Like electric patio heating items, it distributes heat via radiation. This is the same form of heat given off by the sun. Radiant heat from the gas flame warms people and objects directly, without heating the air. This is the most efficient way of heating outdoors. In comparison, convection heaters that heat the air are very inefficient outdoors because the warm air is instantly lost as it disperses to cooler locations.
Some sites claim that gas heaters are less efficient than electric because they disperse heat in all directions, rather than direct it to where people are sitting. This may be true of very basic flame heating items which radiate heat from all possible angles. However, most modern types are fitted with a reflector above the gas flame which re-focuses the heat moving upwards and directs it down to the surrounding area. Some are even fitted with an adjustable reflector which allows you to point the heat in different directions – a great way to make sure none of the heat generated is wasted.