At the request of policy makers a new tool, called MONIT, has been developed for the presentation and analysis of historical energy use and emission trends. The tool is based on the concept of constructed energy balances. The system covers Dutch national and sectoral energy use and the accompanying CO2 emissions, from 1982 onwards. In the presentation part the energy balance with statistical figures is corrected for disruptions in statistics and yearly climate variations. Next to time series for all energy variables and sectors, information is also available about the final demand for electricity or heat and about co-generation, primary energy use as well as direct and indirect CO2 emissions. In the analysis part the energy use developments are mapped with a step-by-step constructed set of energy balances, starting from the base year balance. In each step a supplementary explanatory factor is introduced and the effects are made into an updated balance. In this way the actual changes in energy use are unravelled into 14 explanatory factors, including four different energy-related structural changes, five saving factors, fuel mix changes and changes in export and import of energy. It is possible to reconstruct the actual energy balances within a small margin and most of the 14 contributing factors can be calculated with only a small uncertainty. The MONIT system offers policy makers an integrated set of monitoring results with different levels of information content: statistical data, time series, final and primary energy use, direct and indirect CO2 emissions, intensities and policy relevant contributions to the actual changes in energy and emission variables. (C) 2003 Elsevier Science Ltd. All rights reserved.