Citizens Advice: Energy usage calculator
The energy usage calculator is a simple Javascript application that allows users to understand which of their appliances are costing the most to run, based on individual usage patterns and appliance mix. A ballpark cost for each appliance is displayed, and the user's most hungry appliance is identified.
This is a project that I suggested, prototyped, got "buy in" from the wider team and stakeholders for, developed solely, adjusted in collaboration with the team and stakeholders, had tested by many people, documented and shipped over a period of 8 months.