Most Energy Efficient Heaters

energy efficient
(Energy efficiency) ways and technology that can reduce the amount of electricity or fuel used to do the same work. Such as keeping a house warm using less energy.
(Energy efficiency (physics)) Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The useful output may be electric power, mechanical work, or heat.
(Energy efficiency) One way of reducing greenhouse gas emissions. By cutting down on the energy our society needs to grow and develop, we can reduce the amount of greenhouse gas emissions.

heaters
A person or thing that heats, in particular a device for warming the air or water
A fastball
(heater) fastball: (baseball) a pitch thrown with maximum velocity; "he swung late on the fastball"; "he showed batters nothing but smoke"
A conductor used for indirect heating of the cathode of a thermionic tube
(heater) device that heats water or supplies warmth to a room
A heater is object that emits heat or causes another body to achieve a higher temperature. In a household or domestic setting, heaters are usually appliances whose purpose is to generate heating (i.e. warmth). Heaters exists for all states of matter, including solids, liquids and gases.