The following definitions reflect those used by the International Energy Agency (IEA); definitions used by other organisations and publications may vary.
hazardous air pollutants
Human Development Index
high voltage direct current
hydrogen fuel cell vehicle
heavy fuel oil
Human Poverty Index
Health & Safety Executive (United Kingdom)
heating seasonal performance factor
high temperature superconductor
heating, ventilation and air conditioning
high-voltage direct current line
coal of gross calorific value greater than 5 700 kilocalories per kilogramme on an ashfree but moist basis. Hard coal can be further disaggregated into anthracite, coking coal and other bituminous coal.
In IEA energy statistics, heat refers to heat produced for sale only. Most heat included in this category comes from the combustion of fuels, although some small amounts are produced from geothermal sources, electrically powered heat pumps and boilers.
Heat is obtained from fuels combustion, nuclear reactors, geothermal reservoirs, capture of sunlight, exothermic chemical processes and heat pumps which can extract it from ambient air and liquids. It may be used for heating or cooling or converted into mechanical energy for transport vehicles or electricity generation. Commercial heat sold is reported under total final consumption with the fuel inputs allocated under power generation.
heavy petroleum products include heavy fuel oil.
an investment fund opened to a limited range of investors. These funds aggressively manage a portfolio of investments that use advanced investment strategies such as leveraged, long, short and derivative positions with the goal of generating high returns.
measures life expectancy at birth, adult literacy and & school enrolment, and per-capita GDP (adjusted for purchasing power parity [PPP]). HPI-1 is a modified HPI for developing countries that measures probability at birth of not surviving to 40, adult literacy, % of population without clean water and % of children underweight.
the energy content of the electricity produced in hydropower plants assuming 100% efficiency.
the electrical energy derived from turbines being spun by fresh flowing water. This can be from rivers or from man-made installations, where water flows from a high-level reservoir down through a tunnel and away from a dam.
hectare (10 000 m2)