Backlit heated ceiling project in Revigny

Two functions in the same plenum

Backlighting a fabric calls for a distributed light source and enough distance to avoid visible hot spots. Heating calls for a regular air gap and a closed insulation layer. Both occupy the same volume, and it is that cohabitation which makes the job difficult.

The order of priority

Light decides. Badly distributed backlighting shows immediately, whereas a heating defect does not. The lighting lines are therefore set out first, and the heating system is organised around them.

The heat from the LEDs

An LED source still dissipates heat, which ends up in the closed plenum. That contribution is not a nuisance, it is even recovered by the system, but it has to be taken into account in the sizing rather than discovered at commissioning.

The fabric

Backlighting requires a translucent fabric, whose properties differ from an opaque one: diffusion, how it holds tension, sensitivity to cast shadows. That choice governs the spacing of the lighting lines and is settled with the supplier before ordering, because a translucent fabric cannot be swapped for another mid-job without reviewing the whole plenum.

Access for maintenance

LEDs have a long but finite life. Planning at design stage how they will be reached avoids a lighting failure, ten years later, forcing the removal of a heating ceiling in perfect working order. The usual answer is to keep a removable access around the perimeter, or to choose lighting lines joined by connectors rather than soldered, which costs almost nothing at fitting time.

Fitting the stretch ceiling is set out on part three of the series, and the system on the heated radiant stretch ceiling page.