“…ExternE research group under European Commission developed methods on the monetary valuation of external cost due to the electricity production (European Commission;European Commission, 2005), and these results can be used for other energy carriers. The ExternE methodology is used to weight the impacts according to the preferences of the society, and this methodology has widely accepted and used by the scientific community and considered as the world reference in the fields (Carlsson, 2002a,b;Gebremedhin and Carlson, 2002;Streimikiene et al, 2009;Genon et al, 2009;Difs and Trygg, 2009;Rafaj and Kypreosa, 2007). The monetary values of externalities often included in the heating system are those due to atmospheric emissions of CO 2 , NO x , SO x and particulates generated during fuel combustion.…”