Within the European research project HOPE, 97 apartment buildings and 67 office buildings - of which approximately 75% have been designed to be energy-efficient, and half of them are indeed - were investigated using checklists addressing the building characteristics and ques-tionnaires to the occupants asking their perceived comfort (thermal visual, acoustical and in-door air quality) and health (sick building syndrome and allergies). The analysis of the col-lected data, together with experience gained from former projects and literature lead us to pre-sent guidelines for creating healthy and energy-efficient buildings. These guidelines are pre-sented together with the rationale and facts on which they are based.