The question of energy savings has been a matter of concern since a long time in the mobile distributed systems and battery-constrained systems. However, for large-scale non-mobile distributed systems, which nowadays reach impressive sizes, the energy dimension (electrical consumption) just starts to be taken into account. In this paper, we analyze the usage of an experimental grid over a one-year period. Based on this analysis, we propose a resource reservation infrastructure which takes into account the energy issue. We validate our infrastructure on the large scale experimental Grid5000 platform and present the obtained gains in terms of energy.