Saving energy – through efficient and wise energy use – helps protect the environment. When we save on energy use, we help prevent carbon dioxide (CO2) emissions and other forms of air pollution. Energy efficiency is a smart practice that helps the economy, too, by saving consumers and businesses million of dollars in energy costs each year. Research and innovation continue to bring high-performing, energy efficient products and technologies to the marketplace.
CO2 is the key greenhouse gas responsible for global warming concerns. The overwhelming share of U.S. and world carbon dioxide emissions comes from burning fossil fuels, such as oil, coal and gas – our main sources of energy. Burning fossil fuel causes emissions of other greenhouse gases as well, such as methane (CH4) and nitrous oxide (N2O).
EPA has several initiatives – often in collaboration with the Department of Energy – underway with industries, consumers, and state and local governments to improve energy efficiency across all sectors of the economy. Energy efficient products and technologies are saving money and improving overall energy performance in commercial buildings, school systems, local governments, homes, transportation networks, electricity plants, and many other areas.
Each of us can help prevent global warming and save ourselves money through our own purchasing decisions and lifestyle choices. There are plenty of opportunities. When purchasing a new automobile, for example, consider how many miles per gallon it gets (visit DOE's Fuel Economy Site). 
Consider car pooling, taking public transit if available, or possibly riding your bike to work, among other options.
There are simple ways to save energy at home, as well. The electricity we use in our homes is usually generated by combusting coal, oil, or natural gas at a nearby power plant. So the less energy we use at home the more pollution we can prevent. When buying or replacing products or appliances in the home, look for the ENERGY STAR® label – the national symbol for energy efficiency. Products with the label save energy, save money on utility bills, and help protect the environment.