General
Information
General
Benefits of Renewable Energy
The main environmental benefit of renewable resources is that
when they are used, they can displace or avoid the use of fossil
fuels and nuclear power.
Eighty-five
percent of the energy we use in the US comes from nonrenewable
"fossil" fuels such as coal, oil, and natural gas. Supplies
of these fuels will diminish over time and become more expensive
to use. (The US now imports nearly 65% of the crude oil it consumes,
which is a serious national security issue.) The mining, processing,
transportation, and conversion of fossil fuels to energy have
many environmental impacts. Many scientists believe that the carbon
dioxide (CO2) and other gases released by burning fossil fuels
contribute to the "greenhouse" effect, which may cause
global climate change. Burning fossil fuels also results in the
emission or formation of carbon monoxide (CO), sulfur dioxide
(SO2), nitrogen oxides (NOx), Volatile Organic Compounds (VOC),
particulate matter (PM), and heavy metals such as lead and mercury.
All of these have negative impacts on the environment and human
health. SO2 causes acid rain, and CO and NOx contribute to ground
level ozone. PM results in hazy conditions in cites and scenic
areas, and, along with ozone, contributes to asthma, difficult
or painful breathing, and chronic bronchitis, especially in children
and the elderly. Fine particulate matter is also thought to cause
lung cancer. Thousands of barrels of oil spill or leak every year
while being transported on ships, trains, and trucks, and in pipelines.
The
following are estimates of the amounts of CO2 and air pollutants
released into the air (in 2001 and 1999) as a result of the combustion
of fossil fuels:
Carbon
Dioxide Emissions In 2001, By Source (in millions of tons)
Electric Power Plants (coal, natural gas, oil): 2,500
Vehicles (gasoline, diesel, etc): 2,000
Residential Heating (fuel oil and gas): 410
Commercial Buildings (fuel oil and gas): 240
______________________________________________________________________
(Data source: Electric Power Annual 2001: Volume II, Energy Information
Administration; Table 5.1. Emissions, 1990 through 2001, see bibliography
below.)
Air
Pollutant Emissions In 1999, By Source (in millions of tons):
SO2 / NOx / PM / VOC / CO
Electric
Power Plants (coal, natural gas, oil): 12.7 / 5.7 / 0.35 / 0.06
/ 0.45
Vehicles (gasoline, diesel, etc): 1.3 / 14 / 1.4 / 8.53 75
Residential Heating (fuel oil and gas): 0.1 / 0.72 / 0.04 / 0.03
/ 0.25
Commercial Buildings (fuel oil and gas): 0.26 / 0.35 / 0.03 0.03
/ 0.14
______________________________________________________________________
(Data source: National Air Quality and Emissions Trends Report,
1999, US Environmental Protection Agency, see bibliography below)
Nuclear
power plants do not release carbon dioxide and air pollutants.
However, accidental releases of small amounts of radioactive materials
do occur, and the release of large amounts of radioactive materials
due to a major plant malfunction can have disastrous consequences.
The meltdown of the Chernobyl nuclear reactor in Ukraine is an
example of this. Also, controlling the nuclear reaction, and producing,
handling, transporting, storing, and disposing of radioactive
fuels, materials, and waste requires highly complex and expensive
procedures. Safeguarding nuclear fuel and waste requires an expensive
and long-term commitment for present and future generations. Thousands
of tons of spent, but still radioactive nuclear fuel, are being
stored at nuclear power plants around the country. Every kilowatt-hour
of electricity produced at nuclear reactors results in more spent
fuel that has to be stored and eventually transported on highways
and railroads to a disposal facility.
The following
are emission factors for air pollutants that are released from
fossil fuel power plants to produce a kilowatt-hour (kWh) of electricity
from different fuels, for heating fuels, and for gasoline. These
are also the amounts of pollutants that are avoided if the electricity
or fuel is produced from a renewable resource (or not used at
all through energy conservation and efficiency).
Air
Pollutants and Emission Factors for Electricity Generation in
Pounds per kWh by Fuel Type
Eastern Coal / Western Coal / Gas / Oil
Sulfur
Dioxide (SO2): 0.0006 / 0.65 / 0.01
Nitrous Oxides (NOx): 0.09 / 0.15 / 0.08
Particulates (PM10): 0.01 / 0.02 / 0.8
VOCs: 0.007 / 0.006 / 0.78
Carbon Dioxide (CO2): 126 / 167 / 130
______________________________________________________________________
(From data in the Renewable Energy Annual 1995 (1996), and Carbon
Dioxide Emissions from the Generation of Electric Power in the
United States, (2000) Energy Information Administration. This
does not include the many other gaseous, solid, and liquid wastes
and pollutants including acids and heavy metals (such as mercury)
that are released by coal burning power plants.)
Air
Pollutants and Emission Factors for Heating Fuels in Pounds per
Million Btu in Fuel
Gas / Fuel Oil / Wood *
Sulfur
Dioxide (SO2): 0.0006 / 0.65 / 0.01
Nitrous Oxides (NOx): 0.09 / 0.15 / 0.08
Particulates (PM10): 0.01 / 0.02 / 0.8
VOCs: 0.007 / 0.006 / 0.78
Carbon Dioxide (CO2): 126 / 167 / 130
______________________________________________________________________
(From "Heating Fuel Choices," Environmental Building
News (see bibliography below)
* For average wood burning appliance. Note, there is no net gain
in CO2 emissions from wood burning, if the wood is harvested on
a sustainable basis.
There are approximately 140,000 Btu/gallon (9,320 kilocalories/liter)
of fuel oil; 1,025,000 Btu/thousand cubic feet (7,336 kilocalories/cubic
meter) in natural gas; 20,000,000 Btu in a chord of wood, and
3,412 Btu (860 kilocalories) in a kWh of electricity.
Air
Pollutants and Emission Factors for Gasoline in Pounds per Gallon
Hydrocarbons: 0.13
CO: 1
NOx: 0.07
CO2: 19.7
______________________________________________________________________
(From: Emission Facts, US Environmental Protection Agency, on
the Web at: www.epa.gov/otaq/consumer/f00013.htm)
General
Impacts of Renewables
The greatest environmental impacts of nearly all renewable energy
technologies stem from the production of the materials and the
energy necessary to produce the structures that convert renewable
resources to energy, and the energy and surface (or land) area
required for their installation and operation. These impacts derive
from the basic nature of renewable energy resources: they are
diffuse, and so require relatively large structures to capture
(or store) and convert the resource to energy. For example, hydroelectric
dams require concrete and steel, and the resulting reservoir may
flood a large basin. The mining and production of the minerals
in metals and concrete have environmental impacts. Metals and
concrete also take a lot of energy to produce. If this energy
comes from fossil fuels, the impacts associated with these fuels
are applicable to renewable energy installations.
How the
material, energy, and land area requirements of renewable energy
systems compare to those for fossil fuel or nuclear power systems
is difficult to assess. As with any energy technology, the larger
the "power plant," the greater the site-specific environmental
impact. Since they can be placed on existing structures, small-scale
installations of renewable energy technologies, such as residential
solar electric or water heating systems, have practically no environmental
impacts once installed. Many studies have been done on these issues,
and the results vary widely, depending on the assumptions and
data used by the researchers. Several of the publications in the
bibliography below are useful references for research on this
topic. The following is a discussion of the specific impacts of
each type of renewable energy technology in the order of their
relative contributions to the U.S. energy supply.
Credit
note: The above information was copied from the U.S Department
of Energy web site, www.eere.energy.gov
Additional
Information on Renewable Energy
The
sun is a fusion reactor (unlike nuclear power which creates energy
from splitting atoms - fission) delivering 1.52 x 10 to the 18th
power kWh/year to earth. All mankind's energy needs total less
than 0.1% of this amount.
Enough
sunlight falls on the Earth's surface each minute to meet world
energy demand for an entire year.
An
average household uses 700 kWh each month or about 8500 kWh each
year.(1)
Traditional
Energy
Percentages
of United States energy consumption, 1990(4) and 1992(5) by energy
source:
| |
1990 |
1992 |
| Oil |
39.7% |
39.4% |
| Natural Gas |
22.7% |
23.6% |
| Coal |
22.4% |
22.1% |
| Renewable |
7.9% |
6.9% |
| Nuclear |
7.3% |
7.7% |
Fossil
fuels like coal, oil and natural gas are being depleted at a rate
that is 100,000 times faster than they are being formed. (3)
Oil currently
provides more than 40% of the nation's primary energy and 97%
of its transportation energy. (3)
Most electricity
is currently produced by burning coal, oil or natural gas to make
steam which in turn is forced through a turbine generator producing
electricity. (1)
Approximately
35 % of all United States' energy needs are supplied by electrical
power. About two thirds of this electricity is used in residential
and commercial buildings and about one third is for industrial
processes. (8)
Buildings
consume about 36% of all primary energy (excluding transportation)
produced in the United States and two thirds of all electricity
generated. (8)
If California
was a nation on its own, it would be the worlds fourth largest
consumer of energy. (1992) (11)
Japan
imports 70% of its energy from the Middle East. (11)
Renewable
Energy Technologies
Renewable
energy includes those forms of energy that we cannot deplete or
that are quick to regenerate and include solar, wind, geothermal,
hydro, biofuels, ocean energy, and hydrogen power. (1)
Renewables
accounted for 11% of total domestic electricity generation in
1994. (1)
In 1994,
renewables supplied 18% of energy demand worldwide and approximately
8% in the United States (mostly hydro electric). (1)
Solar
power ranging from the heat of each day to solar electric conversion
technologies comes directly from the sun's rays. We typically
include Solar Electric (Photovoltaic), Solar Thermal, and Solar
Heating, Cooling and Lighting (Active and Passive) in this category.
(1)
Wind power
is the result of uneven warming of our atmosphere, thanks to the
sun, causing rising
PHOTOVOLTAICS
Overview
Solar
Electric or Photovoltaic Systems convert some of the energy in
sunlight directly into electricity. Photovoltaic (PV) cells are
made primarily of silicon, the second most abundant element in
the earth's crust, and the same semiconductor material used for
computers. When the silicon is combined with one or more other
materials, it exhibits unique electrical properties in the presence
of sunlight. Electrons are excited by the light and move through
the silicon. This is known as the photovoltaic effect and results
in direct current (DC) electricity. PV modules have no moving
parts, are virtually maintenance-free, and have a working life
of 20 - 30 years.
There
are three basic categories of photovoltaic systems with several
types in each category.
Crystalline
silicon Flat Plate collectors are the most developed and prevalent
type in use today. These include single crystal silicon and polycrystalline
silicon which is either grown or cast from molten silicon and
later sliced into its cell size. They are then assembled onto
a flat surface; no lenses are used.
Thin Film systems are inherently cheaper to produce than
crystalline silicon but are not as efficient. They are produced
by depositing a thin layer of photovoltaic material to a substrate
like glass or metal. This group includes amorphous silicon like
the kind found in calculators and watches.
Concentrators use much less of a specialized photovoltaic
material and employ a lens or reflectors to concentrate sunlight
on the photovoltaic cell and increase its output. They can be
produced more cheaply than either of the other type due to the
reduced amount of expensive PV material. But they can only use
direct sun, so they must track the sun precisely and do not work
when it is cloudy.
Photovoltaic
System Terms
PV System
terms progress from small to large as follows:
PV
cells, the smallest unit of a PV system, are wired together
to form modules.
Modules
are usually a sealed, or encapsulated, unit of convenient size
for handling.
Arrays.
Modules are wired together to form panels.
Groups of panels form arrays.
Array
Field. A number of arrays form an array field.
The total
system includes the arrays and any other equipment like charge
controllers, storage (batteries) and tracking and monitoring equipment,
collectively called balance of system (BOS) components.
History
The history
of PV's dates back to 1839 and major developments evolved as follows:
1839 Edmund
Becquerel, a French physicist observed the photovoltaic effect.
1880's
Selenium PV cells were built that converted light in the visible
spectrum into electricity and were 1% to 2% efficient. Light sensors
for cameras are still made from selenium today.
In the
early 1950's the Czochralski meter was developed for producing
highly pure crystalline silicon.
In 1954
Bell Telephone Laboratories produced a silicon PV cell with a
4% efficiency and later achieved 11% efficiency.
In 1958 the US Vanguard space satellite used a small (less than
one watt) array to power its radio. The space program has played
an important role in the development of PV's ever since.
During
the 1973-74 oil embargo the US Department of Energy funded the
Federal Photovoltaic Utilization Program, resulting in the installation
and testing of over 3,100 PV systems, many of which are in operation
today.
The 1970s
through the 1990s have seen a relative disinterest in solar power
with majority ownership of many United States PV manufacturers
transferring to German and Japanese interests.
The Gulf
war of 1990 again sparked Americas interest in non-fossil fuel
energy alternatives.
International
markets for solar take off in the mid 1990s.
Glossary
of Solar and Photovoltaic Terms (1)
Cell
efficiency - The ratio of the electrical energy produced by
a photovoltaic cell (under full sun conditions or 1 kW/m2) to
the energy from sunlight falling upon the cell.
Charge
controller - A component that controls the flow of current
to and from the battery subsystem to protect the batteries from
overcharge and over discharge. The charge controller may also
monitor system performance and provide system protection.
Diffuse
radiation - Sunlight received indirectly as a result of scattering
due to clouds, fog, haze, dust or other substances in the atmosphere.
Direct
radiation - Light that has traveled in a straight path from
the sun (also referred to as beam radiation). An object in the
path of direct radiation casts a shadow on a clear day.
Flat-plate
array - A photovoltaic array in which the incident solar radiation
strikes a flat surface and no concentration of sunlight is involved.
Fresnel
Lens - A concentrating lens, positioned above and concave
to a PV material to concentrate light on the material.
Grid-connected
- An energy producing system connected to the utility transmission
grid. (Also called utility interactive.)
Hybrid
system - A power system consisting of two or more power generating
subsystems (e.g., the combination of a wind turbine and a photovoltaic
system).
Insolation
- The amount of sunlight reaching an area, usually expressed
in watts per square meter per day.
Load
- Electrical power being consumed at any given moment. The
load that an electric generating system supplies varies greatly
with time of day and to some extent season of year. Also, in an
electrical circuit, the load is any device or appliance that is
using power.
Parallel
connected - A method of connection in which positive terminals
are connected together and negative terminals are connected together.
Current output adds and voltage remains the same. (See also series
connected.)
Photovoltaic
cell - The semiconductor device that converts light into dc
electricity. The building block of photovoltaic modules.
Series
connected - A method of connection in which the positive terminal
of one device is connected to the negative terminal of another.
The voltages add and the current is limited to the least of any
device in the string. (See also parallel connected.)
Solar
constant - The rate at which energy is received from the sun
just outside the earth's atmosphere on a surface perpendicular
to the sun's rays. Approximately equal to 1.36 kW/m2.
Thick
cells - Conventional cells, such as crystalline silicon cells,
which are typically from 4 to 17 mils thick. In contrast, thin-film
cells are several microns thick.
Thin-film
cells - Photovoltaic cells made from a number of layers of
photo-sensitive materials. These layers are typically applied
using a chemical vapor deposition process in the presence of an
electric field.
Voltage
regulator - A device that controls the operating voltage of
a photovoltaic array.
Resources:
(1) Adapted from Solarex Corporation, Frederick, MD
All the
above was resoursed from American Solar Energy Societies web site,
www.ases.org, 2003
WIND
Overview
Wind turbines
are moved by the wind and convert this kinetic energy directly
into electricity by spinning a generator. They use air foils or
blades like the wing of an airplane to turn a central hub which
is connected through a series of gears (transmission) to an electrical
generator. The generator technology is identical to that employed
by our traditional fossil fuel generating plants. Wind turbines
come in two basic configurations:
Horizontal
Axis Turbines (HATs) are the most common type seen sitting on
top of towers with two or three blades. The orientation of the
drive shaft, the part of the turbine connecting the blades to
the generator, is what decides the axis of a machine. Horizontal
axis turbines have a horizontal drive shaft. The blades may be
facing into the wind, upwind turbine, or the wind may hit the
supporting tower first, downwind turbine.
Vertical Axis Turbines (VATs) have vertical drive shafts. The
blades are long, curved and attached to the tower at the top and
bottom. Flowind is the most noted manufacturer of Vertical Axis
Turbines.
History
The use of wind energy dates back to the dawn of civilization
when sailing vessels were powered by the wind. Wind energy was
put to use on land in the following steps:
Windmills,
said to be invented in China, were reportedly used in Persia around
200 BC.
In the
14th century, the Dutch improved on the design that had spread
throughout the Middle East and continued to use it for its primary
purpose of grinding grain.
A wind
powered water pump was introduced in the United States in 1854.
It was the familiar fan type with many vanes around a wheel and
a tail to keep it pointed into the wind. By 1940, over 6 million
of these windmills were being used in the United States mainly
for pumping water and generating electricity.
The Danish
pioneered the generation of electricity with wind power in 1890
through a program which resulted in 120 five to twenty-five kilowatt
wind-powered systems being put into operation.
In 1941,
a 1.25 megawatt machine was hooked to the Central Vermont Public
Service grid near Rutland, Vermont.
Denmark
hooked a 200 kW turbine to the utility grid in 1942.
The oil
embargo of 1973 led to many government sponsored wind turbine
development programs in the United States. Westinghouse Electric
received a DOE/NASA contract to develop first generation 200 kW
wind turbines, known as MOD-OAs. The largest of this series and
the largest in the world, the 3.2 megawatt MOD-5B is operating
in Oahu, HI.
The Public
Utilities Regulatory Policies Act (PURPA) of 1978 and a 25 % tax
credit for investors in turbines jump started commercial development
of the United States wind industry and resulted in 6,870 turbines
being installed in California between 1981 and 1984. The tax credits
expired on Dec. 31, 1985.
The cost
of wind power continued to decline through advancements in design,
siting practices and the cost of capital from around 14 cents
per kWh in 1986 to below 5 cents per kWh in 1994. Wind power is
now cost-competitive in many electric power applications and is
experiencing rapidly growing deployment.
Resources:
Hermann, Henery, WR Lazard, Laidlaw and Mead, Inc., "The
Wind Power Industry," November, 1994.
Wind
System Components
The following
components are arranged from the top down starting at the wind/turbine
interface. (1)
Blades
- Blades are the part of a turbine that capture the wind.
Advanced designs have led to higher energy capture. Two or three
blades most often make up a rotor. Blades are made from fiber
glass, polyester, or epoxy resins. Some have wood cores. Blade
diameters for commercial size turbines range from 25 to 50 meters
and can weigh over 2000 pounds each.
Rotor
- The rotor is all the blades and the center hub which the blades
are attached to. The hub is attached to the drive shaft (or it's
attached directly to a large gear in some systems). Upwind machines
have their rotor in front of the tower (wind hits the rotor before
the tower). Downwind machines are just the reverse arrangement.
Transmission
- Power is transferred through the spinning drive shaft to
a series of gears, or transmission, that increase the low 60 RPMs
of the blade to between 1,500 and 2,000 RPMs.
Generator
- The high RPM output from the transmission is then connected
to an electric generator that produces electricity from motion
like the ones used by traditional heat/steam systems.
Controls
- Several control systems are all coordinated and monitored by
a computer and can be accessed from a remote location. Pitch controls
twist the blades to improve performance at different wind speeds.
Yaw controls point the whole turbine into the wind. Electronic
controls keep the same voltage flowing from the generator as it
changes speed. This variable speed generator is an important part
of making wind turbines cost effective.
Nacelle
- Simply the casing which houses the turbine components. Usually
fiberglass, the nacelle protects components and offers a platform
to perform maintenance form.
Tower
- Towers are typically one of two types; the "monotube"
or solid steel tube or the "Truss" type which looks
like an erector set. Heights vary with rotor size between about
80 and 150 feet.
Resources:
(1) Kenetech sales literature.
All the above was resoursed from American Solar Energy Societies
web site, www.ases.org, 2003
SOLAR THERMAL
Overview
Solar
Thermal Systems concentrate heat and transfer it to a fluid. The
heat is then used to warm buildings, heat water, generate electricity,
dry crops or destroy dangerous waste. Solar Thermal Collectors
are divided into three categories:
Low-temperature
collectors provide low grade heat, less than 110 Fahrenheit, through
either metallic or nonmetallic absorbers for applications such
as swimming pool heating and low-grade water and space heating.
Medium-temperature collectors provide medium to high-grade heat
(greater than 110 Fahrenheit, usually 140 to 180 Fahrenheit),
either through glazed flat-plate collectors using air or liquid
as the heat transfer medium or through concentrator collectors
that concentrate the heat to levels greater than "one sun."
These include evacuated tube collectors, and are most commonly
used for residential hot water heating.
High-temperature collectors are parabolic dish or trough collectors
primarily used by independent power producers to generate electricity
for the electric grid. (1)
Concentrating
Solar Thermal Systems use three different types of concentrators:
Central
receiver systems use heliostats (highly reflective mirrors)
that track the sun and focus it on a central receiver.
Parabolic dish systems use dish-shaped reflectors to concentrate
sunlight on a receiver mounted above the dish at its focal point.
Parabolic trough systems use parabolic reflectors in a
trough configuration to focus sunlight on a tube running the length
of the trough.
Technology
Examples
Pool
Heating - These systems can be as simple as water running
through a black hose and specially manufactured systems are more
efficient modifications on this concept.
Domestic
Hot Water - These are what you are most likely seeing on all
those houses where you live. They come in a variety of styles
but all of them collect heat in some liquid, usually water or
water mixed with an anti-freeze, that runs through pipes in a
box with glass on the front. The box helps keep temperatures inside
around the pipes higher so more heat transfers to the liquid.
The hot liquid gives its heat to another loop of pipes through
a heat exchanger and this new loop is used for home hot water
use or heating the space with a radiator.
Commercial
Scale - These can be designed to heat or cool a large commercial
space or to make steam which can turn a turbine to make electricity.
The Luz system and Solar Two are two examples of commercial, solar-thermal-electric
systems operating today. See Solar Thermal in the BUSINESS BRIEFS
AND PROJECTS section.
History
Solar
heating for water and other applications was around long before
fossil fuels dominated our energy paradigm. In fact, solar power
has been and always will remain an excellent energy option, long
after the momentary fossil fuel model fades into smoke. (1)
In 1767,
the Swiss scientist Horace de Saussure was credited with building
the world's first solar collector, later used by Sir John Herschel
to cook food during his South Africa expedition in the 1830's.
The father
of solar energy in the United States is Baltimore inventor Clarence
Kemp, who, in 1891, patented the first commercial solar water
heater.
In 1895,
two Pasadena, California executives bought the rights to Kemp's
solar system, and, with the help of high gas and coal prices,
fitted 30% of the homes in Pasadena with solar water heating systems
by 1897.
Solar
technology advanced to roughly it's present design in 1908 when
William J. Bailey of the Carnegie Steel Company, invented a collector
with an insulated box and copper coils.
Bailey
sold 4,000 units by the end of W.W.I and a Florida businessperson
who bought the patent rights sold nearly 60,000 units by 1941.
The rationing
of copper during W.W.II sent the solar water heating market into
a sharp decline.
In the
60's, a handful of United States companies were manufacturing
solar water heaters, but when President Richard Nixon allowed
the amount of imported oil to pass 50%, the cheap oil held down
the solar market.
During
the 1970's, in response to the OPEC oil embargo, a number of federal
and state incentives were established to promote solar energy.
President Jimmy Carter put solar water heating panels on the White
House.
In 1974,
FAFCO, a California company specializing in solar pool heating
and Solaron, a Colorado company which specialized in solar space
and water heating, became the first national solar manufacturers
in the United States.
Incentives
helped create the 150 business manufacturing industry for solar
systems with more than $800 million in annual sales by 1985.
Tax credits
and incentives have mostly disappeared but today's industry (1995)
represents the few strong survivors and more than 1.2 million
buildings in the United States have solar water heating systems,
and there are 250,000 solar heated swimming pools.
Resources:
(1) Sklar, Scott, and Sheinkopf, Consumer Guide to Solar Energy,
Bonus Books, Inc., 1995. p. 7-18.
All the above was resoursed from American Solar Energy Societies
web site, www.ases.org, 2003
SOLAR BUILDINGS
Overview
and Components
Passive
solar, or climate responsive buildings use existing technologies,
techniques and materials to heat, cool and light buildings. They
coordinate traditional building elements like insulation, south-facing
glass, and massive floors with the climate to achieve sustainable
results. These beautiful, comfortable and healthy living spaces
can be built for no extra cost while increasing affordability
through lower utility payments. They also keep investment dollars
in the local building industry rather than transferring them to
short term energy imports. Passive solar buildings are better
for the environment while contributing to an energy independent,
sustainable energy future.
Advances
in glass technology have perhaps been the single largest contributor
to building efficiency since the 1970s and they play an important
roll in solar design. Some window advances include:
Double
and triple pane windows with much higher insulating values.
Low emissivity
or Low-E glass employing a coating which lets heat in but not
out.
Argon
(and other) gas filled windows that increase insulating values
above windows with just air.
Phase-change
technologies that can switch from opaque to translucent when a
voltage is applied to them.
Building
Integrated Photovoltaics (BIPV) continue a steady advance on the
building market as the price for PV's drops. A BIPV takes advantage
of the cost savings of a dual role by serving as a functioning
part of the structure as well as an electricity producing element.
Integrated designs include; roofing shingles and tiles, semi-transparent
curtain walls and skylights, awnings, and entire roofing systems.
While
not directly related to renewable energy generation technologies,
energy efficiency plays an important role in the resource use
in buildings. This multi-billion dollar annual industry includes
such things as:
High performance
window, or glazing, installation.
Lighting
retrofits with more efficient lamps.
Heating
Ventilating and Air Conditioning (HVAC) system upgrades using
more efficient motors, fans and compressors.
Building
envelope insulation and weatherizing.
Heat recovery
systems that recapture the heat in exhaust air.
History
Building
design has historically borrowed its inspiration from the local
environment and available building materials. More recently, humankind
has designed itself out of nature, taking a path of dominance
and control which led to one style of building for nearly any
situation. Like the ancient people, we can maintain our personal
and planetary health through designing with nature. (2)
In 100
A.D., Pliny the Younger, a historical writer, built a summer home
in Northern Italy featuring thin sheets of mica windows on one
room. The room got hotter than the others and saved on short supplies
of wood.
The famous
Roman bath houses in the first to fourth centuries A.D. had large
south facing windows to let in the sun's warmth.
By the
sixth century, sunrooms on houses and public buildings were so
common that the Justinian Code initiated "sun rights"
to ensure individual access to the sun.
Conservatories
were very popular in the 1800's creating spaces for guests to
stroll through warm greenhouses with lush foliage.
Passive
solar buildings in the United States were in such demand by 1947,
as a result of scarce energy during the prolonged W.W.II, that
Libbey-Owens-Ford Glass Company published a book entitled Your
Solar House, which profiled forty-nine of the nations greatest
solar architects.
In the
mid-1950's, architect Frank Bridgers designed the world's first
commercial office building using solar water heating and passive
design. This solar system has been continuously operating since
that time and the Bridgers-Paxton Building is now in the National
Historic Register as the world's first solar heated office building.
Low oil
prices following W.W.II helped keep attention away from solar
designs and efficiency.
Beginning
in the mid-1990's, market pressures are driving a movement to
redesign our building systems to more in line with nature. Building
elements that support life are in demand regionally at least and
the American Institute of Architects is supporting a number of
programs to encourage design in this direction.
Pioneers
like Buckminster Fuller have led a design revolution that brings
our values for the built environment back in line with the cycles
of nature.
The American
Institute of Architects (AIA) has become active in promoting energy
saving design through many initiatives including the 1996 Building
Integrated Photovoltaics Design Competition. Literally thousands
of buildings worldwide have successfully demonstrated the design
principles and smart use of materials presented in the overview
of this section. Please go to the Buildings section of BUSINESS
BRIEFS AND PROJECTS for a look at a few of them. (1)
Resources:
(1) AIA Research, 1996
(2) Sklar,
Scott, and Sheinkopf, Consumer Guide to Solar Energy, Bonus Books,
Inc., 1995. p. 7-18.
All the above was resoursed from American Solar Energy Societies
web site, www.ases.org, 2003
