From the very first cave dwellers to the super-insulated house,
man has understood the need for protection from the elements. Organic materials
have served as the natural prototype for thermal insulators. Like fur covering
the polar bear or feathers on a bird, cotton, wool, straw, even hair are evolutionary examples of
insulation. Pre-historic man clothed himself with wool and skins from animals.
He built homes of wood, stone, earth, and other materials for protection from
the cold winter and the heat of summer.
The true origins of the science of thermal insulation, however, are
difficult to identify.
For thousands of years, house structures were designed to
best suit the climate of their location. For example, using the earth as an
insulator, the Egyptians retired to the coolness of subterranean chambers and grottoes
on hot days. Historians believe the
Ancient Greeks and Romans discovered asbestos and found many uses because of
its resistance to heat and fire. The Romans even used cork for insulation in
shoes in order to keep their feet warm. Pliny, in the first century, referred
to the use of cork as an insulating material for roofs. Early inhabitants of
Spain lined their stone houses with cork bark and North African natives used
cork mixed with clay for the walls of their dwellings.
As technology developed, so did innovations to improve man’s
comfort. The introduction of the fireplace and chimney by the Norwegians and
people of Iceland during the 12th and 13th centuries provided controlled,
artificial heat. It was evident that
the task soon became how to not only keep heat out , but to also, how to keep heat in. The thatched huts of Northern
Europe were built with a roof, up to 2 feet thick, of woven straw and walls of
clay and straw. (see Figure 1-1) Early
Spanish Mission Houses of the southwestern United States, where temps rose to
120-140 degrees, were comparatively cool due to clay straw walls several feet
thick. Similarly, the indigenous peoples
of the South Seas built huts of dried sea grass. The hollow fiber of the dried
sea grass provided a good degree of thermal resistance. Mineral fiber - another important insulating
material - was first used by the natives of the Hawaiian Islands to blanket
their huts. The fibers came from volcanic deposits where escaping steam had
broken the molten lava into fluffy fibers.
It was not until the advent of the industrial revolution of
the late 19th century that deliberate commercial application of thermal
insulations becomes mainstream. For example, blanket type insulations were
being developed throughout the 1890’s. One such product, known as “Cabot’s
Quilt”, was introduced by Samuel Cabot in 1891. The material consisted of a
matting of Zostera Marina, a marine plant also known as Eel Grass, sandwiched
or stitched between two layers of Kraft paper. ( An unrefined use of this
material was found in The Pierce House of Dorchester Massachusetts, built in
1635 with Zostera Marina stuffed between the framing members.)
Mineral Wool was first commercially produced as a pipe
insulator in Wales in 1840. It was produced in the United States for the first
time in 1875. It was almost 60 years
later, in 1897, C.C. Hall, a chemical engineer, produced rock wool. By 1901, he
was producing this product commercially at a plant in Alexandria ,
Indiana. Hall formed a partnership to
make the new product and later founded Banner Rock Products Co. (which was
purchased by Johns Manville Co. in 1929.) By 1928, there were eight plants
manufacturing either rock wool or slag wool insulation in the United States. (By
the 1950’s, this number had increased to approximately 90 but has since
declined to about fifteen to twenty today. )
Fiberglass had its first beginnings in ancient Egypt when
people discovered they could draw hot glass into threads which were placed around
vessels for decoration. The modern technique of making fiberglass insulation,
developed in 1931, involves jetting of molten glass through tiny heated holes
into high-speed air streams wherein the resulting fibers are drawn very thin
and to great length. Developed by
Owens-Illinois, Corning Glass Company, and later known as Owens-Corning
Fiberglass, was the sole producer until an anti-trust action filed in 1949 by
the Department of Justice.
Wood shavings, were once a very popular insulation product
due to the wide availability of raw materials and low cost at the turn of the
century. Shavings were often treated with lime or other chemicals, to increase
resistance to water absorption, fire and fungal growth. These were called balsa
wool or "balsa batt" (actually sawdust wrapped in paper), and were
popular in homes of Northeastern United States.
Straw bale construction has also been around since “frontier
days” of the United States. Nebraska residents have used straw for a building
material for over 100 years. When the Kincaid Act of 1904 opened up the part of
Nebraska that includes the Sandhills to homesteading, straw was one of the only
indigenous materials available. Housing became an urgent necessity for
frontiersman and straw bale construction flourished in the Sandhills of
Nebraska more than any other known location. Although these settlers planned to
build a "real" house as soon as enough money could be saved, such
houses were often left exposed on the outside, while plastered on the inside to
enhance tidiness and prevent drafts. When the owners finally believed that they
were living in a "real" house, a process that sometimes took as much
as ten years, the outside walls would finally get a thick coat of mud plaster
or cement stucco.
Although straw bale construction was an appropriate,
sometimes necessary, response to a unique combination of legislative, geologic,
natural resource and socio-economic factors that prevailed in that region, the
building of railroads through the midwest is one factor that added to the
reduction of straw use. Railroads and merchandizing enabled wood products to
replace Nebraska's indigenous materials for buildings needs.
Reflective insulation materials, using bright metallic
surfaces, were first patented in 1804.
Aluminum eventually became the predominant reflective material, but not
achieving commercial popularity until the 1930’s.
The
genesis of insulation board products dates to 1910. Two semi-rigid insulation
products made from flax (a textile fiber made from plants) were manufactured in
Minnesota, called “Flaxlinum” and “Fibrofelt”. These were ultimately replaced
by Rigid Insulation board products, also
first produced in Minnesota, in
1914. “Insulite” was manufactured by taking wood pulp waste products, known as
sulfite screenings, and processing and drying them into a rigid, lightweight insulating material.
This plant produced up to 60,000 square feet of Insulite per day. By 1920, Celotex Company introduced an
insulating board made from bagasse, a waste by-product of sugar cane after the
juice has been extracted. This was
followed by Celotex’s Cenesto, a fire resistant insulation board surfaced on
one or both sides with asbestos cement, used primarily for low-cost housing. Lower density insulation boards, generically
belonging to the family of fiberboard products,
were available in thicknesses ranging from 7/16 “ to 1” and in some
cases up to 3”. Fiberboard insulation was commonly used as an insulating lath
over the wood studs, a plaster base over masonry and even in some cases as an
interior finish.
The 1920’s saw a rise in public awareness of the value of
thermal insulation. While fiberboard was
advertised as the most economical insulation of its time, batts began a rise in
popularity as well. Aluminum and copper were also applied to the batts as
reflective foils. Slag wool is a
material made by blowing steam through fluid slag (molten rock). Also known as
rock wool, this product was later replaced by asbestos, similar in appearance
and promoted as the best alternative by heating engineers who dealt with the
control and handling of steam. Glass
fiber production started in the mid-1930’s.
The case can also be made that insulation was not as
necessary due to the construction materials and methods prior to this time.
Materials were heavier, including windows and door sashes, which provided
adequate weather resistance. The growing
popularity and use of lighter building materials increased the need for
insulation products. The gradual
introduction of air conditioning systems into home design also contributed to a
greater need for thermal insulation.
In 1928, the Milam Building in San Antonio, Texas became the
first high-rise office building to be completely air conditioned. That same
year, Willis Carrier installed the first residential unit air conditioner,
called the "Weathermaker" , which heated, cooled, humidified, cleaned
and circulated air in homes. One year
later, in 1929, the Frigidaire division of General Motors introduced its first
room cooler. Several other
manufacturers, including York and General Electric, began to offer room coolers
soon after. The first window air conditioners were developed in the 1930’s,
however it was 1936 when Philco-York introduced a 3,675 btu/h window unit.
Popularity increased throughout the next two decades sales of window units
approaching 300,000 in 1952. The early 1950’s also saw the evolution of smaller
central air conditioning systems, using water cooled condensers, become more
commonplace in residential use.
During World War II, the use of building insulation was made
mandatory to conserve metal required for heating and air conditioning equipment
and to save fuel. This probably contributed to a greater awareness
by the general population as to the sensible applications of insulation in
residences as well. This was explored further by a special report developed by
the Secretary of Defense in 1957. “Capehart” housing was rented to civilian
employees at remote military institutions. The study concluded that if the 72,000
“Capehart Act’ houses would have been designed to sufficient thermal standards,
the United States government, which pays the heating bill as part of the rent,
would save $52 million over a thirty year period.
Extruded polystyrene insulation was originally developed by
the Dow Chemical Company in the USA in the early 1940's. Known proprietarily as
STYROFOAM , it was first used as a flotation material in liferafts and
lifeboats as its fully closed cell structure renders it highly resistant to
water absorption.The insulating properties of STYROFOAM extruded polystyrene
foam, combined with the advantage of the closed cell structure, led to its
development as a thermal insulation material. Initial applications were in low
temperature situations for cold store floors, wall and ceiling panels, and pipe
insulation. In the 1950's, Dow's
extruded polystyrene foam extended its impact to other areas of the
construction industry - as a thermal insultant in commercial and residential
buildings.
The domestic perlite industry began in the 1940’s. This
process involved the processing and expanding of crude perlite, a type of
volcanic glass. At about the same
time, as the U.S. paper industry grew,
it was only natural to look to paper byproducts for insulation. Originally
manufactured as a sound deadener, paper-based cellulose soon caught on as an
effective, dense insulation material. But early cellulose insulation didn’t
benefit from today’s fiber technology and application equipment, so it remained
a small portion of the market as fiberglass became increasingly popular after
World War II. (Cellulosic fiber
insulation had several patents issued in the 19th century but gained little if
any popularity. )
The 1970’s saw a dramatic shift in public awareness and
sensibility towards energy conservation. The production of domestic oil had
peaked in 1970, which subsequently created a greater dependence on foreign
exports. Many researchers point to the Arab oil embargo in 1973 and 1974 as the
catalyst for the energy crisis. A second sharp rise in oil prices occurred in
1979 following the Iranian revolution further contributed to public discussion
as well as new energy programs. Government mandates have continued this trend
with the Federal Energy Management Improvement Act (FEMIA) of 1988 that
required a10% reduction in per-square-foot energy use by Federal buildings
between 1985 and 1995 followed by the sweeping Energy Policy Act of 1992
(EPACT). This Act increased conservation and energy-efficiency requirements for
government, energy, and consumers. Federal agencies, for example, were required
to attain a 20% reduction in per-square-foot energy consumption by 2000
compared to a 1985 baseline. All of
these initiatives not only contributed to a greater awareness of energy conservation
by the general public but greater emphasis by producers, installers and
designers on insulation installation materials and methods.
Cellulose insulation has been produced and installed in new
and existing homes for more than 40 years. As a result of the 1970’s Energy
Crisis, heavy demand for insulation induced many new producers to enter the
cellulose industry, causing a resurgence of cellulose insulation popularity.
Once the crisis passed, however, only a few companies remained committed to
refining the material.
Urea formaldehyde foam insulation (UFFI) was introduced to
the building industry in 1960. Health complaints started from the occupants of
UFFI insulated homes in 1978 and by 1980,
Urea formaldehyde foam insulation was banned across Canada, reportedly
due to long term health risk to occupants of houses insulated with UFFI. (Urea formaldehyde is one of the main resin
mixtures of formaldehyde, and of all the formaldehyde compounds contributes the
most to indoor air problems, due to its water solubility.)
{A} References
Albert
Farwell Bemis, The Evolving House, ( The Technology Press, Cambridge MA,
1933),107.
T.
Neil Davis , Alaska Science Forum , Fiberglass Insulation, Article #482, ,
April 30, 1981
Thomas
C. Jester, Twentieth Century Building Materials, (McGraw Hill, New York, 1995),
122.
Paul
Dunham Close, Thermal Insulation of Buildings, (New York: Reinhold Publishing
Corporation, 1947), 12.
Henry
S. Harrison, Houses- The Illustrated Guide to Construction, Design &
Systems, (Residential Sales Council, Chicago, 1998), 202.
Carrier
& United Technologies website;
http://www.carrier.com/final/innovations/history/history3.html
Mike
Pauken , P.E., “Sleeping Soundly on Summer Nights”, ASHRAE Journal, May 1999,
p. 42-44.
Tyler
Stewart Rogers, Thermal Design of Buildings, (John Wiley and Sons, New York,
1964), p.2.
J,D.
Nisson & Gautam Dutt, The Superinsulated Home Book, (John Wiley & Sons,
New York, 1985) Appendix A.
GreenStone, Cocoon and
"Simply Smarter Insulation" are trademarks of GreenStone, a
Louisiana-Pacific
company. Copyright© 1997 GreenStone Industries.
Cellulose
Insulation Manufacturers Association website press release,
http://www.cellulose.org/press.htm
The Residential Energy Efficiency Database (REED) ,
http://www.its-canada.com/reed/iaq/uffi.htm
