It is common that the first cost is the main criterion when making choices between differentsystems. However, it is possible to demonstrate that a lower initial investment can turn out tobe more costly from the whole life-cycle viewpoint. With life-cycle cost (LCC) calculations, itis possible to get a better overview of the total cost. LC costs of typical systems (fan-coil,constant airflow rate, variable air volume and ventilated beams) were analysed and comparedin a case-study office building. The LC cost of the system combination where air-water basedventilated beams is utilized in office rooms, variable air volume system in conference roomsand canteen and respectively constant airflow rate in other public areas, was the lowest. Theanalysis depicts that it is possible to enhance energy efficiency and reduce environmentalimpact using demand-based air-conditioning without deteriorating the indoor environment.