In this study the multifamily demonstration buildings with demand controlled ventilation systems are discussed. Furthermore,the heating systems together with demand controlledventilation are looked at.There are given examples of the centralized supply and exhaustventilation system, the centralized exhaust ventilation systemand the apartment based ventilation system. All the Systemsare mechanical, natural ventilation is not discussed here. Incold climates natural ventilation, i.e.

A field study of temperature efficiency, air change efficiency and ventilation efficiency in an office room with a displacement ventilation system has been made. The air change efficiency and the ventilation efficiency have been determined by using a tracer gas (N₂0) technique.  Concentrations have been measured at four heights in the room and in the supply and exhaust air.

Using passive sampling techniques, including a passive sampling, multiple tracer gas technique (the PFT-technique), the Danish Building Research Institute has performed field measurements in about 130 dwellings. The dwellings comprised detached, naturally ventilated single family houses and single family houses and flats ventilated with exhaust ventilation systems.