In 2007, coffee was grown on 2.3 million hectares, mainly in the states of São Paulo and Minas Gerais, with a production of 2.2 million metric tons.. Brazil is also the world’s biggest p
Trang 1Rice is produced on about 3 million hectares,
though the 11 million metric tons produced are mainly
consumed within Brazil Similarly, the 3.9 million
metric tons of cotton grown on 1.1 million hectares of
land support Brazil’s significant textile industry In
2005, approval was given for cotton farmers to use
ge-netically modified strains Brazil is one of the top-ten
producers of textiles
Two other major Brazilian exports include coffee
and orange juice In 2007, coffee was grown on 2.3
million hectares, mainly in the states of São Paulo and
Minas Gerais, with a production of 2.2 million metric
tons Oranges were cultivated on 0.8 million hectare,
mostly in the state of São Paulo, from which 18.2
mil-lion metric tons were produced Brazil is the world’s
largest producer of coffee and is responsible for about
one-third of world production It is also a leading
exporter, mainly to the United States and Europe;
in 2007, exports comprised twenty-eight million
60-kilogram bags, which earned $3.4 billion Brazil is also the world’s biggest producer of orange juice; produc-tion in 2005 amounted to 1.4 million metric tons out
of a world total of 2.4 million metric tons Only about
2 percent is consumed internally, while the other 98 percent is exported
Cattle meat (notably beef and veal), pork, and chickens/chicken meat are important components
of Brazil’s agriculture and export earnings Cattle ranches are prevalent in the west-central region, though ranching has expanded north, and illegal grazing is now a major cause of Amazon deforesta-tion Brazil has the largest cattle industry in the world, with more than 200 million head of cattle It is also a leading exporter of beef, mainly to Europe and Chile, with exports amounting to 80 million metric tons per month, and the industry continues to expand Pig rearing is also important in Brazil’s agricultural sec-tor, with about 34 million head The three southern
The Brazilian Amazon jungle is a source of numerous natural resources but has suffered from major deforestation
(©Paura/Dreams-time.com)
Trang 2states dominate production, but pig rearing has spread
to the center-west region, especially in the state of
Mato Grosso Russia and Eastern Europe constitute
the major overseas markets; domestic demand is also
high Chicken meat is another significant export,
no-tably to Asia In 2007, Brazil had almost 1 billion
chick-ens and is second to the United States as an exporter
of chicken meat The value of its exports was $5 billion
in 2007 It produces 12 million metric tons annually
Wood and Wood Products
As well as being home to the world’s largest extent of
tropical forest in the Amazon basin, Brazil has 6.2
mil-lion hectares of plantation forests, comprising
fast-growing pine and eucalyptus These were planted
mainly between 1967 and 1987, a process stimulated
by tax incentives, as some 70 percent of the land used
is publicly owned The plantations produce all of
Brazil’s pulp and paper, which generated about $3
bil-lion, or 40 percent of the total GDP earned by the
for-est sector Most sawn wood is produced from natural
forests, of which Brazil has lost an area the size of
France
A conflict of interest between conservation and
for-estry has arisen, especially in relation to the serious
problem of illegal felling Approximately 30 percent
of the Amazon forest has protected status, and most
wood is removed from the 25 percent that is privately
owned Prior to extraction, landowners must have a
management plan and a permit from Brazil’s
environ-ment agency Only 5 percent of wood is approved
by the international Forest Stewardship Council
Am-azonian forests, especially those in the states of Pará,
Mato Grosso, and Rondônia, generate more timber
than any other forests in the world Most of this
wood is used within Brazil itself Many other forest
products are significant resources, including
char-coal, fuelwood, nuts, fruits, oil plants, and rubber
Other Resources
Brazil produces a range of precious and semiprecious
stones, including diamond, emerald, topaz,
tourma-line, beryl, and amethyst These come mainly from
the states of Minas Gerais, Rio Grande do Sul, Bahia,
Goiás, Pará, Tocantins, Paraíba, and Piauí Both raw
and cut stones are exported, especially to the United
States, and they also support an internal jewelry
in-dustry
Brazil is a significant producer of graphite,
mag-nesite, and potash and has abundant sand and gravel
deposits It has almost 30 percent of the world’s graph-ite reserves, which are widely distributed The richest deposits are in Minas Gerais, Ceará, and Bahia About
22 percent is exported, and the remainder is used do-mestically in the steel industry and for battery produc-tion Reserves of magnesite are also extensive, rank-ing Brazil fourth in the world The deposits occur in the Serra das Éguas, in the state of Bahia About 30 percent is exported and 70 percent is used in a variety
of Brazil’s industries, especially steel manufacture In
2005, some 403 metric tons of potash were produced from Sergipe and Amazonas, where deposits of sil-vinite are located This makes Brazil the world’s ninth largest producer, though it continues to import most
of its potassium fertilizer Phosphate deposits also sup-ply fertilizer, and in 2006, Brazil’s production com-prised almost 6 million metric tons, making it the twelfth largest producer in the world It contributes substantially to crop production, as Brazil is the world’s fourth largest consumer of fertilizers, and is also used for manufacturing detergents
A M Mannion
Further Reading Brazilian Development Bank and Center for Strategic Studies and Management Science, Technology, and
Innovation Sugarcane Bioethanol: Energy for Sustain-able Development Rio de Janeiro: Author, 2008.
Goulding, Michael, Ronaldo Barthem, and Efrem
Jorge Gondim Ferreira Smithsonian Atlas of the Am-azon Washington, D.C.: Smithsonian Books, 2003 Lusty, Paul South America Mineral Production, 1997-2006: A Product of the World Mineral Statistics Data-base Nottingham, Nottinghamshire, England:
Brit-ish Geological Survey, 2008
Web Sites Energy Information Administration Country Analysis Briefs: Brazil
http://www.eia.doe.gov/emeu/cabs/Brazil/
Oil.html Infomine Brazil: Great Potential http://www.infomine.com/publications/docs/ InternationalMining/IMMay2006a.pdf See also: Agricultural products; Agriculture indus-try; Biofuels; Ethanol; Timber industry
Trang 3Category: Products from resources
Brick as a building material has a long history Its
qualities of durability and ease of manufacture—as
well as the fact that suitable clay is widely available—
have made it desirable.
Definition
Brick has been used as a building material since
be-fore the advent of written history Bricks are durable,
fireproof, and decorative They also have high
heat-and sound-insulating qualities The clay from which
bricks may be made is widespread on the Earth’s
sur-face Clay can be used directly if it is relatively free of
impurities In such cases the clay is formed, dried, and
fired Clays that are suitable but contain some
unde-sirable elements, such as roots or pebbles, can be
re-fined through removal of the unwanted material
Overview
Clay resources for brick making are usually mined by
open-pit or strip mining In small mining operations,
hand labor may serve to remove the overlying earth
material (overburden) In larger operations, a
combi-nation of mechanical devices is used Graders and
drag lines may be used to remove the overburden and
expose the clay Once the clay has been removed, it is
ready for preparation
The complexity of clay preparation depends on
the quality of the clay Primary preparation involves
crushing the raw material, removing stones, and
blend-ing different clays if desired Secondary preparation
grinds the crushed lumps to the desired fineness At
this stage, more blending may occur; storage of the
milled clay follows
The manufacture of bricks begins when the
pro-cessed clay is moistened enough to permit formation
of bricks In some instances hand molding is used; in
other cases the brick material may be extruded and
cut into lengths of the desired size Once the bricks
have been produced, they must be dried prior to
fir-ing The preliminary drying is necessary to reduce the
water content, because too much water could cause
problems resulting from expansion during the firing
process Drying is done by placing the bricks either in
a protected place to allow natural drying or in an
arti-ficially heated dryer
Following the drying process, the bricks are ready for firing Firing removes the remaining moisture from the bricks and, as the intensity of the heating increases, renders the brick stable and able to resist weathering The firing itself can be done in the open, with the fuel and prepared bricks intermixed More controlled fir-ing takes place with the use of kilns, in which the firfir-ing occurs under closed, controlled conditions Follow-ing firFollow-ing, the bricks are allowed to cool slowly to pre-vent damage and are then ready for use
Jerry E Green
See also: Cement and concrete; Clays; Open-pit min-ing; Strip mining
Bromine
Category: Mineral and other nonliving resources
Where Found Bromine is widely distributed in small quantities in the Earth’s crust The oceans contain most of the world’s bromine, and it is also found in inland evap-oritic (salt) lakes Recovered from underground brines
in Arkansas, bromine became that state’s most impor-tant mineral commodity and made the United States the producer of one-third of the world’s bromine In descending order, Israel, China, Jordan, and Japan account for most of the balance
Primary Uses The use of bromine in flame retardants is a quickly expanding industry Bromine is also used in agricul-tural applications, water treatment and sanitizing, petroleum additives, well-drilling fluids, dyes, photo-graphic compounds, and pharmaceuticals
Technical Definition Bromine (abbreviated Br), atomic number 35, be-longs to Group VII (the halogens) of the periodic ta-ble of the elements and resemta-bles chlorine and io-dine in its chemical properties It has two naturally occurring isotopes: bromine 79 (50.69 percent) and bromine 81 (49.31 percent) Bromine is the only non-metal that is liquid at room temperature A volatile liq-uid, it is deep red in color with a density of 3.14 grams per cubic centimeter, a freezing point of−7.3° Celsius, and a boiling point of 58.8° Celsius A diatomic
Trang 4ment, bromine exists as paired bromine atoms in its
elemental form
Description, Distribution, and Forms
Bromine has an abundance of 2.5 parts per million in
the Earth’s crust, ranking it forty-sixth in order of
abundance of the elements It is more prevalent in the
oceans, at 65 parts per million In salt lakes such as the
Dead Sea, at 4,000 parts per million, and Searles Lake
in California, at 85 parts per million, bromine is more
abundant than in the oceans The most concentrated
sources of bromine are brine wells; one in Arkansas
has 5,000 parts per million
As a halogen, bromine needs one electron to
achieve filled “s” (sharp) and “p” (principal) shells
Thus, bromine exists in nature as a bromide ion with a
negative 1 charge High concentrations of bromine in
plants have not been noted However, marine plants
do have a relatively higher concentration than land
plants
Bromine, along with chlorine, tops the list of ele-ments suspected of causing ozone depletion in the stratosphere Because of this, the Environmental Pro-tection Agency has listed methyl bromide and hy-drobromofluorocarbons as a class I ozone-depleting substances This classification means a limit to the production of these compounds in the United States Because availability has become more common be-cause of pesticides and gasoline additives, the human intake of bromine has increased There have not been toxicity problems, however, as bromine is retained for only short periods before it is excreted in urine Plant and animals alike show little toxic reaction to bro-mine
History Antoine-Jérôme Balard first established bromine as
an element He had extracted bromine from brine by saturating it with chlorine and distilling When at-tempts to decompose the new substance failed, he
Data from the U.S Geological Survey, U.S Government Printing Office, 2009.
2,000
135,000
1,600 1,500
165,000 20,000
70,000
3,000 Withheld
Metric Tons of Bromine Content
175,000 150,000
125,000 100,000
75,000 50,000
25,000 Ukraine
Israel
India
Germany
China
Azerbaijan
Japan
Jordan
United States
U.S data were withheld to avoid disclosure of company proprietary data.
Note:
World Bromine Production, 2008
Trang 5correctly deduced that bromine was an element and
published his results in 1826 Balard wanted to call the
new element “muride,” but the French Academy did
not like the name Bromine, from the Greek bromos,
for stink or bad odor, was chosen instead The first
mineral of bromine found was bromyrite (silver
bro-mide), found in Mexico in 1941 Silver bromide was
used as the light-sensitive material in early
photo-graphic emulsions from about 1840, and potassium
bromide began to be used in 1857 as a sedative and an
anticonvulsant The purple pigment known as Tyrian
purple and referred to in Ezekiel in the Old
Testa-ment of the Bible is a bromine compound Originally
the dye was obtained from the small purple snail
Murex brandaris.
Obtaining Bromine
Acidified solutions of bromine (either brines or
sea-water) are pumped into the top of a ceramic-filled
tower As the solution falls through the tower, the
bro-mine reacts with chlorine The chlorine becomes
chloride ions dissolved in solution The bromide ions
in solution become bromine molecules The bromine
is then steamed out (collected in steam) or blown out
(collected in air) by the steam or air passing through
the tower The bromine condenses and is separated
from the gases at the top of the tower It then can be
purified or reacted with other substances to form
bro-mine compounds In Israel, the brine comes from the
production of chemicals such as sodium chloride or
potash and contains about 14,000 parts per million
Yearly world production of bromine in 2008 was about
400,000 metric tons (excluding U.S production)
Uses of Bromine
Flame retardants use the highest percentage of the
bromine produced, about 45 These products are
used in circuit boards, television cabinets, wire, cable,
textile coverings, wood treatments, fabric treatments,
polyurethane foam insulation, and polyester resins
Bromine compounds are used in portable fire
extinguishers as well as in closed spaces such as
com-puter rooms Use of bromine in agriculture as
pesti-cides such as ethylene bromide,
dibromochloropro-pane, or methyl bromide accounts for 10 percent of
the total produced Methyl bromide is a very
effec-tive nematocide (worm killer) as well as herbicide,
fun-gicide, and insecticide Bromine is also used in treating
water and sanitizing water equipment such as
swim-ming pools, hot tubs, water cooling towers, and food
washing appliances Bromine is more efficient than other materials because it has a higher biocidal activity
In the 1970’s, the principal use of bromine was
in ethylene dibromide, a scavenger for lead With the decreased use of leaded gasoline, less ethylene dibromide is needed High-density drilling fluids made with bromine compounds account for another 20 cent Dyes and photography usage account for 5 per-cent Silver bromide is still the main light-sensitive compound used in film The pharmaceutical industry uses about 4 percent of the bromine produced Be-cause bromine is very reactive, forming compounds with every group except the noble gases, new uses for bromine will undoubtedly be found
C Alton Hassell
Further Reading Greenwood, N N., and A Earnshaw “The Halogens: Fluorine, Chloride, Bromine, Iodine, and
Asta-tine.” In Chemistry of the Elements 2d ed Boston:
Butterworth-Heinemann, 1997
Henderson, William “The Group 17 (Halogen) Ele-ments: Fluorine, Chlorine, Bromine, Iodine, and
Astatine.” In Main Group Chemistry Cambridge,
En-gland: Royal Society of Chemistry, 2000
Jacobson, Mark Z “Effects of Bromine on Global
Ozone Reduction.” In Atmospheric Pollution: History, Science, and Regulation New York: Cambridge
Uni-versity Press, 2002
Kogel, Jessica Elzea, et al., eds “Bromine.” In Indus-trial Minerals and Rocks: Commodities, Markets, and Uses 7th ed Littleton, Colo.: Society for Mining,
Metallurgy, and Exploration, 2006
Krebs, Robert E The History and Use of Our Earth’s Chemical Elements: A Reference Guide Illustrations by
Rae Déjur 2d ed Westport, Conn.: Greenwood Press, 2006
Massey, A G “Group 17: The Halogens: Fluorine,
Chlorine, Bromine, Iodine, and Astatine.” In Main Group Chemistry 2d ed New York: Wiley, 2000 Weeks, Mary Elvira Discovery of the Elements: Collected Reprints of a Series of Articles Published in the “Journal
of Chemical Education.” Kila, Mont.: Kessinger, 2003.
Web Site U.S Geological Survey Bromine: Statistics and Information http://minerals.usgs.gov/minerals/pubs/
commodity/bromine/index.html#myb
Trang 6See also: Agriculture industry; Air pollution and air
pollution control; Atmosphere; Clean Air Act;
Envi-ronmental Protection Agency; Herbicides; Oceans;
Ozone layer and ozone hole debate; Pesticides and
pest control
Bronze
Category: Products from resources
Bronze is a term applied to a variety of alloys that
con-tain copper; the oldest of these, which was the first
me-tallic alloy produced, is an alloy of copper and tin.
Other alloying elements include tin, nickel,
phospho-rus, zinc, and lead.
Background
A variety of related alloys are called bronze The one
with the longest history is an alloy composed
primar-ily of copper, with a smaller percentage of tin Various
forms of bronze have been smelted for thousands of
years; in fact, bronze was the first true metallic alloy
developed Bronze replaced the use of copper as the
material of choice for tools, weapons, jewelry, and
other items in the ancient Near East and other early
centers of civilization Although eventually it was
largely replaced by iron and finally by various steel
al-loys, bronze still is employed extensively for a variety
of industrial uses worldwide
History
The first metal used by ancient metallurgists was
cop-per, because surface deposits of this metallic element
in its native, or naturally pure, form were once
rela-tively plentiful in certain areas However, objects
pro-duced from pure or nearly pure copper possess
sev-eral drawbacks, chief among them are softness and
lack of resistance to damage Archaeological finds
from the Near East dating back at least to around 3000
b.c.e indicate that early metalworkers discovered that
by adding other metals in small percentages, they
could produce a new, stronger metal that also boasted
several other favorable characteristics: a lower
melt-ing point (950° Celsius instead of the 1,084° Celsius
required for copper), greater ease of flowage into
molds in the casting process, and elimination of the
troublesome bubbles that plagued the casting of pure
copper
Through experimentation, early metallurgists dis-covered that the ideal metal proportions for bronze were about 10 percent tin and 90 percent copper The invention of bronze led to a veritable explosion of metal-casting industries that produced elaborate and intricate bronze artifacts and ushered in a period of flourishing mining and trading networks linking far-flung areas for bronze production Some bronze-producing centers, such as sites in ancient China, ex-perimented with bronze using other admixtures, such
as lead Eventually, with the development of hotter smelting furnaces and other techniques, bronze was replaced for most of its applications by a still harder metal, iron, and then by the various alloys of steel Various bronze alloys, however, have always been employed for some uses even while other metals be-came the primary choice for most metal applications Statuary made from bronze, for example, has always enjoyed popularity In addition, the modern industrial world uses various types of bronze for cast products such as pumps, gears, nuts, tubes, rods, and machine
or motor bearings Modern bronze alloys typically do not have a tin content in excess of 12 percent, as per-centages above that ratio produce alloys with declin-ing ductility (the capaciity for bedeclin-ing easily shaped or molded), and they tend to become very brittle
Specialized Bronzes Some specialized modern bronze alloys are produced with small percentages of lead, nickel, phosphorus, zinc, and even aluminum Copper-tin-lead bronzes, for example, are used for machine bearings that must withstand both a heavy load and frictional heat The lead is added to produce a desired degree of elasticity
A bronze combining copper, tin, and phosphorus is smelted with a percentage of phosphorus in the range
of 0.1 to 0.5 percent The phosphorus in this alloy al-lows the molten metal to flow more freely and makes casting easier It also helps deoxidize the melt during the smelting process and produces a bronze with great resistance to wear Phosphor bronzes, as they are termed, are used in machine gear wheels, an applica-tion where hardness and wear resistance are desired Another type of bronze that is similarly employed is zinc bronze The zinc typically makes up 2 to 6 per-cent of the alloy, which also includes copper and tin Another term for zinc bronze is “gunmetal” bronze, and if the alloy has the specific formula 88 percent copper, 10 percent tin, and 2 percent zinc it is termed
“admiralty gunmetal” bronze
Trang 7Yet another type of bronze is copper-tin-nickel
bronze, in which the proportion of nickel is usually 1
to 2 percent of the alloy Nickel bronze is designed to
withstand high temperatures and strongly resist
cor-rosion It possesses a microstructure that is more
closely grained than most bronzes, while having both
added toughness and strength Other types of bronze
alloys include aluminum bronzes, which typically are
1 to 14 percent aluminum and usually have smaller
percentages of other metals, such as iron, nickel, and
manganese Aluminum bronzes are used in the
pro-duction of special wires, strips, tubings, and sheets for
which ductile strength is desirable
A by-product of exposure to the elements of bronze
alloys that are less resistant to corrosion is the
produc-tion of a thin greenish or greenish-blue crust or
pa-tina called “verdigris.” This crust, often seen on
out-door statuary, fixtures, and fountains, is composed
typically of either copper sulfide or copper chloride
Frederick M Surowiec
Further Reading
Callister, William D “Nonferrous Alloys.” In Materials
Science and Engineering: An Introduction 7th ed New
York: John Wiley & Sons, 2007
Cverna, Fran, ed “Bronzes.” In Worldwide Guide to
Equivalent Nonferrous Metals and Alloys 4th ed
Ma-terials Park, Ohio: ASM International, 2001
Hummel, Rolf E Understanding Materials Science:
His-tor y, Properties, Applications 2d ed New York:
Springer, 2004
Raymond, Robert Out of the Fiery Furnace: The Impact of
Metals on the History of Mankind University Park:
Pennsylvania State University Press, 1986
Simons, Eric N An Outline of Metallurgy New York:
Hart, 1969
See also: Alloys; Aluminum; Brass; Copper; Iron;
Manganese; Nickel; Oxides; Steel; Tin
Buildings and appliances,
energy-efficient
Category: Environment, conservation, and
resource management
Before the 1970’s, buildings and appliances were
de-signed without thought to efficient energy usage or
their environmental impact Then came a growing awareness that the burning of fossil fuels for energy re-leases gases that pollute the environment, causes acid rain, and contributes to global warming Environ-mental and health concerns and energy costs led to the increased development of renewable, or “clean energy,” resources: solar, wind, hydro, geothermal, and bio-mass Movements toward “green buildings,” energy management systems (EMS’s), and intelligent control systems developed.
Background
In 1990, the energy used in American buildings for heating, cooling, lighting, and operating appliances amounted to roughly 36 percent of U.S energy use and cost nearly $200 billion About two-thirds of this amount was fuel energy, including the fuel energy lost
in generating and delivering electricity Electricity is considered worth the extra cost because it is quiet, convenient, and available in small units Because of continuing improvements in space conditioning, pliances, and the controls for both, building and ap-pliance energy use could be cut by half or even three-quarters
Insulation
“Space conditioning” is the warming and cooling of rooms and buildings Ways to make it more efficient include improving insulation, siting, heat storage, heaters, and coolers Structures gain and lose heat in three ways: air movement, conduction, and radiation Insulating a building requires isolating it from these processes The most important consideration is re-ducing a building’s air flow, and walls and ceilings are the primary reducers The space-conditioning load of
a structure may be construed as the number of “air changes” per hour The next level of consideration is heat conduction through walls, windows, ceilings, and floors Heat conduction can be slowed by con-structing a building with thicker walls or by using insu-lating materials that conduct heat more slowly A ma-terial’s insulating ability is measured by its resistance
to conduction, called its R value A major innovation during the 1970’s was the practice of framing houses with 5-by-15-centimeter (2-by-6-inch) studs instead of the standard two-by-fours That design allowed insula-tion to be 50 percent thicker
Windows are a major heat conductor One window can conduct as much heat as an entire wall During the 1980’s in the United States, the amount of heat
Trang 8lost through windows was estimated to have equaled
half the energy that was obtained from Alaskan oil
fields Double-paned and even triple-paned windows
(with air space between the panes) to reduce this loss
became more common To reduce conduction
fur-ther, the air between panes can be partially evacuated,
or the space can be filled with a less conductive gas,
such as xenon Finally, windows can also have coatings
that reflect infrared (heat) radiation, thereby keeping
summer heat out and holding heat inside during
winter
Beginning in the 1970’s, Canadian researchers
worked to develop “superinsulated” houses:
struc-tures so well insulated that they hardly required
fur-naces, even in the severe winter climates
characteris-tic of much of Canada The costs were an additional
two thousand to seven thousand dollars in
construc-tion and an ongoing expense of running an air
exchanger In the winter, the exchanger warms
in-coming fresh air with the heat from air being
ex-hausted; in the summer it cools incoming air Because
such a building is so well sealed, without the air
exchanger one could smell yesterday’s bacon and
cof-fee (as well as more noxious lingering odors)
Siting
The importance of the siting of a structure—that is,
the direction it “faces,” including where windows and
doors are placed and where there are solid walls—has
been known since ancient times In the developed
na-tions of the twentieth century, as energy sources
be-came widely and cheaply available, designers and
ar-chitects often ignored this aspect of building design
For example, they often did not consider the
impor-tance of catching sunlight on south-facing sides,
pro-tection from the cold on the north side, hardwood
trees (which can supply summer shade and then drop
their leaves to allow more sunlight to pass through in
winter), and overhangs to shade against the high
sum-mer Sun These design elements alone can reduce the
need for heating and cooling energy significantly
The energy crises of 1973 and 1979 reminded
builders of the drawbacks of old, energy-intensive
ap-proaches to building design and led to renewed
con-sideration of natural heat flow The awareness that oil
is a limited resource also gave credence to a more
radi-cal siting idea known as terratecture: A structure can
be made more energy-efficient by locating it partially
underground Terratecture is particularly efficient
when used to shield a north-facing wall Insulation
and thermal inertia reduce heating and cooling loads, while windows facing south and opening into court-yards allow as much window space as conventional structures For a slight increase in construction costs, terratectural houses have significant energy advan-tages, allow more vegetation, and require less mainte-nance They are quite different from conventional houses, however, and have not been widely adapted
Heating and Cooling During the mid-1700’s, the British colonies in North America faced an energy crisis: a declining amount of firewood Traditional large fireplaces sent most heat
up the chimney Benjamin Franklin studied more effi-cient fireplaces in Europe, and he invented a metal stove that radiated more of the fire’s heat into the room The Franklin stove (1742) provided more heat
by increasing “end-use efficiency” rather than by in-creasing energy use Two hundred years later, the en-ergy crises of the late twentieth century led to the application of burner advances that had been devel-oped or proposed earlier Studies of flame dynamics and catalysts led to more complete fuel combustion, and better radiators captured more heat from the burner
Hot climates and commercial buildings that pro-duce excess heat require air-conditioning Air-condi-tioning is based on heat pumping, which cools the hot internal air by moving the heat elsewhere Most heat pumps compress a gas on the hot side and allow it to decompress on the cold side
Electronic controls have helped reduce energy waste in space conditioning For instance, in winter, computerized thermostats can maintain lower tem-peratures while people are not in a building and then automatically change the settings to a higher, more comfortable level at times when people are scheduled
to return For gas appliances, the replacement of pilot lights with electric igniters has helped reduce unnec-essary fuel use (Electric igniters are even more im-portant for intermittently used burners, such as those used in stoves.)
Another way of decreasing energy input is storing heat or cold from different times of the day, or even different seasons of the year Thick stone on walls and floors, such as those made of adobe bricks in the Southwest, have been used for centuries in desert cli-mates; they remain relatively cool during the after-noon heat and then slowly give off the day’s heat dur-ing cold nights Higher-technology variants of storage
Trang 9use less material per unit of heat Office complexes
that are designed to store cool air can use smaller
air-conditioners and cheaper, off-peak power
Lighting and Motors
Until the mid-nineteenth century, people rose at dawn
and retired at sundown because there was no form of
artificial lighting that could provide sufficient light
for most work or leisure activities after dark
Im-proved oil lamps and then incandescent electric lights
(first widely marketed by Thomas Edison in 1879)
started a revolution that eventually consumed roughly
a quarter of U.S electricity directly and, in addition,
contributed to building cooling loads
Incandescent lights use resistance heating to make
a wire filament glow, so they generate significant heat
in addition to light Fluorescent lights, with a glow of
current flowing through gases under partial vacuum,
are more efficient and last longer Fluorescent
light-ing was invented in 1867 by Antoine-Edmond
Becque-rel but not widely marketed until the 1940’s In the
1980’s, compact fluorescents for small lamps were
de-veloped, followed by light-emitting diode technology;
such low-energy forms of lighting have begun to
sup-plant incandescent lighting, especially in new
build-ing projects Moreover, controllers can improve
effi-ciency by switching off lights when people are gone;
they can also be programmed to reduce lighting when
sunlight is available
Electric motors range from tiny shaver motors to
power drives for elevators and large air conditioners
A number of methods have been developed to make
motors more efficient The use of additional motor
windings (costing more copper wire) has always been
an option Electronic controls that match power used
to the actual load rather than based on a constant
high load were developed after the 1970’s energy
cri-ses Amorphous metals (produced by rapid cooling
from the molten state) have been developed to allow
electromagnets in motors to switch off faster,
reduc-ing drag; they also make more efficient transformers
for fluorescent lights
Most improvements to appliance efficiency involve
some combination of better motors and better space
conditioning The electrical loads from refrigerators—
among the largest in most homes in industrialized
nations—dropped by half in average energy demand
in the United States between 1972 and 1992 More
efficient motors and better insulation were
responsi-ble for the improvement
The Energy Star Program
In 1992, the U.S Environmental Protection Agency established Energy Star, a voluntary labeling program that identifies products meeting strict standards of energy efficiency The program set the standard for commercial buildings, homes, heating and cooling devices, major appliances, and other products The Energy Star concept eventually expanded to other countries, including members of the European Union, Japan, Taiwan, Canada, China, Australia, South Af-rica, and New Zealand
In 1992, the first labeled product line included per-sonal computers and monitors In 1995, the label was expanded to include residential heating and cooling products, including central air conditioners, furnaces, programmable thermostats, and air-source heat pumps Energy Star for buildings and qualified new homes was also launched In 1996, the U.S Depart-ment of Energy became a partner in the program, and the label expanded to include insulation and appli-ances, such as dishwashers, refrigerators, and room air conditioners By March, 2006, Americans had pur-chased more than two billion products that qualified for the Energy Star rating, and by December of that year, there were almost 750,000 Energy Star qualified homes nationally
In 2008, energy cost savings to consumers, busi-nesses, and organizations totaled approximately $19 billion The average house can produce twice the greenhouse-gas emissions as the average car The amount of energy saved in 2008 helped prevent greenhouse-gas emissions equal to those from 29 mil-lion cars By 2009, Energy Star had partnerships with more than 15,000 public and private sector organiza-tions, and had labels on more than sixty product cate-gories, including thousands of models for home and office use
Compared to conventional products, those ap-proved by Energy Star are more energy-efficient, save
on costs, and feature the latest technology By using less energy, they help reduce the negative impact on the environment
In the average home, heating and cooling are the largest energy expenditures, accounting for about one-half of the total energy bill Energy Star compli-ant heating and cooling equipment can cut yearly en-ergy bills by 30 percent, or more than six hundred dol-lars per year A qualified furnace, when properly sized and installed, along with sealed ducts and a program-mable thermostat, uses about 15 percent less energy
Trang 10than a standard model and saves up to 20 percent on
heating bills An Energy Star room air conditioner
use at least 10 percent less energy than conventional
models, and they often include timers for better
tem-perature control To keep heating, ventilating, and
air-conditioning (HVAC) systems running efficiently,
Energy Star recommends changing air filters
regu-larly, installing a programmable thermostat, and
seal-ing heatseal-ing and coolseal-ing ducts
The second largest energy expenditure is water
heating, which costs the typical household four
hun-dred to six hunhun-dred dollars per year A new Energy
Star water heater would cut water heating bills by half
Energy Star refrigerators use 20 percent less energy
than other models, thus cutting energy bills by $165
over its lifetime They also have precise temperature
controls and advanced food compartments to keep
food fresher for a longer time Because they use much
less water than conventional models, Energy Star
dishwashers help ease the demand on the country’s
water supplies Energy Star also recommends
run-ning the dishwasher with a full load and that the
air-dry option be used instead of the heat-air-dry
Using the most innovative technology, Energy Star
clothes washers cut energy and water consumption by
more than 40 percent, compared to conventional
models Most do not have a central agitator and use a
reduced amount of hot water in the wash cycle
In-stead of rubbing laundry against an agitator in a full
tub, front-load washers tumble laundry through a
small amount of water Modern top loaders flip or
spin clothes through a reduced stream of water
So-phisticated motors spin clothes two to three times
faster during the spin cycle to extract more water, thus
requiring less time in the dryer
Lighting accounts for 20 percent of the electric bill
in the average U.S home, and 7 percent of all energy
consumed in the United States is used in lighting for
homes and businesses An Energy Star qualified
com-pact fluorescent light bulb (CFL) uses 75 percent less
energy and lasts ten times longer than an
incandes-cent bulb It pays for itself in six months, and the
sav-ings are about thirty dollars over its lifetime
The Green Building Movement
After the rise of environmental consciousness in the
1960’s, and the 1973 and 1979 oil shortages,
con-cerned groups around the world began to look for ways
to conserve energy and preserve natural resources
One of the most important applications for this
cul-tural shift was the transformation of human dwell-ings and workplaces, resulting in the green building movement Starting with heat from the Sun, archi-tects incorporated active photovoltaic systems and passive designs that cleverly positioned windows, walls, and rooftops to capture and retain heat Another fac-tor was an increased attention to heat exchange as affected by materials and construction techniques Building materials were also reexamined in terms of toxicity; pollution and energy consumption in factory processing; durability; interaction with soil, bedrock, water; and other factors
Contemporary green building looks at all of these issues and more, because a narrow approach could actually do more harm than good A building sealed too tightly, for example, could have excellent heat retention, but might not have enough internal air circulation Recycled materials might lower resource consumption, but could actually be more toxic Therefore cross-disciplinary collaboration is neces-sary in order to achieve effective green building de-sign In the United States, the Office of the Federal Environmental Executive (OFEE) recognizes the complexity of green building, and organizes the ef-fort around two primary goals: limiting the consump-tion of basic resources such as materials, water, and energy and protecting the environment and people’s health
One of the most important elements in a green building is its use of green energy Although some governments have established precise technical defi-nitions of green energy for purposes of incentive pro-grams, the term is generally associated with environ-mentalism; conveys the idea of safe, nonpolluting energy; and often means renewable energy Although not all consumers are able to construct a new green building, many achieve these goals by transforming existing structures A key element in both new and existing buildings is the use of Energy Star compliant appliances
Renewable Energy Sources The energy crises of the 1970’s and environmental concerns led to interest in alternative, renewable en-ergy resources Renewable enen-ergy is “clean” enen-ergy from a source that is inexhaustible and easily replen-ished Nonrenewable energy comes from sources not easily replaced, such as fossil fuels and nuclear energy Renewable energy does not pollute air or require waste cleanups like nonrenewable energy generation