In this study, the decentralized ventilation (DV) performance of a small air ventilator to replace natural ventilation for use in urban areas is analyzed and compared to conventional centralized ventilation (CV) systems in European climates. Selected European weather conditions were used to determine acceptable conditions for the operation of fan-assisted ventilation systems and to analyze the decentralized ventilation system's cooling and heating loads. Entire fan and pump loads of DV system are numerically calculated based on published data. Compared with a conventional centralized ventilation system, this system has shorter air transport distances and therefore entails lower pressure losses. In a decentralized system, fan speed and airflow rate are adjusted simply and effectively depending on indoor thermal conditions. A radiant panel with decentralized ventilation system (RPDV) is shown to have the lowest heating, ventilation, and air conditioning (HVAC) energy consumption because it not only minimizes supply and exhaust air pressure losses, but can also be operated as a fan-assisted natural ventilation system during periods when outdoor air can be used without additional thermal loads. Based on numerically calculated and measured data, this study newly adds fan and pump energy analysis of decentralized ventilation system compared to centralized ventilation systems. This study shows the fan and pump energy consumption with analysis of fan-assisted DV system considering outdoor weather condition in European climate. (C) 2015 Elsevier B.V. All rights reserved.