“Non-monetary incentives that encourage pro-environmental behaviour can contribute to combating climate change. Here, we investigated the effect of green energy defaults in the household and business sectors. In two large-scale field studies in Switzerland of over 200,000 households and 8,000 enterprises, we found that presenting renewable energy to existing customers as the standard option led to around 80% of the household and business sector customers staying with the green default, and the effects were largely stable over a time span of at least four years. Electricity consumption had only a weak effect on default acceptance. Our data do not indicate moral licensing: accepting the green default did not lead to a disproportionate increase in electricity consumption. Compared with men, women in both the household and business sectors were slightly more likely to accept the green default. Overall, non-monetary incentives can be highly effective in both the household and business sectors.” in nature human behvaiour.