Redoing a ceiling? Have you come across the albedo effect?

Albedo, in two sentences

Albedo is the proportion of radiation a surface sends back rather than absorbs. A pale surface sends back, a dark surface absorbs and heats up. That is why a black roof reaches very high temperatures in summer, and why fresh snow stays cold in full sun.

What that changes at ceiling level

The ceiling is the largest pale surface in a room, and the only one that sees all the others. Its albedo decides how much light is sent back down, and therefore the lighting level obtained for the same electrical power. It also decides the infrared radiation that reaches you.

The moment the question arises

Redoing a ceiling is the one chance to act on that parameter with no extra site cost. The access equipment is up, the room is empty, the trades are there. Adding a reflective layer at that moment costs a fraction of what it would cost on its own.

What goes behind

Above the visible ceiling, insulation with aluminium faces sends the infrared back into the room instead of letting it escape into the loft. The visible face stays whatever you want it to be: paint, stretched fabric, timber panelling. The two functions are independent.

The effect on lighting

A ceiling that returns light better often allows the installed lighting power to be reduced, or a more even level to be obtained with the same number of fittings. It is a side effect, measurable, that few people anticipate.

The principle is developed on the page comparing an insulated ceiling to an igloo, and the insulation on the insulate your stretch ceilings page.