In this paper, we present the results of a three-year investigation of the relationship between billing information and household energy consumption in Oslo, Norway. The hypothesis tested in the study is that a more informative energy bill will result in more efficient energy use in the home. The consumption data from the third and final year of the experiment confirm the hypothesis in a resounding way: more informative bills resulted in energy savings of about 10%. Questionnaire and interview data show that those who received experimental bills paid more attention to the bills, were more likely to discuss bills with other members of the household, and were positive to continuing with the experimental billing system. There are greater costs associated with the more frequent and informative bill which was tested, but we have estimated that costs are minimal in relation to savings. Each kWh of saved energy has a cost of only about 0.07 Nkr ($0.01). Since the techniques which were tested do not require extensive training or major technical innovations, they can be easily put into practice. These results on energy savings and consumer response to better billing feedback should be of interest to the many utilities around the world which have billing systems similar to the one in Oslo.