Ecological footprint, proposes a kind of “ecological balance” that assesses and compares biologically productive area supply and demand. If the success of this index at a national level is proven, we assume that, to help each organisation or person to apprehend its own contribution to ecological footprint, it can be helpful to develop methods of estimation of ecological footprint at organisational level. For a given sub national system two methods can be used to have an idea of its ecological footprint: (1) The national account based approach is based on the corrections of factors from the national averages of consumptions., (2) The component-based approach is based on an inventory of the consumptions and wastes generated by the observed system, the calculation of standards or specific transfer coefficients. This method seemed to the authors more appropriate. However, it requires several methodological adaptations to the classical ecological footprint methods and it presents some limitations. In order to precise these adaptations requirements and limitations, we developed and experimented such a component-based approach on a real case. Our application field is a road work.