Climate change is a hot topic which would influence the design and operation of building systems. Many simulation studies focus mainly on the impact of climate change on the overall energy consumption of buildings. This study investigates climatic influences on chiller systems commonly used to provide cooling energy in commercial buildings but with considerable electricity consumption. Climate change scenarios in 2020, 2050 and 2080 were considered to generate forecast weather data based on a typical meteorological year weather file for subtropical Hong Kong. The building simulation program EnergyPlus was used to model an office building with air-cooled and water-cooled chiller systems. Hourly simulations were carried out to examine how different climate change scenarios influence the capacity of the systems and their electricity consumption. The findings indicate that a 3.9-4.2% extension in capacity should be considered for a system to meet the increasing cooling demand over its 15-year functional life. The electricity consumption of the system could increase by 6.8-8.0% over its functional life when operating for the warmer future climate. The ways to enhance the sustainability of chiller systems are addressed. (C) 2012 Elsevier B.V. All rights reserved.