We study empirically the effectiveness of a customer information program to decrease energy demand by increasing efficient electricity use. This demand side management (DSM) program aims at reducing the lack of information on the customers' side that is documented in related literature. We study the Irish DSM program which is particularly well suited to investigate this issue as strategic behavior is ruled out in this setting for both customers and suppliers. On the customers' side because information programs allow only for a limited substitution of own effort. On the producers' side because the specificity of the Irish case left no room for strategic behavior. We find that providing customers with information reduced overall electricity demand by roughly 7%, as well as reducing demand fluctuations over the year. Further, we find that the DSM program had a larger impact upon long run demand, with consumers' short run demand behavior not being changed significantly. (C) 2003 Elsevier Science Ltd. All rights reserved.