Reseachers in Ludwigsburg (Germany) have developed a district energy concept by combining the advantages of ambitious building concepts and refurbishment measures with energy efficient heat supply; a local heating network for two city districts- the existing district of Grünbühl and the Sonnenberg development area. The heat generation is realised by a combination of a brine-water heat pump and a combined heat and power plant. BINE project info 04/2015 explains the concept, presents the advantages and analyses general success factors for district energy concepts.