Thermal Performance: Beyond R-Value
R-value is a measure of the ability of insulation materials to resist heat transfer. The higher the
R-value, the greater the insulating value. R-value is a very accurate, and reliable expression of
how insulation materials perform in a laboratory apparatus. In the real world of buildings, thermal
performance is a lot more complicated and R-value is only one of many factors in the actual
performance. These factors include total R-value of all system components, air infiltration due to
leakage through gaps in the system, air infiltration due to permeability of system materials,
convective flow within insulated systems, thermal bridging across the building envelope, and the
thermal mass of building components.
So how does one evaluate this?
Wouldn't it be reasonable to simulate conditions closer to the structures we live in. Read on and
find out what researchers discovered when this was done.
Two independent studies by the University of Illinois and Oak Ridge National Laboratory documented
the long standing claim that cellulose insulation outperforms loose-fill fiberglass insulation
because of it's higher density and lower air permeability.
These tests studied a range of cold attic temperature conditions rather than a single laboratory
condition. At attic temperatures of 30°F the effective R-value loss for fiberglass started and
reached 50% at 10°F. Loose-fill cellulose insulation tests by Oak Ridge in a Large Scale Climate
Simulator found the effective R-value actually increased slightly to temperatures as low as -18°F.
A simple solution to fixing the loose-fill fiberglass degradation is to add 2 to 3 inches of
cellulose on top or use cellulose initially.
Scientists, engineers, and contractors have realized for many years that the most commonly-used
building insulation material isn't really the best insulator. Now this "conventional wisdom" of
energy conservation has been confirmed and quantified through scientific studies at one of the
world's leading research universities.
Energy shoot-out at the CU corral
In December 1989 and January 1990 the University of Colorado at Denver School of Architecture
and Planning studied the energy conservation efficiency of two test buildings that differed only
in the insulation systems that had been installed.
Building “A” was insulated with 5.5 inches of cellulose wall cavity spray in the walls and
R-30 of loose fill cellulose in the ceiling.
Building "B" received R-19 unfaced fiberglass batts in the walls and R-30 kraft faced batts
in the ceiling.
Over the two month period a number of different tests and measurements were performed.
Here's what the CU Denver researchers learned.
In spite of the fact that tests showed Building "B" was about 12% tighter than Building "A"
in the uninsulated state, after insulation was installed Building "A” was far tighter than "B".
Calculations showed that cellulose tightened the building 36% to 38% more than fiberglass.
An overnight heat loss test revealed that after nine hours (midnight to 9 a.m.) the
cellulose-insulated building was 7 degrees F warmer than the fiberglass building.
Most significantly, after three weeks of monitoring the cellulose-insulated building has
used 26.4% less energy to heat than the fiberglass building.
In their statement of conclusions the researchers note that the results suggest cellulose
performs as much as 38% better than fiberglass. The performance advantage of cellulose in
temperate climates appears to be about 26%, and the report projects that "this benefit
would become more significant in more severe climates."
All residential structures contain large amounts of wood. Cellulose insulation is the only
wood-based building material that is always treated for fire retardancy. This makes cellulose
insulation one of the safest materials used in home construction.
If a fire occurs the dense structure of cellulose and its fire retardants slow its spread
through the building by blocking flames and hot gases and restricting the availability of
oxygen in insulated walls and ceilings.
AFT's cellulose insulation has been treated with fire retardants and has a Class 1 fire rating.
Strict flammability standards of the Consumer Product Safety Commission must be met. AFT uses
microprocessors/load cells to gravimetrically integrate the ratio of chemical to fiber to
ensure a uniform and correct level of fire retardants. The borates added as fire retardants are
less toxic than common table salt.
In several demonstration burns, buildings with cellulose have retained structural integrity
significantly longer than buildings with other fiber materials. In one demonstration the
ceiling of a fiberglass insulated building collapsed 22 minutes after ignition while the
cellulose stayed in place for 70 minutes, an important margin of safety for building occupants.
The National Research Council Canada (NRCC) added scientific support to the fire safety benefits
of cellulose insulation in a 1994 study. This study concluded that fiberglass reduced the fire
resistance of insulated assemblies while cellulose insulation improved fire resistance 22% to 55%.
NRCC tested a cellulose insulated floor/ ceiling assembly in 1995 and found it to have
approximately 50% higher fire resistance than a fiberglass insulated assembly. The cellulose
assembly resisted direct fire exposure about 30 minutes longer than the fiberglass test assembly.
A cellulose insulated wall tested in 1999 by Omega Point Laboratories was found to be up to 77%
more fire resistance than an uninsulated wall.
As a result of this fire resistance, under some fire conditions, cellulose give building
occupants more time to reach safety and fire fighters more time to save the structure.
Cellulose insulation benefits not covered by the University of Colorado study include:
AFT's cellulose insulation, is extremely effective in controlling sound transmission in walls,
floors, and ceilings because of cellulose insulation's higher density and ability to fill the
gaps and create, a seamless Wall cavity or ceiling. Noise is trapped by the same properties
that provide superior resistance to air infiltration.
Cellulose insulation contains more than 8O% recycled material, primarily newsprint, one of the
largest parts of the waste stream. Cellulose insulation not only saves energy, it helps cities
meet the growing waste disposal challenge.
Since production of cellulose requires much less energy than mineral fiber insulation, which
is made in gas-fired furnace's, and foam plastics, which are petrochemicals, the "embodied
energy" in cellulose insulation is much lower per "R" of insulating value than other materials.
Cellulose consumes less , energy when it's made and saves more energy after it's installed.
If you're serious about saving money heating and cooling your home, about recycling and
responsible use of resources, and about saving energy for our country the only insulation
to seriously consider is cellulose.
Cellulose insulation is covered by the most comprehensive legal and voluntary standards of any
insulation material. To be sold at all cellulose insulation must meet the requirements of Consumer
Products Safety Commission Safety Standard 16 CFR Part 1209. Most cellulose producers adhere to
the more comprehensive American Society for Testing and Materials standards C-739 for loose-fill
cellulose insulation and C-1149 for self supporting spray-applied cellulose insulation. The
Federal Trade Commission R-Value Rule applies to cellulose -- as it does to all residential
thermal insulation -- assuring honesty and accuracy in marketing and labeling.
A number of qualified independent product testing laboratories have cellulose insulation
certification programs to assure contractors and consumers that the material they buy and
install meets or exceeds government and industry standards. The National Association of
Home Builders National Research Center certifies the quality and performance of cellulose
The labels of Underwriters Laboratories, the United States Testing Company, and other
NAVLAP-approved laboratories, or the seal of the NAHB Research Center, are reliable
indicators of safe, effective cellulose insulation that conforms with all federal and industry
If you want insulation that's best for the nation's energy security, the environment, and your
pocketbook, choose CELLULOSE!
Approved under all codes
Cellulose insulation is subject to the strict flammability and corrosiveness standards
established by the Consumer Products Safety Commission. The BOCA National Building Code,
the SBCCI Standard Building Code, the ICBO Uniform Building Code, the CABO One and Two
Family Dwelling Code, and the new codes published by the International Code Council
all contain cellulose insulation requirements that are consistent with the CPSC standard:
The ICC codes also recognize the fire safety advantages of cellulose by permitting
installation of electrical boxes on opposite sides of fire rated walls if the boxes are
separated by as little as 3 1/2 inches of cellulose insulation. In walls with fiber glass
the required separation is 24 inches.
Cellulose....it's naturally better insulation
Still not convinced of the Superiority of Cellulose Insulation?
Then please read the following pages.
R-TEK Insulation is your insulation contractor of choice.
If you have any questions regarding commercial or home insulation please do not hesitate
to call us at: (330) 753-8394. We will be more than happy to assist you.