More than a quarter of the non-residential buildings in Europe are public buildings and their energy consumption is forty percent higher than that of residential buildings. Therefore, promoting a public policy to increase energy efficiency of the HVAC systems in public buildings will have a significant impact in reducing global energy consumption. In order to have a precise estimation of the impact of the substitution of the HVAC systems in a large number of public buildings, it is essential to have accurate data of the performance of these systems in specific buildings, beyond the technical specifications stated by the manufacturers. In this paper the substitution of the wide-spread, conventional air-condensed chiller (ACC) for a water-condensed chiller (WCC) with a dry-adiabatic cooler in a public administration building is analyzed in terms of energy efficiency, economic return of the required investment and environmental implications. The influence of external factors as well as the load effect are quantified. The results show that the seasonal Energy Efficiency Ratio of the WCC is near twice that of the ACC, making the replacement of the ACC for the WCC an interesting option. The results obtained in this study could be extrapolated to other non-residential public buildings. (C) 2015 Elsevier B.V. All rights reserved.