. . . . . . . . . . "Energy efficient buildings, industrial processes and transportation could reduce the world's energy needs in 2050 by one third, and help controlling global emissions of greenhouse gases, according to the International Energy Agency. Energy efficiency and renewable energy are said to be the \u201Ctwin pillars\u201D of sustainable energy policy. However, there are many problems in calculating energy usage, and even bigger problems when discussing environmental impact."@en . "Energy efficient buildings, industrial processes and transportation could reduce the world's energy needs in 2050 by one third, and help controlling global emissions of greenhouse gases, according to the International Energy Agency. Energy efficiency and renewable energy are said to be the \u201Ctwin pillars\u201D of sustainable energy policy. However, there are many problems in calculating energy usage, and even bigger problems when discussing environmental impact."@en . "Efficient energy use"@en .