Buildings consume approximately 40% of the energy used in America. Half of that energy is used in homes. While the barriers to wide use of renewable energy sources seem great, production of nonrenewable energy sources is dropping while the demand is going up. According to the Tech Energy Network, renewable energy sources that can generate electrical power for homes include wind, solar, geothermal, wave, tidal, hydrogen, and biomass. Most of these can be used in small scale operations for individual homes, or generate mass quantities of power as part of a public utility systems. This subsection addresses several of the renewables that can generate electricity or heat, and are environmentally safe. Its purpose is to give students and teachers information on the state of renewable energies research and application.

Renewable energy is a broad topic and the renewable sources listed above are by no means exhaustive. However, links in this subsection serve to introduce teachers and students to applied and experimental renewable energy technologies for buildings, as well as some of the key organizations involved in their research and development. Other links suggest ways to design homes to more efficiently use energy from renewable sources.

Industry, government, private foundations, nonprofit organizations and higher education are working together to bring renewable technology to market. Developing new technologies is often easier than getting them accepted by or incorporated into the marketplace. Funding the research is often shared by all participants. Teachers and students in building sciences should be aware of this research to best incorporate their study and application into the curriculum, student competitions, model home building and job searches. Below are brief descriptions of some of the prominent organizations involved in renewable technologies for buildings.

National Renewable Energy Laboratory - NREL

The National Renewable Energy Laboratory researches many types of renewable energy sources and applications for homes. In addition to advanced renewable energy technologies, NREL's Center for Buildings and Thermal Systems researches heat transfer through buildings, thermal dynamics and system engineering. Geothermal and solar research are part of the Center's work, as is its association with the Building America program. The next three programs described below are housed under the NREL.

National Center for Photovoltaics

The nation's premier research facility for PV is the National Center for Photovoltaics (NCPV), headquartered at NREL. The Center performs fundamental research in PV-related materials; develops PV cells in several material systems; characterizes and improves performance and reliability of PV cells, modules and systems; assists industry with standardized tests and performance models for PV devices; and helps the PV industry accelerate manufacturing capacity and commercialization of various PV technologies.

National Wind Technology Center

The National Wind Technology Center, located at the foot of the Rocky Mountains near Boulder, Colorado, is a research facility managed by the National Renewable Energy Laboratory for the US Department of Energy. NWTC researchers work with members of the wind energy industry to advance wind power technologies that lower the cost of wind energy through research and development of state-of-the-art wind turbine designs. Wind energy, usually harnessed by windmills, is the fastest growing power source in the world. Modern windmills convert the natural movement of the air into electricity, the largest of which can range from 150 to 2,000 kW in electric capacity, and are used by electric generators to supply electricity to the power grid.

Hydrogen Production and Fuel Cells

Hydrogen is the simplest and most abundant element in the universe. Hydrogen can be produced from a wide variety of domestic resources using a number of different technologies. Almost all of the hydrogen produced in the US today is by steam reforming of natural gas and for the near term, this method of production will continue to dominate. Researchers at NREL are developing a wide range of advanced processes for producing hydrogen economically from sustainable resources. The cleanest way to produce hydrogen is by using sunlight to directly split water into hydrogen and oxygen.

Fuel cells harness the chemical energy of hydrogen to generate electricity without combustion or pollution. Fuel cells are an important enabling technology for the hydrogen economy and have the potential to revolutionize the way we power our nation, offering cleaner, more-efficient alternatives to the combustion of gasoline and other fossil fuels. NREL's work supports DOE's focus on core technologies to improve fuel cell systems and the various subsystems and components that comprise them. Specific research areas at NREL include fuel cell system analysis and fuel cell component materials.

Rocky Mountain Institute

The Rocky Mountain Institute is an entrepreneurial nonprofit organization that fosters the efficient and restorative use of resources and their fair and sustainable distribution. Staff works with businesses, communities, individuals, and governments to create more wealth and employment, protect and enhance natural and human capital, increase profit and competitive advantage, and enjoy many other benefits - largely by doing what they do more efficiently. RMI's Green Development Services, for example, pursues environmental excellence through buildings and communities that are more comfortable, efficient, appealing, and ultimately more profitable.

National Center for Appropriate Technology - NCAT

National Center for Appropriate Technology (NCAT) projects range from low-tech to high-tech, addressing complex issues of housing, economics, and environmental quality. Weatherizing houses, monitoring energy use, demonstrating renewable energy technology, testing new products and providing information on building construction are just a few of the many ways that NCAT has contributed to fostering healthy communities and a better quality of life for everyone. NCAT's Sustainable Energy program is a cornerstone of its efforts. It operates projects in the areas of renewable energy, affordable energy, and affordable housing.

Department of Energy - Million Solar Roofs Initiative

The Million Solar Roofs Initiative is a unique public-private partnership aimed at overcoming barriers to market entry for selected solar technologies. The goal of the Initiative is practical and market-driven: to facilitate the sale and installation of one million "solar roofs" by 2010. Eligible technologies include photovoltaics (PV), solar water heating, transpired solar collectors, solar space heating and cooling and pool heating. This site provides links to many major solar power information resources

Department of Energy - GeoPowering the West Program

The Department of Energy's GeoPowering the West (GPW) program works with the US geothermal industry, power companies, industrial and residential consumers, and federal, state, and local officials to provide technical and institutional support and limited funding to state-level activities.

Geothermal energy represents a major economic opportunity for the American West, an area characterized by a steadily increasing population that requires reliable sources of heat and power. Of prime importance in the development of this resource is the Great Basin Center for Geothermal Energy at the University of Nevada-Reno. The center is largely funding through the GPW program. Its mission is to work in partnership with US industry to establish geothermal energy as a sustainable, environmentally sound, economically competitive contributor to energy supply in the western United States. Links at both of these sites connect with important geothermal work throughout the country.

Putting it all Together - HOMER

The above sources do not cover all the possibilities currently available for renewable production of energy for buildings. With the vast array of renewable energy configurations for power generation possible, making the best decision is important, as well as potentially complex. The answer could lie in NREL's Hybrid Optimization Model for ElectricRenewables, otherwise known as HOMER. HOMER is a computer model that simplifies the task of evaluating design options for both off-grid and grid-connected power systems for remote, stand-alone, and distributed generation applications. HOMER's optimization and sensitivity analysis algorithms allow you to evaluate the economic and technical feasibility of a large number of technology options and to account for variation in technology costs and energy resource availability. HOMER models both conventional and renewable energy technologies.