In the present paper, a possible application of information theory for urban system analysis is shown. The ESM method proposed, based on Shannon's entropy analysis, is useful to evaluate different alternative measures of new energy saving technology transfer at different programming stages for consumption reduction and environmental impact control. A case study has been conducted in an urban area of Florence (Italy): the action/factor interaction entropy values can provide a scale of intervention priority and by comparing results obtained evaluating conditional entropy, ambiguity and redundancy, it is possible to identify the highest energy sustainable intervention in terms of higher or lower critical and risky action/ factor combinations for the project being carried out. The ESM method proposed, if applied to different urban areas, can provide a rational criterion to compare complex innovative and sustainable technologies for irreversibility reduction and energy efficiency increase. (c) 2005 Elsevier Ltd. All rights reserved.