The Joint Research Centre provides scientific and technical support to the European Commission and supports the Covenant of Mayors initiative. The Covenant of Mayors requires cities to develop Sustainable Energy Action Plans (SEAPs) to reduce CO2 emissions 20% by 2020. Developing accurate SEAPs and monitoring progress requires reliable energy consumption data collected through baseline and monitoring emission inventories. However, data collection presents challenges as data is organized differently between countries and sectors. Energy audits and energy management systems can help cities develop better SEAPs and improve data quality for monitoring.