Using energy efficiently is a major tool in the State's effort to reduce its near total dependence on petroleum for its energy needs. By using energy efficiently, Hawaii's people can reduce the amount of fossil fuels imported to generate electricity. By switching to energy-efficient appliances, equipment and pratices, people can defer the need for new petroleum-or coal-powered generation facilities. Two of the differences in energy conservation between Hawaii and the Mainland are climate and fuel availability. On Mainland, due to its colder climate, it has to use insulation to hold heat inside houses. However, Hawaii uses single wall construction and is not really concered with heat-loss. Fuel availability is another problem Hawaii faces. The Mainland has great amounts of fossil fuels to use for heating and other energy needs. Hawaii has no fossil fuels because the Hawaiian Islands are still very young and have not had the time to develop underground.