The article explores how people respond to policies that promote energy efficiency. It shows that different people react differently to incentives like taxes and subsidies. Subsidies may not always be cost-effective because of this. When people don't understand their energy use well, subsidies may not work as intended. In the UK, early adopters of energy-efficient technology tend to use more energy before switching and then use less after. This suggests that people's preferences, not just their beliefs, influence their decisions. Overall, the study finds that people's differences in preferences, not beliefs, drive their choices about energy efficiency.