Most countries aim to transform towards becoming greener societies. In parallel, many companies struggle with the question of how to build more sustainable operations while at the same time sustaining or developing their competitive advantage.  Research has, up until today, however, largely failed to provide solid explanations for how to achieve these aims, from which policy and managerial decision-making can deduced. One reason for this failure is that quantitative analysis of “green” innovation at national systems level is not always possible due to the lack of reliable, comprehensive and adequate data sets. In the Swedish case, there are promising data sets, even if one always can debate the adequacy of existing variable definitions. Official data collected by Statistics Sweden (SCB) includes several interesting variables on all private and public organizations in Sweden and all employees, compiled into time series for a number of years. These can be merged with other data sets on the environmental goods and services sector and energy consumption data and therefore allow for a detailed “demographic” or “population ecology” analysis of environmentally oriented or friendly innovation since at least 2003. In this paper, these databases are described in some detail. Problems of definitions and measurement are particularly discussed. Initial explorations describe the shift from fossil to non-fossil energy sources in the Swedish innovation system. Further, we also suggest some models inspired by demography and population ecology and also multi-level models. In particular it is suggested that diffusion models could be applied, including models in which diffusion processes interact in micro-level systems. It is suggested to apply multi-level regression analysis in order to estimate the power of factors affecting the “greening” of Swedish innovation system.