Research on energy in cities shall pave the way to nearly zero or low-energy districts. Measures include the integration and management of the supply of energy with predominant exploitation of local resources (e.g. waste heat, renewables) and the active participation of consumers (e.g. demand side measures). The cost-effective refurbishment of existing buildings (with a special focus on residential buildings) is targeted by efforts in materials research developing new, sustainable materials. ICT solutions for buildings and districts shall allow for the overall management of local energy and transport systems. This Policy Brochure summarises energy research policies and initiatives in a city context.