Non-binding Defaults and Voluntary Contributions to a Public Good - Clean Evidence from a Natural Field Experiment

We conducted a large scale field experiment to test whether framing a voluntary contribution decision with different non-binding defaults affect people's behavior. On an electricity provider's website, we manipulated non-binding green energy defaults in electricity contract offers. The default was either green or non-green. Buying green is costly and protects the environment. Hence, it is a voluntary contribution to a public good. Our core results are: First, defaults have a strong effect on contributions. 69% of new customer buy green, when the default was green, but only 7% when the default was nongreen. Second, the fraction of website visitors signing an electricity contract is similar across treatments. Third, regional election results affect green energy choice of customers.