Which is the best source of heat?

A hot spot whose surface exceeds 80 °C, or even 100 °C, warms whatever is close to it but cannot spread an even warmth through a room.

The air near it gets so hot that it rises, and the people in the room never benefit from it.

Sunlight lights our days and passes its energy on to us.

Heat arriving from above suits us.

In a house, heating a volume of air takes a great deal of energy.

Sunlight warms our skin directly, without heating the air on the way. Long wave infrared heating reproduces that behaviour closely.

The sun's heat is at its most effective on a cloudless day when it is directly overhead.

Having nothing in the way is what makes heating both cheap to run and effective.

The sun spreads its warmth across everything below it.

The ceiling is the most available surface in a house. It is also the largest, which is what allows it to give a genuinely even warmth.

For lighting, the ceiling is the position usually chosen to get the most out of a light source.

The same holds for infrared light emitted from the ceiling.

The sun is the model for heating. A radiant ceiling is what comes closest to the way it works.