Cities are responsible for about 30% of the energy consumed worldwide. Since 2007 more than 50% of the world population lives in cities, and urbanization is still growing. The energy-efficiency of cities is gaining greater importance today. The paper examines the possibilities of energy consumption reduction and optimization in cities. Various urban and architectural tools are described below that affect indirectly and directly the energy balance of cities. The possible ways of using renewable energy sources in cities have been analyzed. Ways and means of their use is analyzed in on-site, nearby and off-site systems.