Energy efficiency is defined as using less energy to provide the same level of energy service. Some examples of energy efficiency are better insulation of buildings, using energy saving light bulbs, buying cars with better gas mileage. Energy efficiency is achieved primarily by means of a more efficient technology or processes rather than by radical changes in individual behavior.
Energy Star is an international standard for energy efficient consumer products. It was first created as a United States government program in 1992, but Australia, Canada, Japan, New Zealand, Taiwan and the European Union have also adopted the program. Devices carrying the Energy Star logo generally use 20%–30% less energy than required by federal standards.
Regular or incandescent light bulb uses four to five times more energy than compact fluorescent light to produce same amount of light. Since lighting accounted for approximately 9% of household electricity usage in the United States in 2001, widespread use of compact fluorescent light could save as much as 7% of total US household usage.
If every US home replaced just one light with an Energy Star efficient light, saved energy would be enough to light more than 3 million homes for a year and prevent 9 billion pounds of greenhouse gas emissions per year, equivalent to the emissions of about 800,000 cars.
Energy Star qualified clothes washers use about 30% less energy and use over 50% less water than regular washers. The average American family washes almost 400 loads of laundry each year. If your washer is over 10 years old then replace it with a new energy efficient washer and you could save $135 each year on your utility bills.
Average passenger car fuel consumption in the United States is 22.4 miles per US gallon (about 10.5 liters per 100 km) and the same average in European Union is a bit more than 40 miles per gallon (less than 6 liters per 100 km). That is mainly because the US citizens prefer massive SUV-like vehicles and fuel prices are considerably lower than in EU so the fuel economy is not very important in the US. If citizens in the United States would accept cars with EU fuel economy there would be savings of about 32.9 billion gallons of fuel per year (42.1 billion gallons per year instead of current 74.0 billion gallons). From ecology perspective that would be more than 300 million tons less carbon dioxide released into atmosphere per year.
Although both terms are related to saving energy, the terms energy conservation and energy efficiency have two distinct definitions. Energy conservation is any behavior that results in the use of less energy – behavioral change. Energy efficiency is the use of technology that requires less energy to perform the same function – technological change.
The United States and Germany are countries with almost the same standards of living, but average US citizen uses twice as much energy than average German. Reasons for that difference are quite complex, but we will mention two main reasons. First reason is cheap energy in US that does not motivate people to invest in energy efficiency. Second big reason is inferior spread of high-tech and energy efficient technology in US comparing to Germany.
Since buildings use 40% of the total energy in the US and European Union, energy efficient houses are becoming more and more interesting. In Germany a "Low Energy House" has an energy consumption limit of 50 kWh/m² per year for space heating. In Switzerland the term is used in connection with the MINERGIE standard - no more than 42 kWh/m² per year should be used for space heating.
In the United States, a house built to the Passive House standard uses between 75 and 95% less energy for space heating and cooling than current new buildings that meet today's US energy efficiency codes. The Passivhaus in the German-language camp of Waldsee, Minnesota uses 85% less energy than a house built to Minnesota building codes. The Passivhaus standard for central Europe requires that the building must use less than 15 kWh/m² per year in heating and cooling energy.