CarbonCulture is an energy efficiency platform that creates substantial energy savings through measuring and managing energy use across complex estates. It engages stakeholders through online reports and displays to optimize energy use and share best practices. It has saved up to 10% on energy bills for initial clients and received enthusiastic responses, demonstrating its impact through measurable carbon reductions and behavioral changes. The biggest challenges are strengthening the evidence base and managing rapid growth, which can be addressed through partnerships and building a larger membership base.