eClim, a cooling stretch ceiling built on fourteen physical laws

Why one principle is not enough

A surface emitter brings several phenomena into play at once, and the result depends on their combination. Describing such a system by a single law amounts to describing a single facet of it, which explains most of the technical misunderstandings about it.

Radiation, the dominant phenomenon

Every surface exchanges radiation with the surfaces it can see, and the intensity of that exchange depends on the temperature difference between them. That mechanism produces most of the effect felt, in either direction.

Emissivity, which governs radiation

Two surfaces at the same temperature do not emit the same amount of radiation if their nature differs. That is why the choice of materials in the plenum counts as much as the output installed.

Conduction and the air gap

Heat also crosses materials by contact. A still air gap placed in the right position interrupts that path, and its presence or absence changes the behaviour of the whole more than any setting does.

Convection, which we try to reduce

A strong temperature difference between a surface and the air creates movement. A large, gently heated or gently cooled surface limits that difference, and therefore the movement, which is exactly the effect sought.

The dew point, in cooling mode

A cold surface condenses the water vapour in the air as soon as it drops below a certain temperature. That constraint does not exist in heating and becomes the main constraint as soon as the direction of operation is reversed.

The system is presented on the eClim page, and emissivity on the emissivity page.