Professional Installation
The installers were very professional and did an excellent job on the installation.
Advanced Radiant Barriers
Reduce Heat & Save Energy
About Radiant Barriers
California Doors and Windows Radiant Barriers are a specialized type of thermal insulation material that inhibits heat transfer by thermal radiation. They reflect the heat rather than absorbing it or letting it pass through. Since Radiant Barriers are used in reducing downward heat flow, they are great for attics, ceilings and roofs in hot climates.
Unlike Batt/Mass/Bulk Insulation, Radiant Barriers are a reflective type of insulation which blocks and reflects heat energy in the form of radiation due to a low emittance surface, preventing radiant heat from transferring from one side to the other side.
Heat/thermal insulation is a barrier material which resists, blocks or reflects heat energy (conduction, convection or radiation) to prevent its transfer through the boundary between two systems which are at different temperatures. Heat transfer always occurs from a region of higher temperature to one of lower temperature.
How Radiant Barriers Work
Emissivity & Reflectivity
All materials give off energy by thermal radiation as a result of their temperature. Emissivity (expressed 0-1) is the amount of energy radiated. Reflectivity measures how much energy is reflected. These values sum to 1 by Kirchhoff's law.
Visual vs. Thermal Properties
Radiant barriers may appear visually dark but have low thermal emissivity. Reflectivity at visible wavelengths and emissivity at thermal wavelengths do not necessarily sum to 1, allowing for dark colored surfaces with low thermal emissivity.
Air Space Requirement
To perform properly, radiant barriers need to face open space (air or vacuum) through which radiation can occur. Without adequate air space, effectiveness is severely compromised.
High Reflectivity
Radiant barriers used in attics and roofs have low emissivity and high reflectivity to reflect radiant heat. They must face towards the hottest side of the area that needs protection.
The History of Radiant Barriers
In 1860, French scientist Jean Claude Eugene Peclet experimented with the insulating effects of high and low emissive metals such as tin, cast iron and steel facing air spaces. Peclet concluded that neither visual reflectance nor the colors of the material were significant factors in performance. He calculated the reduction in BTUs for high and low emissive surfaces, discovering the benefits of radiant barriers in reducing heat transfer.
In 1925, German businessmen Schmidt and Dykerhoff filed for patents on reflective surfaces for building insulation. Improvements in technology allowed low emissivity aluminum foil to be commercially viable, launching radiant barrier and reflective insulation around the world. Within 15 years, millions of square feet were installed in the US alone. Within 30 years, radiant barrier was included in projects at MIT, Princeton, and Frank Sinatra's residence in Palm Springs, California.
For the Apollo program, NASA helped develop a thin aluminum metalized film that reflected 95% of radiant heat, protecting spacecraft and astronauts from thermal radiation. Radiant barrier was inducted into the Space Technology Hall of Fame in 1996 as a Space Foundation Certified Space Technology.
Applications & Uses
Roofs & Attics
When roofing materials get hot, they radiate heat downward toward the attic floor. Radiant barriers reflect this heat back toward the roof, reducing heat transfer to insulation and rooms below, saving money on cooling bills.
Window Treatments
Windows can be coated with low-e films using a sputtering process where aluminum is vaporized onto polyester. These thin coatings allow visible light through while resisting radiant heat transfer. Homeowner-applied films typically last 10-15 years.
Walls
Radiant barrier can be used as a vented skin around exterior walls with furring strips creating air space between barrier and siding. Wrapping a house with radiant barrier can result in 10% to 20% reduction in air conditioning system requirement.
Floors & Textiles
Reflective foil and bubble foil insulations are noted for reflecting unwanted solar radiation in hot climates. Since the 1970s, space blankets (metalized polyester sheets) have been used to prevent hypothermia in survival and first aid applications.
Installation Methods
There are several methods for installing radiant barriers, each with specific advantages:
Over Roof Sheathing
For metal or tile roofs, radiant barrier is applied directly over roof sheathing with furring strips (1x4s) applied over the barrier before the roof is installed, ensuring sufficient air space.
Draped Installation
Radiant barrier sheets are draped over framing timbers (trusses or rafters) and under roof decking, creating a small air space above with the barrier facing into the interior attic space below.
Pre-Laminated Panels
Pre-laminated OSB panels or roof sheathing combine radiant barrier with roof decking in one product, reducing labor costs in new construction projects.
Stapled to Rafters
For existing attics, radiant barrier may be stapled to the underside of roof rafters, providing dual air spaces. Vents must remain open to prevent moisture buildup in the attic.
Over Attic Insulation
Laying radiant barrier over top of attic floor insulation can be more effective in winter. Breathable barriers with perforations (minimum 5 perms) are required to allow moisture transmission.
Energy Savings & Benefits
According to a 2010 study by the Building Envelope Research Program of the Oak Ridge National Laboratory, homes with air-conditioning duct work in the attic in the hottest climate zones, such as the US Deep South, could benefit the most from radiant barrier interventions, with annual utility bill savings up to $150.
Homes in milder climates, such as Baltimore, could see savings about half those of their southern neighbors. If there are no ducts or air handlers in the attic, annual savings could range from about $12 in Miami to $5 in Baltimore. Nevertheless, a radiant barrier may still help improve comfort and reduce peak air-conditioning loads.
Studies show that radiant barriers can reduce cooling costs 5% to 10% when used in warm, sunny climates. The reduced heat gain may even allow for a smaller air conditioning system. In cool climates, however, it's usually more cost-effective to install additional thermal insulation than to add a radiant barrier.
Common Misconceptions
Shingle Temperature Damage
A common misconception is that heat reflecting off radiant barriers back to the roof increases roof temperature and damages shingles. A Performance test by the Florida Solar Energy Center showed temperature increase during the hottest part of the day was no more than about 5°F. Large roofing manufacturers confirm radiant barriers do not affect shingle warranties.
Dust Accumulation
When radiant barrier is installed over attic insulation, dust accumulation may occur. While a TVA study found minimal effects from small dust amounts, heavy accumulation could reduce reflectivity. Proper installation methods and air space management help minimize this concern.
Climate Limitations
Radiant barriers are more effective in hot climates than cool climates. The American Department of Energy and Ministry of Natural Resources state these systems are not recommended for cold or very cold climates where standard insulation is more cost-effective.
Climate Considerations
A Radiant Barrier is significantly more effective in hot climates like Texas than in cooler climates like New York. When solar energy heats a roof, much of the heat travels by conduction through roofing materials to the attic. The hot roof then radiates heat onto cooler attic surfaces. A radiant barrier reduces this solar heat transfer to attic surfaces.
Even though California has a moderate climate compared to states like Texas, Florida and Louisiana, energy costs money. Stop giving your hard-earned money to utility companies. You would be smarter and better off calling California Doors and Windows to receive a Free Home Energy Evaluation for your home.
Is Your Home Getting Too Hot?
Let our experts evaluate your home's energy efficiency and recommend the best radiant barrier solution for your climate