Double facades are built to allow natural ventilation in high-rise buildings and buildings with high outside noise levels. To evaluate the energetic performance, three buildings with double facades were monitored for at least I year (Siemens building in Dortmund, Victoria Insurance Company in Dusseldorf and RWE Tower in Essen). In one building all the air conditioning facilities had been removed and the facade replaced by a double facade, one building had cooling equipment without mechanical ventilation (concrete core tempered ceiling) and one building had cooling equipment combined with mechanical ventilation. The results document the indoor climate, the boundary conditions for further planning and the possibilities for high-rise buildings with no or only limited cooling facilities. The research was carried out at the University of Dortmund and founded by the state of Nordrhein-Westfahlen (AG-Solar). (C) 2004 Elsevier B.V. All rights reserved.