To understand what a radiant barrier is and how reflective insulation can help lower home energy bills, one should understand the concepts of heat transfer by conduction, convection and radiation.
Conductive heat transfer takes place through a solid substance by transfer of the kinetic energy between individual atoms. This kinetic or heat energy can be transferred directly between substances only through physical contact. People are most aware of this form of heat transfer by touching a hot pan.
Convection is the movement of heat through liquids and gases and involves the actual movement of atoms. Heat transfer can occur through “natural” convection or can be “forced” by a fan or pump. Both conductive and convective energy transfer occurs from a high temperature region to a lower temperature region or from hot to cold.
Radiant heat is electromagnetic waves similar to visible light that can pass through fluid, gas or a vacuum. However, to differentiate it from the sun’s radiant energy, radiant heat is associated with the invisible infrared frequencies that radiate from any substance.
Following the same physical laws as light, radiant energy is unaffected by thermal currents or convection. Additionally, thermal radiation may pass through an infrared transparent substance. Consequently, any medium that is less than 100% transparent is a radiant barrier. However, a radiant energy barrier is not a conduction energy barrier. For example, a reflective metal is an excellent heat conductor.
Houses form a thermal island that, for comfort, is most often maintained out of equilibrium with its surroundings by heating and/or cooling systems. To lower energy costs, insulating materials help maintain disequilibrium by keeping heat in or out.
Thermal insulators are designed to limit conduction, convection or both to reduce the flow of heat from a home’s interior space. Most people are aware of the use of R-values as a measure of insulating properties for thermal insulation. R-values increase with layer thickness and decrease with a lower convection coefficient.
Radiant barriers are materials used to reduce the flow of heat from radiant heat sources. Radiant barrier comparisons are based on reflectivity. Total or 100% refection of radiant energy equals a reflectivity of 1. Emissivity is a measure of the radiation energy passed through, and is 1 - reflectivity. Values are wavelength dependent. Bright materials have high reflectivity, and dark materials have high emissivity.
In warm climates, reflective insulation is commonly installed in a homes attic to reduce cooling costs by blocking radiant heat gain. For air-conditioned homes, particularly when cooling ducts are present in the attic, reflective insulation can reduce cooling costs substantially. Because most reflective insulation serves as an excellent heat conductor, an air space (3” - 5”) must exist between the radiant barrier and the radiant heat source - the roof’s interior surface.
Most reflective insulation consists of “thick” aluminum foil applied to one or both sides of a rigid substrate that provides stability, durability and ease of installation. However, a radiant barrier does serve to reflect emitted radiation from objects in the home. Consequently, in cooler climates, a radiant barrier facing on thermal insulation provides both thermal and reflective insulation.
Friday, September 28, 2012
Tuesday, October 7, 2008
Good article about history of Rima
RIMA International - Celebrating 30 Years and Growing
The Reflective Insulation Manufacturers Association International (RIMA-I) celebrates 30 years of service to the reflective insulation, radiant barrier and interior radiation control coatings industries this year. The association was founded in 1978 by a small group of industry professionals interested in educating building professionals and consumers on the benefits and uses of reflective products.
They also took an active role in the American Society of Testing Materials International (ASTM) by helping write the testing and installation standards for reflective insulation and radiant barriers which continues still today.
One of the association’s first accomplishments was participating in the DOE/FTC 1979 hearings in Washington, DC, that addressed insulation products. At the completion of the hearings, the Federal Trade Commission published what became known as the "R-Value Rule". This rule still governs the way all insulation products and radiant barriers are packaged, tested, and sold today.
In the second half of the 1980's RIMA-I’s efforts helped reflectives make a significant contribution to energy conservation. The process continues at an aggressive pace with efforts directed to gaining greater presence in the marketplace for all reflective products. This is reflected in the recent Freedonia Study which states that reflective insulation and radiant barriers will see the fastest growth over the next five years with a projected 11.4 percent
increase from 2007-2012 – 5.5 percent more than any other insulating material.
Reflectives lead the pack over the previous five years as well with an 11.5 percent growth from 2002-2007 – 6.9 percent higher than the rest.
One campaign contributing to this growth is the association’s Radiant Barrier Software Task Group which is working to establish uniform calculations among various tax credit software programs when a radiant barrier is added to a building.
The association recently changed its name to RIMA International and has expanded involvement from North American into European countries. Twelve countries make up the current membership, and RIMA-I will continue to evolve to serve the industry on a global level.
The association held its first international meeting in April 2007 in Paris, France, and will hold their next in Barcelona, Spain, in May 2009.
RIMA continues to work with many of the organizations, societies, associations, and governmental agencies to gain further acceptance of these products and help establish standards that promote their best use.
The association will be launching a new Verification Program for 2009 which will verify test data for member companies, which in turn will provide the consumer a reliable resource for verifying product performance claims.
RIMA International has made a tremendous impact in advancing the reflective insulation, radiant barrier and interior radiation control coating industries over the last 30 years, and they will continue into the future through the hard work and dedication of their membership and their commitment to a more energy-efficient world.
As the tag line
states, “It’s About Saving Energy”.
The Reflective Insulation Manufacturer's Association International is a group of dedicated people working together to propagate the knowledge and use of reflective insulations and radiant barriers. RIMA-I has been the major force in establishing fair ASTM standards for testing and installation procedures. RIMA-I welcomes all who are interested in promoting and directing the growth of the industry.
For more information about membership or the industry, please contact Executive Director Mary Edmondson at
800/279-4123.
The Reflective Insulation Manufacturers Association International (RIMA-I) celebrates 30 years of service to the reflective insulation, radiant barrier and interior radiation control coatings industries this year. The association was founded in 1978 by a small group of industry professionals interested in educating building professionals and consumers on the benefits and uses of reflective products.
They also took an active role in the American Society of Testing Materials International (ASTM) by helping write the testing and installation standards for reflective insulation and radiant barriers which continues still today.
One of the association’s first accomplishments was participating in the DOE/FTC 1979 hearings in Washington, DC, that addressed insulation products. At the completion of the hearings, the Federal Trade Commission published what became known as the "R-Value Rule". This rule still governs the way all insulation products and radiant barriers are packaged, tested, and sold today.
In the second half of the 1980's RIMA-I’s efforts helped reflectives make a significant contribution to energy conservation. The process continues at an aggressive pace with efforts directed to gaining greater presence in the marketplace for all reflective products. This is reflected in the recent Freedonia Study which states that reflective insulation and radiant barriers will see the fastest growth over the next five years with a projected 11.4 percent
increase from 2007-2012 – 5.5 percent more than any other insulating material.
Reflectives lead the pack over the previous five years as well with an 11.5 percent growth from 2002-2007 – 6.9 percent higher than the rest.
One campaign contributing to this growth is the association’s Radiant Barrier Software Task Group which is working to establish uniform calculations among various tax credit software programs when a radiant barrier is added to a building.
The association recently changed its name to RIMA International and has expanded involvement from North American into European countries. Twelve countries make up the current membership, and RIMA-I will continue to evolve to serve the industry on a global level.
The association held its first international meeting in April 2007 in Paris, France, and will hold their next in Barcelona, Spain, in May 2009.
RIMA continues to work with many of the organizations, societies, associations, and governmental agencies to gain further acceptance of these products and help establish standards that promote their best use.
The association will be launching a new Verification Program for 2009 which will verify test data for member companies, which in turn will provide the consumer a reliable resource for verifying product performance claims.
RIMA International has made a tremendous impact in advancing the reflective insulation, radiant barrier and interior radiation control coating industries over the last 30 years, and they will continue into the future through the hard work and dedication of their membership and their commitment to a more energy-efficient world.
As the tag line
states, “It’s About Saving Energy”.
The Reflective Insulation Manufacturer's Association International is a group of dedicated people working together to propagate the knowledge and use of reflective insulations and radiant barriers. RIMA-I has been the major force in establishing fair ASTM standards for testing and installation procedures. RIMA-I welcomes all who are interested in promoting and directing the growth of the industry.
For more information about membership or the industry, please contact Executive Director Mary Edmondson at
800/279-4123.
www.rima.net
This site is the governing body of the radiant barrier, reflective foil industry. Definately worth checking out.
www.insulationstop.com
Check this out, a fantastic resource for radiant barrier, reflective foil insulation products. Site includes products used for pole barns, under slab projects, ductwork projects, and etc. A great resource on reflective foil insulation.
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