Most of the hotels provided two years of energy consumption data, except those that came into operation less than two years ago or have experienced ownership transfer lately. There are three energy sources, namely electricity, gas and diesel used in the hotels. Different energy sources are converted into a common unit (i.e. kWh) based on standard conversion factors to facilitate further analysis. Electricity is the main energy source, with a proportion of 91% in hotels that only use electricity and gas. For other hotels that also consume diesel for hot water or steam generation, the percentage of electricity drops to 77%. Details of these proportions are shown in Fig. 1. EUI was first constructed by dividing the total delivered energy with the hotel’s gross floor area (GFA). This is not only because GFA was found to be the most highly correlated primary factor that explains the variations in energy consumption across different hotels, but also because the Urban Redevelopment Authority of Singapore has detailed guidelines on GFA calculation (URA, 2006), which supposedly most building engineers are well informed of, and hence less confusion will be incurred both in data collection and the application of this benchmark. The mean and standard deviation of the hotels’ EUI constructed in this way are 427 and 96 kWh/m2, respectively.