In the US computing centres are built with up to 25 MW electric power. In Switzerland, the CSCS is planning a new centre with a few MW installed. And this trend continues, one already talks about the exaflop (one exaflop per second: 1 EF/s = 1018 operations per second) machine in 2018. Consider that each node in a parallel machine consumes today about 200 Watts, half for the processor, half for the main memory subsystem. Such a node delivers perhaps 200 GF/s thanks to an increasing number of cores. To reach one EF/s, millions of such nodes must be put together. This would lead to a power consumption comparable to a nuclear power plant. Do we really need an exaflop machine? Or should we rather build computers that are adapted to HPC application needs, and, as a consequence, consume much less energy? I believe that Switzerland could be the first country to do so.