This paper is focusing on the influence of the loading factor on CO2 emissions, from freight and passengers. A
common approach in economics to relate greenhouse gas (GHG) emissions to economic activity is the ASIF model (Unander & Schipper 2000). However, this model has been
elaborated for all economic sectors, and it doesn’t take into account the vehicle load factor for the calculation of transport emissions. The objective of this paper is to include the loading factor into the ASIF approach. First, we will include this loading factor into the ASIF equation, aggregating step by step from trip level to macro level; loading will appear as a result of empty running, vehicle capacity and occupancy rate (section 2). Then section 3 will analyse the relationship between loading factor and energy consumption, per type of vehicle. Section 4 will focus on issues concerning freight, as well as section 5 for passengers. The examples will be mainly taken from road transport, which causes most of transport CO2 emissions. Then our conclusion will draw attention on data needs and policy implications.