There are two main types of heat used in poultry and livestock facilities - radiant (infrared heat) and convection (hot-air heat).
Radiant heat is like the sun's heat and is transferred by infrared heat waves. It is very efficient because it does not heat the building's air in order to heat the objects in the building. Instead, infrared waves heat the objects they are directed toward. In the case of a radiant heater, the heat waves emitting from the heater's glowing surface heat the birds and the litter. A small amount of convection heat is also produced.
With convection heat, the majority of the heater's BTU input is transferred to the air through convection. This means that most of the air in the building must be warmed to obtain the desired temperature at bird level. A space heater is an example of a 100 percent convection heater. The heater blows heated air into the house, and the birds and litter will not be warmed until the majority of the air volume in the house has been heated.