Passivhaus buildings provide a high level of occupant comfort while using very little energy for heating and cooling. They are built with meticulous attention to detail and rigorous design and construction according to principles developed by the Passivhaus Institute in Germany. Passivhaus Trust This excellent environmental performance is achieved through a combination of near-airtight buildings, very high standards of glazing and insulation, alongside mechanical ventilation systems. This essentially means that the buildings rely on solar energy and the heat of the occupants to keep them warm for the vast majority of the time, filtering the airflow and recovering any excess heat to be reused.