The American electricity company Opower use social normative messages comparing a person’s electricity usage to that of their neighbours to reduce electricity consumption. This is an area with interesting diversity of findings. Schultz et al (2007) found the use of normative messages with injunctive emoticons effective at reducing consumption. Allcott (2011) estimates this program reduces consumption by around 2% for Opower’s customers.Interestingly, Costa & Kahn [2010] found this kind of normative nudge may backfire with political conservatives, who may actually increase their electricity consumption in reactance to it.