Analyzing the products sold on our marketplaces demands certain specific calculations and conversions. In order to develop emission data for material extraction, material production, and waste management, IVL developed material partitions for the various product categories on each site. In each selected product category, random sample tests on 10-50 published ads were made. These ads were analyzed and the products’ average material partition was calculated.
An average product in category ”Sofas & Chairs”, for example, consists of 30 percent wood, 11 percent steel, 18 percent polypropylene, 20 percent polyurethane, 10 percent polyester, 7 percent cotton, 3 percent leather, 1 percent wool. In all, 20 material partitions were produced; each representative to at least one of the selected product categories. That several categories fit into the same material partitions is due to the fact that a car stereo, for instance, has a similar material partitions as a home stereo system, but the products are found in various categories on each site.
Basis for calculation
For the calculation of savings in terms of materials we have only considered the weight of the material composition of a product and included the materials plastic (all types of plastic materials), steel (carbon steel and stainless steel) and aluminum.
For calculation of greenhouse gases, we have considered greenhouse gas emissions generated by raw material extraction, material production, and waste management. The total amount of greenhouse gas emissions was calculated into tonnes of carbon dioxide equivalents (CO2e). The value per material was converted to the composition of each material partition so that each material partition received a discharge value in kilograms of CO2e per material partition. This was subsequently multiplied by the average weight per advertisement, in order to produce the tonnes of CO2e per ad. This emission value represents a standard for saved emissions from a product in the category that didn’t have to be produced. This value formed the basis for the calculation of the saved emissions for each product category of each site.
Transport and operation
For the calculation of emissions, we have also considered the impact of the transportation of goods between seller and buyer (not as an environmental benefit but as a negative impact). The estimation of distance gathered in Blocket’s customer survey is used for most of our sites because all other marketplaces respective distances are equivalent or lower. Our impact (not climate benefit) from the operations of data centers and offices was also added to the calculation. This was compiled by adding the climate impact from electricity production, both green electricity (wind and water) and the average national electricity mix (nuclear, hydro, coal condensate power, biofuel, etc.).
Carbon footprint calculator
All the data, ad data and the impact of operations was entered into the environmental footprint calculator that IVL has developed and the potential environmental benefits and savings of the categories were calculated.