The Worms demonstration project. Comparative investigation of air infiltration and ventilation systems in existing buildings. Demonstrationsvorhaben Worms. Vergleichende untersuchung verschiedener luftungssysteme in ausgefuhrten wohnbauten.

Three blocks of flats on the outskirts of Worms were equipped with a mechanical ventilation system with heat recovery, a mechanical ventilation system, and stack assisted natural ventilation, respectively. Building description, air quality, air change rate, draught protection, noise level, energy balance, individual heating costs, efficiency calculations, planning and installation experience and user behaviour were studied. Systems with heat recovery were found to permit a 15-20 per cent reduction of heat consumption. User behaviour in opening windows is dependent on habit.