control coating systems (IRCCS) are applied as a liquid to the underside of a roof with either a brush or sprayer and are ideal for oddly shaped roofs or attics. Consumers should expect an energy savings of 1 percent to 7 percent. Some IRCCS coatings are designed for exterior walls. While no standard exists for these products, payback will be affected by trees or other features that block the sun’s rays from the side of a home.
  • Reflective insulation consists of a core material with one or more outside layers of low-e metalized film. The core can consist of bubble films, foam or kraft sheets that entrap air spaces. When these products are installed in open applications like an attic, they are considered radiant barriers. When they are installed within cavities with air spaces on one or both sides of the material, they are considered reflective insulations. Reflective insulation products can be used along with other foam and mass type insulation materials to help achieve higher system R-values.

As with many products, independent claims for performance of radiant barriers can be exaggerated and it is important for customers to investigate claims that seem questionable. For radiant barriers and reflective insulation products, a good information resource is the Reflective Insulation Manufacturers International Association – www.rimainternational.org. You can also learn more by visiting our website at www.insul.net, or fill out our Simple Request Form to request a free quote or samples.

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