There is increasing research on the exogenous impact of descriptive social norms on economic behavior. The research to date has a number of limitations: 1) it has not de-coupled the impact of the norm and the knowledge required to understand how to change behavior based upon it; 2) it has exclusively used offline but not online (i.e. emails) methods; and 3) it has not understood the impact of financial incentives in conjunction with norms. We address these three limitations using two natural field experiments. We find, firstly, that norms change energy behavior over a 15 month treatment period irrespective of whether information is provided or not. We find that social norms reduce consumption by around 6% (0.2 standard deviations). Norms have has their largest impact on the day that information on the social norm is received, and then decreases over time. Secondly, we do not find that social norms work online (even with experienced consumers who are used to online billing) - social norms de- livered online may have very little beneficial effects on reducing energy use. Thirdly, we find that large financial rewards work very well online in reducing consumption, with a 0.35 change in energy consumption over a four month period. Perhaps most interestingly, we find that the large effect of financial incentives is completely removed when information on social norms is added online.