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It is common that the first cost is the main criterion when making choices between different systems. However, it is possible to demonstrate that a lower initial investment can turn out to be more costly from the whole life-cycle viewpoint. With life-cycle cost (LCC) calculations, it is 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 compared in a case-study office building. The LC cost of the system combination where air–water based ventilated beams is utilized in office rooms, variable air volume system in conference rooms and canteen and respectively constant airflow rate in other public areas, was the lowest. The analysis depicts that it is possible to enhance energy efficiency and reduce environmental impact using demand-based air-conditioning without deteriorating the indoor environment