Best way to survey people about their home energy usage habits?

Social desirability bias is huge with energy topics — people always claim to care more about sustainability than they actually do. Try using behavioral questions instead of attitudinal ones, like 'what did you actually do last month' rather than 'how important is green energy to you.' Indirect techniques like asking about 'people like you' or using a conjoint exercise where cost vs. solar tradeoffs are forced can also surface more honest preferences.