An Overview of U S Department of Energy's
"Solar Buildings Program"
Buildings account for more than one
third of the energy used in the United states each year, consuming vast amounts of
electricity, natural gas, and fuel oil, Given this level of consumption, The building
sector is rife with opportunity for alternative energy technologies, The U.S Department of
Energy’s (DOE’S) Solar Buildings program was established to take advantage of
this opportunity
The
Solar Buildings Program is engaged in research, development and deployment
(RD&D)
on solar thermal technologies which use solar energy to produce heat. The program focuses
on technologies that have the potential to produce economically competitive energy for the
buildings sector .by working closely with manufacturers in the buildings and solar energy
industries and by supporting research t universities and national laboratories, the solar
buildings Program brings together the diverse players developing reliable, economically
viable solar thermal technologies for building applications The program also works
collaboratively with builders, utilities and energy service companies
The
Solar Buildings Program’s solar thermal focus is driven by the need for thermal
Why
Solar Buildings?
We
are familiar with the environmental and economical benefits of reducing our dependency on
energy generated by the combustion of fossil fuels. The steps we take today developing
alternative, cost effective energy technologies will pay of tomorrow in increased energy
stability and improved environmental quality
A
Look at energy consumption within the building sector demonstrates the importance of
continued
Alternative
energy technology development Of the 94 quadrillion Btus (Quads) of energy consumed
annually in the United States buildings account for 34 Quads, or about 36% Residential
water heating alone accounts for 2 Quads. Studies estimate 70% of new homes (approximately
1 million per year) could be designed to accommodate energy-producing solar technologies.
By the year 2020 therefore, solar hot water systems could potentially supply 15%-25%(0.5
Quads) of the energy used for home water heating. *Although these figures pertain only to
residential water heating, they are representative of the impact that solar technology
could have on the buildings sector in the coming decades. In addition to these benefits,
solar buildings technologies offer a number of other advantages when compared to competing
source of power]
Energy
diversity. By developing solar technology,
we diversify our energy supply and reduce our susceptibility to fluctuations in the availability and price of imported
fossil fuels.
Economic
development. A mature solar manufacturing and service industry promotes job
creation and local economic development.
Consumer
satisfaction. Recent surveys and consumer choice utility programs demonstrate
customer preference for clean source of energy.
Environment
efficiency. Each solar water heating system reduces carbora emission by an amount
equivalent to the emissions from an automobile
Solar Thermal Systems and Collector Technologies
Solar
building technologies convert sunlight into usable forms of thermal energy such as hot
water and heated air .The key component in all solar building technologies is the
collector – the device that converts the sun’s radiant energy to heat . In
general ,most of the collector designs used in buildings applications fall into one of
five categories.
Flat-Plate
Collectors-Commonly used in residential and commercial buildings, these
collectors convert ambient levels of solar radiation for low-temperature (less than 180 F)
water –and air-heating applications.
Evacuated-Tube
Collectors—Similar to flat-plate designs, evacuated –tube collectors
employ a vacuum within a glass cylinder to reduce heat loss to the surrounding environment
and generate high operating temperature (170-350 F).
Concentrating
Collectors—Unlike flat-plate designs, which operate on ambient sun light,
solar trough collector and compound parabolic concentrating collectors use curved mirror
to concentrate sunlight on the receiver at up to 60 times its normal intensity. These high
–temperature system are used primarily in commercial and industrial applications.
Transpired
Solar Collectors –Used to heat large volume of air, these innovative yet
simple collectors are typically installed on a large portion of a building’s
south-facing wall. Sunlight heats the surface of the collector, which in turn heats air
being drawn through the perforations in the collectors. See the photo on this page
Unglazed
Flat-Plate Collectors—commonly used for heating swimming pools, these
collectors provide low-temperature energy to lengthen the swimming season
These solar thermal collector designs can be integrated into a variety of systems to meet
specific thermal energy needs these systems exploit local operating factors such as
geographic location, climate, and annual average level of solar radiation. As opposed to
passive solar thermal systems—which directly heat air or water –active systems
use a heat-transfer medium such as antifreeze or oil to transfer thermal energy from the
collector to the end use load, such as water or space heating.
Active
solar systems incorporate mechanical systems to distribute the energy collected. This
include piping control systems.duct-work,pumps,heat exchangers,fans,and other mechanical
components.these are the same components commonly used in the plumbing and heating
industries,and they integrate the solar system with a building’s conventional heating
ventilating, and air-conditioning system.
Passive
systems common in residential water heating merge the solar collector with a storage
system. Passive system are used primarily in areas where the temperature rarely is below
freezing. These systems do not incorporate pumps, controllers, or other mechanical
components of active systems, they usually are less expensive than active systems, but
they generally are less efficient, as well.
DOE’s SOLAR Buildings Program: RD&D on
a Broad Front
The
solar Buildings Program is sponsoring a broad range of RD&D to bring solar building
technologies into wider use.with its focus on technology development.The Program conduct
application-oriented RD&D on established and next –generation solar thermal
technologies
Two
DOE national laboratories – the National Renewable Energy Laboratory (NREL) in
Golden,Colorado,and sandia National Laboratories(SNL) in Albuquirque, New
Mexico—jointly participate in the Solar Buildings Program. In addition to conducting
RD&D, the two national laboratories work closely with industry and university to
develop technology improvements, reduce manufacturing cost monitor system performance, and
identify potential new markets for solar buildings technologies.
Program
researchers are engaged in fundamental technology development in areas such as improved
heat-exchange research, advanced coating for absorbers, and solar cooling Substantial
system cost reduction are being pursued through the development of alternative concept,
such as a polymer-based collector that could cut life –cycle costs in half
Researchers
are also investigating the use of low-cost solar thermal systems in agricultural
applications, such as crop drying. The initial work in this area is focusing on
crop-drying process in Latin America and Africa, where drying is accomplished by burning
large amounts of timber .The crop-drying research is part of larger effort to adapt solar
building technology to additional markets enabling U.S.solar thermal manufacturing to
expand exports.
In
other development efforts, the Program works closely with the solar and buildings
industries to improve manufacturing process and overcome the barriers to wide spread use
of solar technologies, Program engineers and SNL and NREL staff are assisting a number of
solar manufacturers to streamline their process and reduce overall system costs by
10%-20%.
Program
researchers at NREL are conducting a series of workshops and surveys to determine the
areas of solar thermal technology development deemed critical by utilities builders, and
consumers .The Program is soliciting this stake holder feedback to help the solar industry
meet developing market trends. NREL and SNL are using the information gathered through
these efforts to focus their RD&D.
In
related work, the program is supporting the Doe’s Million Solar Roofs Intiative,
which aims to place 1 million solar energy systems on the roofs of homes and buildings
across the Unites States by the year 2010.The solar Building Program Contributes
Homebuilders Research Center .It also seeks partnerships with homebuilders and utilities
to help them determine the potential of solar energy to meet the needs of their customers.
Summary:
Through
its RD&D in solar thermal technology .DOE’s Solar Buildings Program is working
towards expanding the use of dependable cost-effective renewable energy In the buildings
sector.The Program welcomes the participation of the solar and building industries as well
as qualified researchers from the academic community .For additional information about the
Solar Buildings Program;
Visit the Solar Buildings Program web site
www.eren.doe.gov/solarbuilding
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