Energy intensity
Energy consumed per unit of economic output (e.g. MJ per USD of GDP) or per unit of activity, used as a proxy for energy efficiency.
Energy intensity most commonly means the ratio of total primary energy supply to gross domestic product, usually at purchasing power parity (PPP) in constant dollars. It is the headline indicator for UN Sustainable Development Goal target 7.3, which called for doubling the global rate of improvement in energy efficiency.
Annual improvement rate = 1 - (EI_t / EI_t-1)
Example: 620 EJ / about 180 trillion USD (2021 PPP) ≈ 3.4 MJ/USD
Global primary energy intensity fell by roughly 1.5–2% per year on average over 2010–2019 (IEA, IRENA, UN SDG 7 tracking), but slowed to around 1% in 2023. At COP28 in 2023, countries pledged to double the annual improvement rate to about 4% through 2030.
Intensity varies widely: countries with heavy industry, cold climates or energy-exporting economies (Russia, Canada, Saudi Arabia) have high intensity, while service-based economies (UK, Italy, Switzerland) are low. Changes in intensity reflect both genuine efficiency and structural shifts, such as moving manufacturing offshore, so analysts use decomposition (activity, structure, efficiency effects) and sector-level metrics: kWh per tonne of steel, MJ per passenger-km, kWh per m² of floor area. Statistical convention for primary energy also affects results; see final energy.
Related terms
All terms →- Primary energy
Energy in its raw natural form before conversion, such as crude oil, coal, natural gas, uranium, biomass, and the electricity or heat from renewables.
- Final energy
Energy delivered to end users (households, industry, transport, services) in forms such as electricity, fuels and district heat, after conversion and transmission.
- Tonne of oil equivalent (toe)
A conventional energy unit equal to 41.868 GJ (10 Gcal, 11.63 MWh), the nominal heat content of one tonne of crude oil, used in energy balances.
- Exajoule (EJ)
An SI unit of energy equal to 10¹⁸ joules (277.8 TWh), used to express national and global primary energy supply.
- EROI (Energy Return on Investment)
The ratio of usable energy delivered by an energy source over its lifetime to the energy invested to obtain and deliver it.