The world's primary energy consumption in the last 40 years has been increasing at 2.2%/year while GDP growth has been 3.4%/years over the same period. The decline of the energy intensity (I=E/GDP) has been, therefore, of 1.2%/year. In order to reduce the world's consumption growth proposal have been made to reduce the world's energy intensity by 40% by 2030 which corresponds to a reduction of 2.5%/year, roughly the double of the historical decline. Our analysis shoes that such goal could only be achieved by an unprecedented reduction of the energy intensity of "services" (which represent less than half the world energy consumption) since energy intensity of industry has remained practically constant in the last 40 years. (C) 2012 Elsevier Ltd. All rights reserved.