Many scientists have accepted that human activities are the major cause of climate change and global warming. Knowledge on the effect this will have on office buildings and energy consumption in the future is essential. Thus the assessment of future building energy consumption is becoming more important especially in countries such as Malaysia where the majority of the office buildings depend on air-conditioning to maintain the occupants level of comfort. This research explores the effect of future climate change weather on the energy consumption of office buildings in Malaysia, by using simulation software. Simulated weather data sets HadCM3 were supplied by the Hadley Centre in the United Kingdom for the recent past and for the future up to 2099. Test Reference Years (TRYs) were selected from this data using the Finkelstein-Schafer Statistic (FS) method for four time slices, namely TRYs 1990-2007, 2010-2039, 2040-2069 and 2070-2099. The HadCM3 data was validated by comparing the 1990-2007 TRY with a TRY selected by the same method and period from the measured weather. The Hadley data was supplied as daily values, but the building simulation software required hourly values. Algorithms were therefore used to generate hourly values from the daily data for the relevant variables (dry bulb temperature, relative humidity, wind speed and global solar radiation) and to decompose global solar radiation into direct and diffuse radiation.Two different office building were modelled in the simulation software, one imaginary simplified typical building and one real building. The sensible and latent annual cooling loads were found for each building for each different TRY. A sensitivity analysis was also performed to investigate the effect on cooling load of changes in building design as possible ways of mitigating the effects of climate change. It was found that climate change will increases the building energy consumption by 13.6 percent in future and better understanding on building design will reduce this effect.