Chillers are major energy consumers in industrial facilities. They are indispensable in such industries as semiconductor fabrication, food processing, and plastics manufacturing, among others. Previous studies aimed at improving the energy efficiency of chilled water systems have focused on optimizing the performance of individual chillers. However, an alternative method to recover energy is to perform system-wide water source/sink integration using a superstructural approach. In our previous study, several schemes for chilled and cooling water systems (CCWS) with hub topology were proposed for energy savings. The main contribution of this study is in the development of a methodology to achieve energy savings by introducing free cooling in an integrated superstructure for CCWS. Two examples are used to demonstrate three different scenarios of CCWS with free cooling. It is shown that the integration of free cooling into chilled water system improve the cost and energy saving significantly, and can avoid the need to invest in a new chiller and/or cooling tower to enhance the energy efficiency of CCWS. (C) 2015 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.