The methodology for baseline building energy consumption is well established for energy saving calculation in the temperate zone both for performance-based energy retrofitting contracts and measurement and verification (M&V) projects. In most cases, statistical regression models based on utility bills and outdoor dry-bulb temperature have been applied to baseline monthly and annual whole building energy use. This paper presents a holistic utility bills analysis method for baseline whole building energy consumption in the tropical region. Six commercial buildings in Singapore were selected for case studies. Correlationships between the climate data, which are monthly mean outdoor dry-bulb temperature (T-0), relative humidity (RH) and global solar radiation (GSR), and whole building energy consumption are derived. A deep prediction study based monthly mean outdoor dry-bulb temperature (T-0) and whole building energy consumption is stated. The result shows that variations of the energy consumption in most of these buildings are contributed by T-0 and can be well predicted at 90% confidence level only with it. The analysis of such kind of model is especially useful for building managers, owners and ESCOs to track and baseline energy use during pre-retrofit and post-retrofit periods in the tropical condition. (C) 2004 Elsevier B.V. All rights reserved.