7 terms:

Heat pumps

Working like a Ôfridge in reverseÕ, heat pumps use compression and expansion of gases or liquid to draw heat from the natural energy stored in the ground or air. Both air source and ground source heat pumps can provide heating for buildings.

Heating degree day

The number of degrees that a day's average temperature is below a baseline temperature (typically either 15.5¡C or 18.3¡C) , below which buildings need to be heated.

Heavy Goods Vehicle (HGV)

A truck over 3.5 tonnes (articulated or rigid).

Home Insulation Scheme

The Scottish Government's area based residential energy efficiency scheme.

Hybrid vehicle

A vehicle powered by an internal combustion engine and electric motor that can provide power to the drive train individually or together.


A chemical compound comprised of hydrogen and carbon atoms, often used for fuel. Examples include methane, crude oil and oil products (e.g. petroleum, diesel and kerosene). Hydrocarbons release CO2 upon combustion.

Hydrogen fuel cell vehicle

Vehicle powered by an electric motor, with energy supplied by a hydrogen fuel cell.