Decreasing the energy intensity of processes and activities is an important means by which to reduce energy-related carbon dioxide emissions in the near future. Monitoring of the developments in energy intensity is necessary in order to check whether policies to decrease energy intensity have the desired effect. Value-based indicators have been used in many such monitoring studies. It has been suggested only recently that physical indicators might lead to a better understanding of energy intensity developments. In this paper we aim at developing meaningful physical energy intensity indicators for all sectors of the Dutch economy and to study the sectoral energy intensity developments for the period 1980-1995 by means of these indicators. It turned out to be possible to develop aggregate activity indicators on a physical basis for most of the subsectors. Physical and value-based energy intensity indicators yielded substantial differences in the energy intensity developments calculated. On average, the annual decrease in energy intensity for the period 1980-1995 was 1.4%, calculated on the basis of physical energy intensity indicators, and 1.6% on the basis of economic indicators. The methodology based on physical indicators turned out to be suitable for monitoring energy intensity developments. However, more data are required and thorough analysis of the energy consumption per subsector is necessary to improve this type of analysis based on physical activity indicators. (C) 2000 Elsevier Science Ltd. All rights reserved.