Green Electricity Opt-Out Default
German utility companies · Germany · 2016
Summary
Simply making green energy the starting position—requiring households to actively switch away rather than actively choose it—increased adoption by nearly tenfold. The effect holds across income levels, regions, and household types. This is one of the strongest demonstrations of default power in a domain with meaningful individual financial cost, since green tariffs typically carry a small premium.
Research question
"Does setting green energy as the default tariff increase adoption compared to opt-in?"
Methodology
Intervention
Green electricity set as default (opt-out required) vs. standard opt-in for green tariff
Assignment
Randomized controlled trial (household)
Sample size
~7,000 households across multiple trials
Primary outcome
Green electricity contract enrollment
Effect estimate
Opt-out adoption: 68–94% vs. opt-in: 7–41% (roughly 10× difference)
Decision
Multiple utilities adopted opt-out green defaults; replicated in UK and elsewhere
Result
Positive
Opt-out adoption: 68–94% vs. opt-in: 7–41% (roughly 10× difference)
Evidence strength
Strong
Randomized trial, replicated across multiple sites or studies.
Replication status
Replicated
Institution
German utility companies
Location
Germany
Year
2016
Policy area
Energy & Environment
Mechanism
Default