USA, you’re not No. 1. You’re not even No. 2. No, when it comes to energy efficiency, the United States of America is a woeful ninth in a new ranking of 12 of the world’s largest economies, who together make up 78 percent of global GDP, 63 percent of energy consumption and 62 percent of greenhouse gas emissions.The United Kingdom leads the way in the estimation of the American Council for an Energy-Efficient Economy, which based its rankings on a combination of performance and policy metrics. Germany, Italy, Japan and France round out the top five, in that order.