The industry needs tools that allow the combined study of resource efficiency and GHG emission levels. In the primary aluminium industry, resource efficiency has traditionally focused on improving energy efficiency of single processes, often without considering material efficiency. In Europe, direct GHG emission levels from the primary aluminium industry are accounted for according to the methodologies introduced by the European Union Emission Trading Scheme (EU ETS). The overall GHG emissions from the industry sector in Europe are compelled to decrease each year by 1.74% between 2013 and 2020, and by 2.2% from 2021 onwards. In this study, a multi-layer Material Flow Analysis (MFA) was performed on Norsk Hydro's primary aluminium smelter in Sunndal, Norway, in order to connect resource efficiency analysis and GHG emissions accounting in a consistent way. The MFA was found to provide reliable results with a great level of detail. While the EU ETS accounting methodology fails to inform strategy makers and operators in the industry, MFA allowed to study the sensitivities of different flows to selected parameters, and to identify synergies to both improve resource efficiency and decrease GHG emission levels to conform with emission reduction targets. The greatest theoretical potentials to reduce direct GHG emissions in Hydro's primary aluminium smelter in Sunndal were found to lie in improving the alumina reduction reactions that occur during smelting (-7.1%), limiting air burn (-5.5%), changing energy carrier (-4.18%), reducing anode effect (-2.77%) and reducing the carbon losses in the anode plant (-0.02%). Moreover, potentials to reduce indirect GHG emissions and improve material efficiency beyond the boundaries of the plant are studied.