A 21st century community building should be multi-functional, flexible and open for the local community, but first of all it should be sustainable and green. This is how we imagined and delivered the design from the competition concept till the detailed construction documents for the Municipality of Rákosmente, a low density garden city at the outskirts of Budapest. The functional program was mainly focusing on the everyday sport and leisure activities, and a restaurant, a café and other services were also included. The main hall was capable to host larger sport and cultural events up to 2000 persons. Renewable primary energy sources such as heat pumps with underground heat exchange pipes and solar panels secured more than 75% of the total energy consumption of the building.