The renewed Energy Performance of Building Directive and European regulations for buildings energy efficiency are becoming increasingly restrictive and moving towards near zero energy buildings. To achieve this goal, amongst others measures, a building utility system has to be carefully designed and optimized to perform efficiently and to utilize renewable energy source to greater extent. This paper is focused on the multi-objective performance optimization of buildings free cooling systems. The optimization was twofold: firstly, the energy consumption and available free cooling potential were estimated using weather forecasts, and secondly, the free cooling system operation regime was optimized to meet the required energy consumption using variable air distribution and flow control. The results of the optimization show the significant influence of such system operation control on system performance indicators. (C) 2012 Elsevier B.V. All rights reserved.