Energy Indicators for Sustainable Development: Guidelines and Methodologies International Atomic Energy Agency United Nations Department of Economic and Social Affairs International Energy Agency Eurostat European Environment Agency

(d) International Targets/Recommended Standards: Many industrialized countries 
have targets for reducing energy use and carbon emissions from transport. 
(e) Linkages to Other Indicators: This indicator is part of a set for energy intensities 
in different sectors (manufacturing, agriculture, service/commercial and residential), 
with energy use per unit of gross domestic product (GDP) as an aggregate energy 
intensity indicator. These indicators are also linked to indicators for total energy use, 
greenhouse gas emissions and air pollution emissions. 
METHODOLOGICAL DESCRIPTION 
(a) Underlying Definitions and Concepts: The transport indicators reflect how 
much energy is used to transport goods and people. The separation of freight transport 
and passenger travel is essential for energy analysis, both because they are largely 
based on different modes and because the activities driving energy use are different. 
The two activity measures (tonne-km and passenger-km) are quite distinct and are 
collected separately. However, separating the energy use in these two activities is 
often complicated given the way data are available from typical energy statistics. 
Changes in intensities are affected by factors other than energy efficiency; therefore, 
analysing intensity trends provides important insights into how energy efficiency and 
other factors affect energy use. Annex 3 includes a decomposition method for energy 
intensities. 
(b) Measuring Methods: 
Energy Use: Ideally, for road transport, energy use should be measured for each type 
of vehicle or means of transport, including two-wheel vehicles, automobiles, sport 
utility vehicles (SUVs) and buses for personal travel, and small trucks, heavy trucks 
and miscellaneous road vehicles for freight transport. Outside of road transport, both 
freight and personal travel should be divided into trains, ships and aircraft for 
domestic transport. In general, however, national energy balances are only 
disaggregated by fuel and broad traffic type or mode of transport: road, rail, water, air 
and pipeline. Thus, they give no information on energy use by individual means of 
road transport or, even more importantly, on the split between personal travel and 
freight transport. International air or maritime transport should not be included. 
Output or Activity: For assessing the efficiency of road vehicles, vehicle-km is a 
useful activity measure, assuming that data are available for each vehicle type. 
However, to be able to construct indicators across all modes for personal travel and 
freight transport, passenger-km and tonne-km, respectively, must be used as activity 

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variables. This also provides a better indication of how efficiently energy is used to 
provide personal mobility and distribution of goods. For example, from this 
perspective, a bus carrying 20 passengers for 10 km (200 passenger-km) is less energy 
intensive (more efficient) than the same bus carrying 5 passengers for the same 
distance (50 passenger-km). Similarly, a fully loaded truck is less energy intensive 
than the same truck carrying a partial load. 
Vehicle Intensities: Energy use per vehicle-km by vehicle and fuel type is an 
important indicator, as many standards for air pollution (and more recently, goals for 
CO
2
emissions reductions) are expressed in terms of vehicle characteristics, that is, 
emissions per vehicle-km. 
Modal Intensities: Energy use per passenger-km or tonne-km should be disaggregated 
by vehicle type, namely, two-wheel vehicle, automobile/van, bus, airplane, local and 
long-distance train, metro (also known as ‘subway’ or ‘underground’), tram, ship or 
ferry for passengers, and truck, train, ship or airplane for freight. 
Note: Aggregate energy intensities for travel or freight are a meaningful summary 
indicator whose value depends on both the mix of vehicles and the energy intensities 
of particular types of vehicles. The energy intensities of public train and bus transport 
per passenger-km are significantly lower than the energy intensities for automobiles 
or air transport. Freight, rail and ship transport are commonly less energy intensive 
than is trucking per tonne-km. It should also be noted that fuel consumption per 
vehicle-km also depends on traffic conditions as well as vehicle characteristics. 
The energy intensity of a vehicle depends on both capacity and capacity utilization. A 
large vehicle that is fully loaded generally has lower energy intensity per tonne-km 
than a fully loaded smaller vehicle, but a small vehicle fully loaded will have a lower 
energy intensity than a large vehicle with the same load. 
For some developed countries, typical load factors for private automobiles are 1.5 
persons per automobile. For rail and bus, load factors vary from well below 10% (e.g. 
United States city buses on average) to over 100% of nominal capacity at peak times 
(in many developing countries during most of the day). Typical load factors for 
trucking might be 60–80% of weight capacity when loaded, but trucks commonly run 
20–45% of their kilometres empty, yielding a relatively low overall load factor. 
Underutilized transport capacity means more pollution and road damage per unit of 
transport service delivered; hence capacity utilization itself is an important indicator 
of sustainable transport.