Total impact multipliers (TIMs) are factors derived from input-output analysis (IOA) that show the total, economy-wide attribution of impacts from production to one unit of final demand. One example is the attribution of greenhouse gas (GHG) emissions of all industries in an economy to the final demand of a particular product. This metric is called the carbon footprint of the product (Gao et al. 2014;Peters 2010;Wiedmann 2009). More precisely, it is the cradle-to-sale, life cycle inventory of total upstream GHG emissions released during the production of the product.TIMs (denoted as m in the following equations) are the typical result of a demand pull, Leontief Type I calculation in the standard Leontief quantity model (Miller and Blair 2009, p. 447where f is a matrix of direct intensity factors (or direct impact multipliers, DIMs), i.e. factors that represent the direct impact intensity of an industry (or sector) in the form of the total impact F of this industry divided by the industry's total output X (i.e. f = F · X −1 ).
AbstractThis note describes a simple technique of decomposing total impact multipliers derived from input-output analysis. The approach uses a generalised supply and use table framework, explicitly distinguishing between industries and products. Contributions to total impact multipliers can be shown by either industry origin (answering the question: Where is the source of impacts and how large is the impact from that particular source?) or product embodiments (answering the question: What are the life cycle impacts of those products that are directly used in the production of a good or service?). Such information is routinely used in life cycle assessments and (hybrid) input-output analyses. A practical example of decomposing carbon footprint intensities of renewable electricity generation technologies is presented, and an Excel worksheet and MATLAB code accompany this note as Additional files 1 and 2.