The Institute of Building Services and Energy Design - IGS of Braunschweig Technical University is one of Germanys leading research establishments concerning energy optimised construction. Focuses are demonstration buildings and evaluations of existing buildings. Innovative concepts of refurbishment of schools and museums are being developed as well as solar-assisted energy concepts of district heating. The IGS is covering the whole spectrum of technical building equipment and building physics as well as passive and active use of solar energy for residentials and office buildings. Main emphasis is put on integrated planning and sustainable refurbishment of buildings under consideration of all aspects relevant for a buildings energy performance and its indoor comfort.